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Merge pull request #18923 from ianic/add_flate

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add deflate implemented from first principles
This commit is contained in:
Andrew Kelley
2024-02-15 10:55:40 -08:00
committed by GitHub
parent 7204eccf5c 99cb201438
commit 57d6f789de
146 changed files with 5636 additions and 8733 deletions
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1
.gitattributes vendored
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@@ -4,6 +4,7 @@
langref.html.in text eol=lf
lib/std/compress/testdata/** binary
lib/std/compress/deflate/testdata/** binary
lib/std/compress/flate/testdata/** binary
lib/include/** linguist-vendored
lib/libc/** linguist-vendored

2
build.zig
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@@ -150,7 +150,7 @@ pub fn build(b: *std.Build) !void {
"rfc1951.txt",
"rfc1952.txt",
"rfc8478.txt",
// exclude files from lib/std/compress/deflate/testdata
// exclude files from lib/std/compress/flate/testdata
".expect",
".expect-noinput",
".golden",

10
lib/std/compress.zig
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@@ -1,11 +1,11 @@
const std = @import("std.zig");
pub const deflate = @import("compress/deflate.zig");
pub const flate = @import("compress/flate.zig");
pub const gzip = @import("compress/gzip.zig");
pub const zlib = @import("compress/zlib.zig");
pub const lzma = @import("compress/lzma.zig");
pub const lzma2 = @import("compress/lzma2.zig");
pub const xz = @import("compress/xz.zig");
pub const zlib = @import("compress/zlib.zig");
pub const zstd = @import("compress/zstandard.zig");
pub fn HashedReader(
@@ -69,11 +69,11 @@ pub fn hashedWriter(
}
test {
_ = deflate;
_ = gzip;
_ = lzma;
_ = lzma2;
_ = xz;
_ = zlib;
_ = zstd;
_ = flate;
_ = gzip;
_ = zlib;
}

44
lib/std/compress/deflate.zig
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@@ -1,44 +0,0 @@
//! The deflate package is a translation of the Go code of the compress/flate package from
//! https://go.googlesource.com/go/+/refs/tags/go1.17/src/compress/flate/
const deflate = @import("deflate/compressor.zig");
const inflate = @import("deflate/decompressor.zig");
pub const Compression = deflate.Compression;
pub const CompressorOptions = deflate.CompressorOptions;
pub const Compressor = deflate.Compressor;
pub const Decompressor = inflate.Decompressor;
pub const compressor = deflate.compressor;
pub const decompressor = inflate.decompressor;
/// Copies elements from a source `src` slice into a destination `dst` slice.
/// The copy never returns an error but might not be complete if the destination is too small.
/// Returns the number of elements copied, which will be the minimum of `src.len` and `dst.len`.
/// TODO: remove this smelly function
pub fn copy(dst: []u8, src: []const u8) usize {
if (dst.len <= src.len) {
@memcpy(dst, src[0..dst.len]);
return dst.len;
} else {
@memcpy(dst[0..src.len], src);
return src.len;
}
}
test {
_ = @import("deflate/token.zig");
_ = @import("deflate/bits_utils.zig");
_ = @import("deflate/dict_decoder.zig");
_ = @import("deflate/huffman_code.zig");
_ = @import("deflate/huffman_bit_writer.zig");
_ = @import("deflate/compressor.zig");
_ = @import("deflate/compressor_test.zig");
_ = @import("deflate/deflate_fast.zig");
_ = @import("deflate/deflate_fast_test.zig");
_ = @import("deflate/decompressor.zig");
}

33
lib/std/compress/deflate/bits_utils.zig
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@@ -1,33 +0,0 @@
const math = @import("std").math;
// Reverse bit-by-bit a N-bit code.
pub fn bitReverse(comptime T: type, value: T, N: usize) T {
const r = @bitReverse(value);
return r >> @as(math.Log2Int(T), @intCast(@typeInfo(T).Int.bits - N));
}
test "bitReverse" {
const std = @import("std");
const ReverseBitsTest = struct {
in: u16,
bit_count: u5,
out: u16,
};
const reverse_bits_tests = [_]ReverseBitsTest{
.{ .in = 1, .bit_count = 1, .out = 1 },
.{ .in = 1, .bit_count = 2, .out = 2 },
.{ .in = 1, .bit_count = 3, .out = 4 },
.{ .in = 1, .bit_count = 4, .out = 8 },
.{ .in = 1, .bit_count = 5, .out = 16 },
.{ .in = 17, .bit_count = 5, .out = 17 },
.{ .in = 257, .bit_count = 9, .out = 257 },
.{ .in = 29, .bit_count = 5, .out = 23 },
};
for (reverse_bits_tests) |h| {
const v = bitReverse(u16, h.in, h.bit_count);
try std.testing.expectEqual(h.out, v);
}
}

1110
lib/std/compress/deflate/compressor.zig
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531
lib/std/compress/deflate/compressor_test.zig
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@@ -1,531 +0,0 @@
const std = @import("std");
const expect = std.testing.expect;
const fifo = std.fifo;
const io = std.io;
const math = std.math;
const mem = std.mem;
const testing = std.testing;
const ArrayList = std.ArrayList;
const deflate = @import("compressor.zig");
const inflate = @import("decompressor.zig");
const compressor = deflate.compressor;
const decompressor = inflate.decompressor;
const huffman_only = deflate.huffman_only;
fn testSync(level: deflate.Compression, input: []const u8) !void {
if (input.len == 0) {
return;
}
var divided_buf = fifo
.LinearFifo(u8, fifo.LinearFifoBufferType.Dynamic)
.init(testing.allocator);
defer divided_buf.deinit();
var whole_buf = std.ArrayList(u8).init(testing.allocator);
defer whole_buf.deinit();
const multi_writer = io.multiWriter(.{
divided_buf.writer(),
whole_buf.writer(),
}).writer();
var comp = try compressor(
testing.allocator,
multi_writer,
.{ .level = level },
);
defer comp.deinit();
{
var decomp = try decompressor(
testing.allocator,
divided_buf.reader(),
null,
);
defer decomp.deinit();
// Write first half of the input and flush()
const half: usize = (input.len + 1) / 2;
var half_len: usize = half - 0;
{
_ = try comp.writer().writeAll(input[0..half]);
// Flush
try comp.flush();
// Read back
const decompressed = try testing.allocator.alloc(u8, half_len);
defer testing.allocator.free(decompressed);
const read = try decomp.reader().readAll(decompressed); // read at least half
try testing.expectEqual(half_len, read);
try testing.expectEqualSlices(u8, input[0..half], decompressed);
}
// Write last half of the input and close()
half_len = input.len - half;
{
_ = try comp.writer().writeAll(input[half..]);
// Close
try comp.close();
// Read back
const decompressed = try testing.allocator.alloc(u8, half_len);
defer testing.allocator.free(decompressed);
var read = try decomp.reader().readAll(decompressed);
try testing.expectEqual(half_len, read);
try testing.expectEqualSlices(u8, input[half..], decompressed);
// Extra read
var final: [10]u8 = undefined;
read = try decomp.reader().readAll(&final);
try testing.expectEqual(@as(usize, 0), read); // expect ended stream to return 0 bytes
try decomp.close();
}
}
_ = try comp.writer().writeAll(input);
try comp.close();
// stream should work for ordinary reader too (reading whole_buf in one go)
const whole_buf_reader = io.fixedBufferStream(whole_buf.items).reader();
var decomp = try decompressor(testing.allocator, whole_buf_reader, null);
defer decomp.deinit();
const decompressed = try testing.allocator.alloc(u8, input.len);
defer testing.allocator.free(decompressed);
_ = try decomp.reader().readAll(decompressed);
try decomp.close();
try testing.expectEqualSlices(u8, input, decompressed);
}
fn testToFromWithLevelAndLimit(level: deflate.Compression, input: []const u8, limit: u32) !void {
var compressed = std.ArrayList(u8).init(testing.allocator);
defer compressed.deinit();
var comp = try compressor(testing.allocator, compressed.writer(), .{ .level = level });
defer comp.deinit();
try comp.writer().writeAll(input);
try comp.close();
if (limit > 0) {
try expect(compressed.items.len <= limit);
}
var fib = io.fixedBufferStream(compressed.items);
var decomp = try decompressor(testing.allocator, fib.reader(), null);
defer decomp.deinit();
const decompressed = try testing.allocator.alloc(u8, input.len);
defer testing.allocator.free(decompressed);
const read: usize = try decomp.reader().readAll(decompressed);
try testing.expectEqual(input.len, read);
try testing.expectEqualSlices(u8, input, decompressed);
if (false) {
// TODO: this test has regressed
try testSync(level, input);
}
}
fn testToFromWithLimit(input: []const u8, limit: [11]u32) !void {
try testToFromWithLevelAndLimit(.no_compression, input, limit[0]);
try testToFromWithLevelAndLimit(.best_speed, input, limit[1]);
try testToFromWithLevelAndLimit(.level_2, input, limit[2]);
try testToFromWithLevelAndLimit(.level_3, input, limit[3]);
try testToFromWithLevelAndLimit(.level_4, input, limit[4]);
try testToFromWithLevelAndLimit(.level_5, input, limit[5]);
try testToFromWithLevelAndLimit(.level_6, input, limit[6]);
try testToFromWithLevelAndLimit(.level_7, input, limit[7]);
try testToFromWithLevelAndLimit(.level_8, input, limit[8]);
try testToFromWithLevelAndLimit(.best_compression, input, limit[9]);
try testToFromWithLevelAndLimit(.huffman_only, input, limit[10]);
}
test "deflate/inflate" {
const limits = [_]u32{0} ** 11;
var test0 = [_]u8{};
var test1 = [_]u8{0x11};
var test2 = [_]u8{ 0x11, 0x12 };
var test3 = [_]u8{ 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11 };
var test4 = [_]u8{ 0x11, 0x10, 0x13, 0x41, 0x21, 0x21, 0x41, 0x13, 0x87, 0x78, 0x13 };
try testToFromWithLimit(&test0, limits);
try testToFromWithLimit(&test1, limits);
try testToFromWithLimit(&test2, limits);
try testToFromWithLimit(&test3, limits);
try testToFromWithLimit(&test4, limits);
var large_data_chunk = try testing.allocator.alloc(u8, 100_000);
defer testing.allocator.free(large_data_chunk);
// fill with random data
for (large_data_chunk, 0..) |_, i| {
large_data_chunk[i] = @as(u8, @truncate(i)) *% @as(u8, @truncate(i));
}
try testToFromWithLimit(large_data_chunk, limits);
}
test "very long sparse chunk" {
// A SparseReader returns a stream consisting of 0s ending with 65,536 (1<<16) 1s.
// This tests missing hash references in a very large input.
const SparseReader = struct {
l: usize, // length
cur: usize, // current position
const Self = @This();
const Error = error{};
pub const Reader = io.Reader(*Self, Error, read);
pub fn reader(self: *Self) Reader {
return .{ .context = self };
}
fn read(s: *Self, b: []u8) Error!usize {
var n: usize = 0; // amount read
if (s.cur >= s.l) {
return 0;
}
n = b.len;
var cur = s.cur + n;
if (cur > s.l) {
n -= cur - s.l;
cur = s.l;
}
for (b[0..n], 0..) |_, i| {
if (s.cur + i >= s.l -| (1 << 16)) {
b[i] = 1;
} else {
b[i] = 0;
}
}
s.cur = cur;
return n;
}
};
var comp = try compressor(
testing.allocator,
io.null_writer,
.{ .level = .best_speed },
);
defer comp.deinit();
var writer = comp.writer();
var sparse = SparseReader{ .l = 0x23e8, .cur = 0 };
var reader = sparse.reader();
var read: usize = 1;
var written: usize = 0;
while (read > 0) {
var buf: [1 << 15]u8 = undefined; // 32,768 bytes buffer
read = try reader.read(&buf);
written += try writer.write(buf[0..read]);
}
try testing.expectEqual(@as(usize, 0x23e8), written);
}
test "compressor reset" {
for (std.enums.values(deflate.Compression)) |c| {
try testWriterReset(c, null);
try testWriterReset(c, "dict");
try testWriterReset(c, "hello");
}
}
fn testWriterReset(level: deflate.Compression, dict: ?[]const u8) !void {
const filler = struct {
fn writeData(c: anytype) !void {
const msg = "all your base are belong to us";
try c.writer().writeAll(msg);
try c.flush();
const hello = "hello world";
var i: usize = 0;
while (i < 1024) : (i += 1) {
try c.writer().writeAll(hello);
}
i = 0;
while (i < 65000) : (i += 1) {
try c.writer().writeAll("x");
}
}
};
var buf1 = ArrayList(u8).init(testing.allocator);
defer buf1.deinit();
var buf2 = ArrayList(u8).init(testing.allocator);
defer buf2.deinit();
var comp = try compressor(
testing.allocator,
buf1.writer(),
.{ .level = level, .dictionary = dict },
);
defer comp.deinit();
try filler.writeData(&comp);
try comp.close();
comp.reset(buf2.writer());
try filler.writeData(&comp);
try comp.close();
try testing.expectEqualSlices(u8, buf1.items, buf2.items);
}
test "decompressor dictionary" {
const dict = "hello world"; // dictionary
const text = "hello again world";
var compressed = fifo
.LinearFifo(u8, fifo.LinearFifoBufferType.Dynamic)
.init(testing.allocator);
defer compressed.deinit();
var comp = try compressor(
testing.allocator,
compressed.writer(),
.{
.level = .level_5,
.dictionary = null, // no dictionary
},
);
defer comp.deinit();
// imitate a compressor with a dictionary
try comp.writer().writeAll(dict);
try comp.flush();
compressed.discard(compressed.readableLength()); // empty the output
try comp.writer().writeAll(text);
try comp.close();
const decompressed = try testing.allocator.alloc(u8, text.len);
defer testing.allocator.free(decompressed);
var decomp = try decompressor(
testing.allocator,
compressed.reader(),
dict,
);
defer decomp.deinit();
_ = try decomp.reader().readAll(decompressed);
try testing.expectEqualSlices(u8, "hello again world", decompressed);
}
test "compressor dictionary" {
const dict = "hello world";
const text = "hello again world";
var compressed_nd = fifo
.LinearFifo(u8, fifo.LinearFifoBufferType.Dynamic)
.init(testing.allocator); // compressed with no dictionary
defer compressed_nd.deinit();
var compressed_d = ArrayList(u8).init(testing.allocator); // compressed with a dictionary
defer compressed_d.deinit();
// imitate a compressor with a dictionary
var comp_nd = try compressor(
testing.allocator,
compressed_nd.writer(),
.{
.level = .level_5,
.dictionary = null, // no dictionary
},
);
defer comp_nd.deinit();
try comp_nd.writer().writeAll(dict);
try comp_nd.flush();
compressed_nd.discard(compressed_nd.readableLength()); // empty the output
try comp_nd.writer().writeAll(text);
try comp_nd.close();
// use a compressor with a dictionary
var comp_d = try compressor(
testing.allocator,
compressed_d.writer(),
.{
.level = .level_5,
.dictionary = dict, // with a dictionary
},
);
defer comp_d.deinit();
try comp_d.writer().writeAll(text);
try comp_d.close();
try testing.expectEqualSlices(u8, compressed_d.items, compressed_nd.readableSlice(0));
}
// Update the hash for best_speed only if d.index < d.maxInsertIndex
// See https://golang.org/issue/2508
test "Go non-regression test for 2508" {
var comp = try compressor(
testing.allocator,
io.null_writer,
.{ .level = .best_speed },
);
defer comp.deinit();
var buf = [_]u8{0} ** 1024;
var i: usize = 0;
while (i < 131_072) : (i += 1) {
try comp.writer().writeAll(&buf);
try comp.close();
}
}
test "deflate/inflate string" {
const StringTest = struct {
filename: []const u8,
limit: [11]u32,
};
const deflate_inflate_string_tests = [_]StringTest{
.{
.filename = "compress-e.txt",
.limit = [11]u32{
100_018, // no_compression
50_650, // best_speed
50_960, // 2
51_150, // 3
50_930, // 4
50_790, // 5
50_790, // 6
50_790, // 7
50_790, // 8
50_790, // best_compression
43_683, // huffman_only
},
},
.{
.filename = "rfc1951.txt",
.limit = [11]u32{
36_954, // no_compression
12_952, // best_speed
12_228, // 2
12_016, // 3
11_466, // 4
11_191, // 5
11_129, // 6
11_120, // 7
11_112, // 8
11_109, // best_compression
20_273, // huffman_only
},
},
};
inline for (deflate_inflate_string_tests) |t| {
const golden = @embedFile("testdata/" ++ t.filename);
try testToFromWithLimit(golden, t.limit);
}
}
test "inflate reset" {
const strings = [_][]const u8{
"lorem ipsum izzle fo rizzle",
"the quick brown fox jumped over",
};
var compressed_strings = [_]ArrayList(u8){
ArrayList(u8).init(testing.allocator),
ArrayList(u8).init(testing.allocator),
};
defer compressed_strings[0].deinit();
defer compressed_strings[1].deinit();
for (strings, 0..) |s, i| {
var comp = try compressor(
testing.allocator,
compressed_strings[i].writer(),
.{ .level = .level_6 },
);
defer comp.deinit();
try comp.writer().writeAll(s);
try comp.close();
}
var fib = io.fixedBufferStream(compressed_strings[0].items);
var decomp = try decompressor(testing.allocator, fib.reader(), null);
defer decomp.deinit();
const decompressed_0: []u8 = try decomp.reader()
.readAllAlloc(testing.allocator, math.maxInt(usize));
defer testing.allocator.free(decompressed_0);
fib = io.fixedBufferStream(compressed_strings[1].items);
try decomp.reset(fib.reader(), null);
const decompressed_1: []u8 = try decomp.reader()
.readAllAlloc(testing.allocator, math.maxInt(usize));
defer testing.allocator.free(decompressed_1);
try decomp.close();
try testing.expectEqualSlices(u8, strings[0], decompressed_0);
try testing.expectEqualSlices(u8, strings[1], decompressed_1);
}
test "inflate reset dictionary" {
const dict = "the lorem fox";
const strings = [_][]const u8{
"lorem ipsum izzle fo rizzle",
"the quick brown fox jumped over",
};
var compressed_strings = [_]ArrayList(u8){
ArrayList(u8).init(testing.allocator),
ArrayList(u8).init(testing.allocator),
};
defer compressed_strings[0].deinit();
defer compressed_strings[1].deinit();
for (strings, 0..) |s, i| {
var comp = try compressor(
testing.allocator,
compressed_strings[i].writer(),
.{ .level = .level_6 },
);
defer comp.deinit();
try comp.writer().writeAll(s);
try comp.close();
}
var fib = io.fixedBufferStream(compressed_strings[0].items);
var decomp = try decompressor(testing.allocator, fib.reader(), dict);
defer decomp.deinit();
const decompressed_0: []u8 = try decomp.reader()
.readAllAlloc(testing.allocator, math.maxInt(usize));
defer testing.allocator.free(decompressed_0);
fib = io.fixedBufferStream(compressed_strings[1].items);
try decomp.reset(fib.reader(), dict);
const decompressed_1: []u8 = try decomp.reader()
.readAllAlloc(testing.allocator, math.maxInt(usize));
defer testing.allocator.free(decompressed_1);
try decomp.close();
try testing.expectEqualSlices(u8, strings[0], decompressed_0);
try testing.expectEqualSlices(u8, strings[1], decompressed_1);
}

1119
lib/std/compress/deflate/decompressor.zig
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28
lib/std/compress/deflate/deflate_const.zig
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@@ -1,28 +0,0 @@
// Deflate
// Biggest block size for uncompressed block.
pub const max_store_block_size = 65535;
// The special code used to mark the end of a block.
pub const end_block_marker = 256;
// LZ77
// The smallest match length per the RFC section 3.2.5
pub const base_match_length = 3;
// The smallest match offset.
pub const base_match_offset = 1;
// The largest match length.
pub const max_match_length = 258;
// The largest match offset.
pub const max_match_offset = 1 << 15;
// Huffman Codes
// The largest offset code.
pub const offset_code_count = 30;
// Max number of frequencies used for a Huffman Code
// Possible lengths are codegenCodeCount (19), offset_code_count (30) and max_num_lit (286).
// The largest of these is max_num_lit.
pub const max_num_frequencies = max_num_lit;
// Maximum number of literals.
pub const max_num_lit = 286;

728
lib/std/compress/deflate/deflate_fast.zig
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@@ -1,728 +0,0 @@
// This encoding algorithm, which prioritizes speed over output size, is
// based on Snappy's LZ77-style encoder: github.com/golang/snappy
const std = @import("std");
const math = std.math;
const mem = std.mem;
const Allocator = std.mem.Allocator;
const deflate_const = @import("deflate_const.zig");
const deflate = @import("compressor.zig");
const token = @import("token.zig");
const base_match_length = deflate_const.base_match_length;
const base_match_offset = deflate_const.base_match_offset;
const max_match_length = deflate_const.max_match_length;
const max_match_offset = deflate_const.max_match_offset;
const max_store_block_size = deflate_const.max_store_block_size;
const table_bits = 14; // Bits used in the table.
const table_mask = table_size - 1; // Mask for table indices. Redundant, but can eliminate bounds checks.
const table_shift = 32 - table_bits; // Right-shift to get the table_bits most significant bits of a uint32.
const table_size = 1 << table_bits; // Size of the table.
// Reset the buffer offset when reaching this.
// Offsets are stored between blocks as i32 values.
// Since the offset we are checking against is at the beginning
// of the buffer, we need to subtract the current and input
// buffer to not risk overflowing the i32.
const buffer_reset = math.maxInt(i32) - max_store_block_size * 2;
fn load32(b: []u8, i: i32) u32 {
const s = b[@as(usize, @intCast(i)) .. @as(usize, @intCast(i)) + 4];
return @as(u32, @intCast(s[0])) |
@as(u32, @intCast(s[1])) << 8 |
@as(u32, @intCast(s[2])) << 16 |
@as(u32, @intCast(s[3])) << 24;
}
fn load64(b: []u8, i: i32) u64 {
const s = b[@as(usize, @intCast(i))..@as(usize, @intCast(i + 8))];
return @as(u64, @intCast(s[0])) |
@as(u64, @intCast(s[1])) << 8 |
@as(u64, @intCast(s[2])) << 16 |
@as(u64, @intCast(s[3])) << 24 |
@as(u64, @intCast(s[4])) << 32 |
@as(u64, @intCast(s[5])) << 40 |
@as(u64, @intCast(s[6])) << 48 |
@as(u64, @intCast(s[7])) << 56;
}
fn hash(u: u32) u32 {
return (u *% 0x1e35a7bd) >> table_shift;
}
// These constants are defined by the Snappy implementation so that its
// assembly implementation can fast-path some 16-bytes-at-a-time copies.
// They aren't necessary in the pure Go implementation, and may not be
// necessary in Zig, but using the same thresholds doesn't really hurt.
const input_margin = 16 - 1;
const min_non_literal_block_size = 1 + 1 + input_margin;
const TableEntry = struct {
val: u32, // Value at destination
offset: i32,
};
pub fn deflateFast() DeflateFast {
return DeflateFast{
.table = [_]TableEntry{.{ .val = 0, .offset = 0 }} ** table_size,
.prev = undefined,
.prev_len = 0,
.cur = max_store_block_size,
.allocator = undefined,
};
}
// DeflateFast maintains the table for matches,
// and the previous byte block for cross block matching.
pub const DeflateFast = struct {
table: [table_size]TableEntry,
prev: []u8, // Previous block, zero length if unknown.
prev_len: u32, // Previous block length
cur: i32, // Current match offset.
allocator: Allocator,
const Self = @This();
pub fn init(self: *Self, allocator: Allocator) !void {
self.allocator = allocator;
self.prev = try allocator.alloc(u8, max_store_block_size);
self.prev_len = 0;
}
pub fn deinit(self: *Self) void {
self.allocator.free(self.prev);
self.prev_len = 0;
}
// Encodes a block given in `src` and appends tokens to `dst` and returns the result.
pub fn encode(self: *Self, dst: []token.Token, tokens_count: *u16, src: []u8) void {
// Ensure that self.cur doesn't wrap.
if (self.cur >= buffer_reset) {
self.shiftOffsets();
}
// This check isn't in the Snappy implementation, but there, the caller
// instead of the callee handles this case.
if (src.len < min_non_literal_block_size) {
self.cur += max_store_block_size;
self.prev_len = 0;
emitLiteral(dst, tokens_count, src);
return;
}
// s_limit is when to stop looking for offset/length copies. The input_margin
// lets us use a fast path for emitLiteral in the main loop, while we are
// looking for copies.
const s_limit = @as(i32, @intCast(src.len - input_margin));
// next_emit is where in src the next emitLiteral should start from.
var next_emit: i32 = 0;
var s: i32 = 0;
var cv: u32 = load32(src, s);
var next_hash: u32 = hash(cv);
outer: while (true) {
// Copied from the C++ snappy implementation:
//
// Heuristic match skipping: If 32 bytes are scanned with no matches
// found, start looking only at every other byte. If 32 more bytes are
// scanned (or skipped), look at every third byte, etc.. When a match
// is found, immediately go back to looking at every byte. This is a
// small loss (~5% performance, ~0.1% density) for compressible data
// due to more bookkeeping, but for non-compressible data (such as
// JPEG) it's a huge win since the compressor quickly "realizes" the
// data is incompressible and doesn't bother looking for matches
// everywhere.
//
// The "skip" variable keeps track of how many bytes there are since
// the last match; dividing it by 32 (ie. right-shifting by five) gives
// the number of bytes to move ahead for each iteration.
var skip: i32 = 32;
var next_s: i32 = s;
var candidate: TableEntry = undefined;
while (true) {
s = next_s;
const bytes_between_hash_lookups = skip >> 5;
next_s = s + bytes_between_hash_lookups;
skip += bytes_between_hash_lookups;
if (next_s > s_limit) {
break :outer;
}
candidate = self.table[next_hash & table_mask];
const now = load32(src, next_s);
self.table[next_hash & table_mask] = .{ .offset = s + self.cur, .val = cv };
next_hash = hash(now);
const offset = s - (candidate.offset - self.cur);
if (offset > max_match_offset or cv != candidate.val) {
// Out of range or not matched.
cv = now;
continue;
}
break;
}
// A 4-byte match has been found. We'll later see if more than 4 bytes
// match. But, prior to the match, src[next_emit..s] are unmatched. Emit
// them as literal bytes.
emitLiteral(dst, tokens_count, src[@as(usize, @intCast(next_emit))..@as(usize, @intCast(s))]);
// Call emitCopy, and then see if another emitCopy could be our next
// move. Repeat until we find no match for the input immediately after
// what was consumed by the last emitCopy call.
//
// If we exit this loop normally then we need to call emitLiteral next,
// though we don't yet know how big the literal will be. We handle that
// by proceeding to the next iteration of the main loop. We also can
// exit this loop via goto if we get close to exhausting the input.
while (true) {
// Invariant: we have a 4-byte match at s, and no need to emit any
// literal bytes prior to s.
// Extend the 4-byte match as long as possible.
//
s += 4;
const t = candidate.offset - self.cur + 4;
const l = self.matchLen(s, t, src);
// matchToken is flate's equivalent of Snappy's emitCopy. (length,offset)
dst[tokens_count.*] = token.matchToken(
@as(u32, @intCast(l + 4 - base_match_length)),
@as(u32, @intCast(s - t - base_match_offset)),
);
tokens_count.* += 1;
s += l;
next_emit = s;
if (s >= s_limit) {
break :outer;
}
// We could immediately start working at s now, but to improve
// compression we first update the hash table at s-1 and at s. If
// another emitCopy is not our next move, also calculate next_hash
// at s+1. At least on amd64 architecture, these three hash calculations
// are faster as one load64 call (with some shifts) instead of
// three load32 calls.
var x = load64(src, s - 1);
const prev_hash = hash(@as(u32, @truncate(x)));
self.table[prev_hash & table_mask] = TableEntry{
.offset = self.cur + s - 1,
.val = @as(u32, @truncate(x)),
};
x >>= 8;
const curr_hash = hash(@as(u32, @truncate(x)));
candidate = self.table[curr_hash & table_mask];
self.table[curr_hash & table_mask] = TableEntry{
.offset = self.cur + s,
.val = @as(u32, @truncate(x)),
};
const offset = s - (candidate.offset - self.cur);
if (offset > max_match_offset or @as(u32, @truncate(x)) != candidate.val) {
cv = @as(u32, @truncate(x >> 8));
next_hash = hash(cv);
s += 1;
break;
}
}
}
if (@as(u32, @intCast(next_emit)) < src.len) {
emitLiteral(dst, tokens_count, src[@as(usize, @intCast(next_emit))..]);
}
self.cur += @as(i32, @intCast(src.len));
self.prev_len = @as(u32, @intCast(src.len));
@memcpy(self.prev[0..self.prev_len], src);
return;
}
fn emitLiteral(dst: []token.Token, tokens_count: *u16, lit: []u8) void {
for (lit) |v| {
dst[tokens_count.*] = token.literalToken(@as(u32, @intCast(v)));
tokens_count.* += 1;
}
return;
}
// matchLen returns the match length between src[s..] and src[t..].
// t can be negative to indicate the match is starting in self.prev.
// We assume that src[s-4 .. s] and src[t-4 .. t] already match.
fn matchLen(self: *Self, s: i32, t: i32, src: []u8) i32 {
var s1 = @as(u32, @intCast(s)) + max_match_length - 4;
if (s1 > src.len) {
s1 = @as(u32, @intCast(src.len));
}
// If we are inside the current block
if (t >= 0) {
var b = src[@as(usize, @intCast(t))..];
const a = src[@as(usize, @intCast(s))..@as(usize, @intCast(s1))];
b = b[0..a.len];
// Extend the match to be as long as possible.
for (a, 0..) |_, i| {
if (a[i] != b[i]) {
return @as(i32, @intCast(i));
}
}
return @as(i32, @intCast(a.len));
}
// We found a match in the previous block.
const tp = @as(i32, @intCast(self.prev_len)) + t;
if (tp < 0) {
return 0;
}
// Extend the match to be as long as possible.
var a = src[@as(usize, @intCast(s))..@as(usize, @intCast(s1))];
var b = self.prev[@as(usize, @intCast(tp))..@as(usize, @intCast(self.prev_len))];
if (b.len > a.len) {
b = b[0..a.len];
}
a = a[0..b.len];
for (b, 0..) |_, i| {
if (a[i] != b[i]) {
return @as(i32, @intCast(i));
}
}
// If we reached our limit, we matched everything we are
// allowed to in the previous block and we return.
const n = @as(i32, @intCast(b.len));
if (@as(u32, @intCast(s + n)) == s1) {
return n;
}
// Continue looking for more matches in the current block.
a = src[@as(usize, @intCast(s + n))..@as(usize, @intCast(s1))];
b = src[0..a.len];
for (a, 0..) |_, i| {
if (a[i] != b[i]) {
return @as(i32, @intCast(i)) + n;
}
}
return @as(i32, @intCast(a.len)) + n;
}
// Reset resets the encoding history.
// This ensures that no matches are made to the previous block.
pub fn reset(self: *Self) void {
self.prev_len = 0;
// Bump the offset, so all matches will fail distance check.
// Nothing should be >= self.cur in the table.
self.cur += max_match_offset;
// Protect against self.cur wraparound.
if (self.cur >= buffer_reset) {
self.shiftOffsets();
}
}
// shiftOffsets will shift down all match offset.
// This is only called in rare situations to prevent integer overflow.
//
// See https://golang.org/issue/18636 and https://golang.org/issues/34121.
fn shiftOffsets(self: *Self) void {
if (self.prev_len == 0) {
// We have no history; just clear the table.
for (self.table, 0..) |_, i| {
self.table[i] = TableEntry{ .val = 0, .offset = 0 };
}
self.cur = max_match_offset + 1;
return;
}
// Shift down everything in the table that isn't already too far away.
for (self.table, 0..) |_, i| {
var v = self.table[i].offset - self.cur + max_match_offset + 1;
if (v < 0) {
// We want to reset self.cur to max_match_offset + 1, so we need to shift
// all table entries down by (self.cur - (max_match_offset + 1)).
// Because we ignore matches > max_match_offset, we can cap
// any negative offsets at 0.
v = 0;
}
self.table[i].offset = v;
}
self.cur = max_match_offset + 1;
}
};
test "best speed match 1/3" {
if (@import("builtin").os.tag == .wasi) {
// https://github.com/ziglang/zig/issues/18885
return error.SkipZigTest;
}
const expectEqual = std.testing.expectEqual;
{
var previous = [_]u8{ 0, 0, 0, 1, 2 };
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 3, 4, 5, 0, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(3, -3, &current);
try expectEqual(@as(i32, 6), got);
}
{
var previous = [_]u8{ 0, 0, 0, 1, 2 };
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 2, 4, 5, 0, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(3, -3, &current);
try expectEqual(@as(i32, 3), got);
}
{
var previous = [_]u8{ 0, 0, 0, 1, 1 };
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 3, 4, 5, 0, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(3, -3, &current);
try expectEqual(@as(i32, 2), got);
}
{
var previous = [_]u8{ 0, 0, 0, 1, 2 };
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 2, 2, 2, 2, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(0, -1, &current);
try expectEqual(@as(i32, 4), got);
}
{
var previous = [_]u8{ 0, 0, 0, 1, 2, 3, 4, 5, 2, 2 };
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 2, 2, 2, 2, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(4, -7, &current);
try expectEqual(@as(i32, 5), got);
}
{
var previous = [_]u8{ 9, 9, 9, 9, 9 };
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 2, 2, 2, 2, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(0, -1, &current);
try expectEqual(@as(i32, 0), got);
}
{
var previous = [_]u8{ 9, 9, 9, 9, 9 };
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 9, 2, 2, 2, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(1, 0, &current);
try expectEqual(@as(i32, 0), got);
}
}
test "best speed match 2/3" {
if (@import("builtin").os.tag == .wasi) {
// https://github.com/ziglang/zig/issues/18885
return error.SkipZigTest;
}
const expectEqual = std.testing.expectEqual;
{
var previous = [_]u8{};
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 9, 2, 2, 2, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(1, -5, &current);
try expectEqual(@as(i32, 0), got);
}
{
var previous = [_]u8{};
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 9, 2, 2, 2, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(1, -1, &current);
try expectEqual(@as(i32, 0), got);
}
{
var previous = [_]u8{};
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 2, 2, 2, 2, 1, 2, 3, 4, 5 };
const got: i32 = e.matchLen(1, 0, &current);
try expectEqual(@as(i32, 3), got);
}
{
var previous = [_]u8{ 3, 4, 5 };
var e = DeflateFast{
.prev = &previous,
.prev_len = previous.len,
.table = undefined,
.allocator = undefined,
.cur = 0,
};
var current = [_]u8{ 3, 4, 5 };
const got: i32 = e.matchLen(0, -3, &current);
try expectEqual(@as(i32, 3), got);
}
}
test "best speed match 2/2" {
const testing = std.testing;
const expectEqual = testing.expectEqual;
const Case = struct {
previous: u32,
current: u32,
s: i32,
t: i32,
expected: i32,
};
const cases = [_]Case{
.{
.previous = 1000,
.current = 1000,
.s = 0,
.t = -1000,
.expected = max_match_length - 4,
},
.{
.previous = 200,
.s = 0,
.t = -200,
.current = 500,
.expected = max_match_length - 4,
},
.{
.previous = 200,
.s = 1,
.t = 0,
.current = 500,
.expected = max_match_length - 4,
},
.{
.previous = max_match_length - 4,
.s = 0,
.t = -(max_match_length - 4),
.current = 500,
.expected = max_match_length - 4,
},
.{
.previous = 200,
.s = 400,
.t = -200,
.current = 500,
.expected = 100,
},
.{
.previous = 10,
.s = 400,
.t = 200,
.current = 500,
.expected = 100,
},
};
for (cases) |c| {
const previous = try testing.allocator.alloc(u8, c.previous);
defer testing.allocator.free(previous);
@memset(previous, 0);
const current = try testing.allocator.alloc(u8, c.current);
defer testing.allocator.free(current);
@memset(current, 0);
var e = DeflateFast{
.prev = previous,
.prev_len = @as(u32, @intCast(previous.len)),
.table = undefined,
.allocator = undefined,
.cur = 0,
};
const got: i32 = e.matchLen(c.s, c.t, current);
try expectEqual(@as(i32, c.expected), got);
}
}
test "best speed shift offsets" {
const testing = std.testing;
const expect = std.testing.expect;
// Test if shiftoffsets properly preserves matches and resets out-of-range matches
// seen in https://github.com/golang/go/issues/4142
var enc = deflateFast();
try enc.init(testing.allocator);
defer enc.deinit();
// test_data may not generate internal matches.
var test_data = [32]u8{
0xf5, 0x25, 0xf2, 0x55, 0xf6, 0xc1, 0x1f, 0x0b, 0x10, 0xa1,
0xd0, 0x77, 0x56, 0x38, 0xf1, 0x9c, 0x7f, 0x85, 0xc5, 0xbd,
0x16, 0x28, 0xd4, 0xf9, 0x03, 0xd4, 0xc0, 0xa1, 0x1e, 0x58,
0x5b, 0xc9,
};
var tokens = [_]token.Token{0} ** 32;
var tokens_count: u16 = 0;
// Encode the testdata with clean state.
// Second part should pick up matches from the first block.
tokens_count = 0;
enc.encode(&tokens, &tokens_count, &test_data);
const want_first_tokens = tokens_count;
tokens_count = 0;
enc.encode(&tokens, &tokens_count, &test_data);
const want_second_tokens = tokens_count;
try expect(want_first_tokens > want_second_tokens);
// Forward the current indicator to before wraparound.
enc.cur = buffer_reset - @as(i32, @intCast(test_data.len));
// Part 1 before wrap, should match clean state.
tokens_count = 0;
enc.encode(&tokens, &tokens_count, &test_data);
var got = tokens_count;
try testing.expectEqual(want_first_tokens, got);
// Verify we are about to wrap.
try testing.expectEqual(@as(i32, buffer_reset), enc.cur);
// Part 2 should match clean state as well even if wrapped.
tokens_count = 0;
enc.encode(&tokens, &tokens_count, &test_data);
got = tokens_count;
try testing.expectEqual(want_second_tokens, got);
// Verify that we wrapped.
try expect(enc.cur < buffer_reset);
// Forward the current buffer, leaving the matches at the bottom.
enc.cur = buffer_reset;
enc.shiftOffsets();
// Ensure that no matches were picked up.
tokens_count = 0;
enc.encode(&tokens, &tokens_count, &test_data);
got = tokens_count;
try testing.expectEqual(want_first_tokens, got);
}
test "best speed reset" {
// test that encoding is consistent across a warparound of the table offset.
// See https://github.com/golang/go/issues/34121
const fmt = std.fmt;
const testing = std.testing;
const ArrayList = std.ArrayList;
const input_size = 65536;
const input = try testing.allocator.alloc(u8, input_size);
defer testing.allocator.free(input);
var i: usize = 0;
while (i < input_size) : (i += 1) {
_ = try fmt.bufPrint(input, "asdfasdfasdfasdf{d}{d}fghfgujyut{d}yutyu\n", .{ i, i, i });
}
// This is specific to level 1 (best_speed).
const level = .best_speed;
const offset: usize = 1;
// We do an encode with a clean buffer to compare.
var want = ArrayList(u8).init(testing.allocator);
defer want.deinit();
var clean_comp = try deflate.compressor(
testing.allocator,
want.writer(),
.{ .level = level },
);
defer clean_comp.deinit();
// Write 3 times, close.
try clean_comp.writer().writeAll(input);
try clean_comp.writer().writeAll(input);
try clean_comp.writer().writeAll(input);
try clean_comp.close();
var o = offset;
while (o <= 256) : (o *= 2) {
var discard = ArrayList(u8).init(testing.allocator);
defer discard.deinit();
var comp = try deflate.compressor(
testing.allocator,
discard.writer(),
.{ .level = level },
);
defer comp.deinit();
// Reset until we are right before the wraparound.
// Each reset adds max_match_offset to the offset.
i = 0;
const limit = (buffer_reset - input.len - o - max_match_offset) / max_match_offset;
while (i < limit) : (i += 1) {
// skip ahead to where we are close to wrap around...
comp.reset(discard.writer());
}
var got = ArrayList(u8).init(testing.allocator);
defer got.deinit();
comp.reset(got.writer());
// Write 3 times, close.
try comp.writer().writeAll(input);
try comp.writer().writeAll(input);
try comp.writer().writeAll(input);
try comp.close();
// output must match at wraparound
try testing.expectEqualSlices(u8, want.items, got.items);
}
}

160
lib/std/compress/deflate/deflate_fast_test.zig
View File

@@ -1,160 +0,0 @@
const std = @import("std");
const expect = std.testing.expect;
const io = std.io;
const mem = std.mem;
const testing = std.testing;
const ArrayList = std.ArrayList;
const deflate = @import("compressor.zig");
const inflate = @import("decompressor.zig");
const deflate_const = @import("deflate_const.zig");
test "best speed" {
// Tests that round-tripping through deflate and then inflate recovers the original input.
// The Write sizes are near the thresholds in the compressor.encSpeed method (0, 16, 128), as well
// as near `deflate_const.max_store_block_size` (65535).
var abcabc = try testing.allocator.alloc(u8, 131_072);
defer testing.allocator.free(abcabc);
for (abcabc, 0..) |_, i| {
abcabc[i] = @as(u8, @intCast(i % 128));
}
var tc_01 = [_]u32{ 65536, 0 };
var tc_02 = [_]u32{ 65536, 1 };
var tc_03 = [_]u32{ 65536, 1, 256 };
var tc_04 = [_]u32{ 65536, 1, 65536 };
var tc_05 = [_]u32{ 65536, 14 };
var tc_06 = [_]u32{ 65536, 15 };
var tc_07 = [_]u32{ 65536, 16 };
var tc_08 = [_]u32{ 65536, 16, 256 };
var tc_09 = [_]u32{ 65536, 16, 65536 };
var tc_10 = [_]u32{ 65536, 127 };
var tc_11 = [_]u32{ 65536, 127 };
var tc_12 = [_]u32{ 65536, 128 };
var tc_13 = [_]u32{ 65536, 128, 256 };
var tc_14 = [_]u32{ 65536, 128, 65536 };
var tc_15 = [_]u32{ 65536, 129 };
var tc_16 = [_]u32{ 65536, 65536, 256 };
var tc_17 = [_]u32{ 65536, 65536, 65536 };
const test_cases = [_][]u32{
&tc_01, &tc_02, &tc_03, &tc_04, &tc_05, &tc_06, &tc_07, &tc_08, &tc_09, &tc_10,
&tc_11, &tc_12, &tc_13, &tc_14, &tc_15, &tc_16, &tc_17,
};
for (test_cases) |tc| {
const firsts = [_]u32{ 1, 65534, 65535, 65536, 65537, 131072 };
for (firsts) |first_n| {
tc[0] = first_n;
const to_flush = [_]bool{ false, true };
for (to_flush) |flush| {
var compressed = ArrayList(u8).init(testing.allocator);
defer compressed.deinit();
var want = ArrayList(u8).init(testing.allocator);
defer want.deinit();
var comp = try deflate.compressor(
testing.allocator,
compressed.writer(),
.{ .level = .best_speed },
);
defer comp.deinit();
for (tc) |n| {
try want.appendSlice(abcabc[0..n]);
try comp.writer().writeAll(abcabc[0..n]);
if (flush) {
try comp.flush();
}
}
try comp.close();
const decompressed = try testing.allocator.alloc(u8, want.items.len);
defer testing.allocator.free(decompressed);
var fib = io.fixedBufferStream(compressed.items);
var decomp = try inflate.decompressor(testing.allocator, fib.reader(), null);
defer decomp.deinit();
const read = try decomp.reader().readAll(decompressed);
try decomp.close();
try testing.expectEqual(want.items.len, read);
try testing.expectEqualSlices(u8, want.items, decompressed);
}
}
}
}
test "best speed max match offset" {
const abc = "abcdefgh";
const xyz = "stuvwxyz";
const input_margin = 16 - 1;
const match_before = [_]bool{ false, true };
for (match_before) |do_match_before| {
const extras = [_]u32{
0,
input_margin - 1,
input_margin,
input_margin + 1,
2 * input_margin,
};
for (extras) |extra| {
var offset_adj: i32 = -5;
while (offset_adj <= 5) : (offset_adj += 1) {
const offset = deflate_const.max_match_offset + offset_adj;
// Make src to be a []u8 of the form
// fmt("{s}{s}{s}{s}{s}", .{abc, zeros0, xyzMaybe, abc, zeros1})
// where:
// zeros0 is approximately max_match_offset zeros.
// xyzMaybe is either xyz or the empty string.
// zeros1 is between 0 and 30 zeros.
// The difference between the two abc's will be offset, which
// is max_match_offset plus or minus a small adjustment.
const src_len: usize = @as(usize, @intCast(offset + @as(i32, abc.len) + @as(i32, @intCast(extra))));
var src = try testing.allocator.alloc(u8, src_len);
defer testing.allocator.free(src);
@memcpy(src[0..abc.len], abc);
if (!do_match_before) {
const src_offset: usize = @as(usize, @intCast(offset - @as(i32, xyz.len)));
@memcpy(src[src_offset..][0..xyz.len], xyz);
}
const src_offset: usize = @as(usize, @intCast(offset));
@memcpy(src[src_offset..][0..abc.len], abc);
var compressed = ArrayList(u8).init(testing.allocator);
defer compressed.deinit();
var comp = try deflate.compressor(
testing.allocator,
compressed.writer(),
.{ .level = .best_speed },
);
defer comp.deinit();
try comp.writer().writeAll(src);
_ = try comp.close();
const decompressed = try testing.allocator.alloc(u8, src.len);
defer testing.allocator.free(decompressed);
var fib = io.fixedBufferStream(compressed.items);
var decomp = try inflate.decompressor(testing.allocator, fib.reader(), null);
defer decomp.deinit();
const read = try decomp.reader().readAll(decompressed);
try decomp.close();
try testing.expectEqual(src.len, read);
try testing.expectEqualSlices(u8, src, decompressed);
}
}
}
}

423
lib/std/compress/deflate/dict_decoder.zig
View File

@@ -1,423 +0,0 @@
const std = @import("std");
const assert = std.debug.assert;
const mem = std.mem;
const Allocator = std.mem.Allocator;
// Implements the LZ77 sliding dictionary as used in decompression.
// LZ77 decompresses data through sequences of two forms of commands:
//
// * Literal insertions: Runs of one or more symbols are inserted into the data
// stream as is. This is accomplished through the writeByte method for a
// single symbol, or combinations of writeSlice/writeMark for multiple symbols.
// Any valid stream must start with a literal insertion if no preset dictionary
// is used.
//
// * Backward copies: Runs of one or more symbols are copied from previously
// emitted data. Backward copies come as the tuple (dist, length) where dist
// determines how far back in the stream to copy from and length determines how
// many bytes to copy. Note that it is valid for the length to be greater than
// the distance. Since LZ77 uses forward copies, that situation is used to
// perform a form of run-length encoding on repeated runs of symbols.
// The writeCopy and tryWriteCopy are used to implement this command.
//
// For performance reasons, this implementation performs little to no sanity
// checks about the arguments. As such, the invariants documented for each
// method call must be respected.
pub const DictDecoder = struct {
const Self = @This();
allocator: Allocator = undefined,
hist: []u8 = undefined, // Sliding window history
// Invariant: 0 <= rd_pos <= wr_pos <= hist.len
wr_pos: u32 = 0, // Current output position in buffer
rd_pos: u32 = 0, // Have emitted hist[0..rd_pos] already
full: bool = false, // Has a full window length been written yet?
// init initializes DictDecoder to have a sliding window dictionary of the given
// size. If a preset dict is provided, it will initialize the dictionary with
// the contents of dict.
pub fn init(self: *Self, allocator: Allocator, size: u32, dict: ?[]const u8) !void {
self.allocator = allocator;
self.hist = try allocator.alloc(u8, size);
self.wr_pos = 0;
if (dict != null) {
const src = dict.?[dict.?.len -| self.hist.len..];
@memcpy(self.hist[0..src.len], src);
self.wr_pos = @as(u32, @intCast(dict.?.len));
}
if (self.wr_pos == self.hist.len) {
self.wr_pos = 0;
self.full = true;
}
self.rd_pos = self.wr_pos;
}
pub fn deinit(self: *Self) void {
self.allocator.free(self.hist);
}
// Reports the total amount of historical data in the dictionary.
pub fn histSize(self: *Self) u32 {
if (self.full) {
return @as(u32, @intCast(self.hist.len));
}
return self.wr_pos;
}
// Reports the number of bytes that can be flushed by readFlush.
pub fn availRead(self: *Self) u32 {
return self.wr_pos - self.rd_pos;
}
// Reports the available amount of output buffer space.
pub fn availWrite(self: *Self) u32 {
return @as(u32, @intCast(self.hist.len - self.wr_pos));
}
// Returns a slice of the available buffer to write data to.
//
// This invariant will be kept: s.len <= availWrite()
pub fn writeSlice(self: *Self) []u8 {
return self.hist[self.wr_pos..];
}
// Advances the writer pointer by `count`.
//
// This invariant must be kept: 0 <= count <= availWrite()
pub fn writeMark(self: *Self, count: u32) void {
assert(0 <= count and count <= self.availWrite());
self.wr_pos += count;
}
// Writes a single byte to the dictionary.
//
// This invariant must be kept: 0 < availWrite()
pub fn writeByte(self: *Self, byte: u8) void {
self.hist[self.wr_pos] = byte;
self.wr_pos += 1;
}
/// TODO: eliminate this function because the callsites should care about whether
/// or not their arguments alias and then they should directly call `@memcpy` or
/// `mem.copyForwards`.
fn copy(dst: []u8, src: []const u8) u32 {
if (src.len > dst.len) {
mem.copyForwards(u8, dst, src[0..dst.len]);
return @as(u32, @intCast(dst.len));
}
mem.copyForwards(u8, dst[0..src.len], src);
return @as(u32, @intCast(src.len));
}
// Copies a string at a given (dist, length) to the output.
// This returns the number of bytes copied and may be less than the requested
// length if the available space in the output buffer is too small.
//
// This invariant must be kept: 0 < dist <= histSize()
pub fn writeCopy(self: *Self, dist: u32, length: u32) u32 {
assert(0 < dist and dist <= self.histSize());
const dst_base = self.wr_pos;
var dst_pos = dst_base;
var src_pos: i32 = @as(i32, @intCast(dst_pos)) - @as(i32, @intCast(dist));
var end_pos = dst_pos + length;
if (end_pos > self.hist.len) {
end_pos = @as(u32, @intCast(self.hist.len));
}
// Copy non-overlapping section after destination position.
//
// This section is non-overlapping in that the copy length for this section
// is always less than or equal to the backwards distance. This can occur
// if a distance refers to data that wraps-around in the buffer.
// Thus, a backwards copy is performed here; that is, the exact bytes in
// the source prior to the copy is placed in the destination.
if (src_pos < 0) {
src_pos += @as(i32, @intCast(self.hist.len));
dst_pos += copy(self.hist[dst_pos..end_pos], self.hist[@as(usize, @intCast(src_pos))..]);
src_pos = 0;
}
// Copy possibly overlapping section before destination position.
//
// This section can overlap if the copy length for this section is larger
// than the backwards distance. This is allowed by LZ77 so that repeated
// strings can be succinctly represented using (dist, length) pairs.
// Thus, a forwards copy is performed here; that is, the bytes copied is
// possibly dependent on the resulting bytes in the destination as the copy
// progresses along. This is functionally equivalent to the following:
//
// var i = 0;
// while(i < end_pos - dst_pos) : (i+=1) {
// self.hist[dst_pos+i] = self.hist[src_pos+i];
// }
// dst_pos = end_pos;
//
while (dst_pos < end_pos) {
dst_pos += copy(self.hist[dst_pos..end_pos], self.hist[@as(usize, @intCast(src_pos))..dst_pos]);
}
self.wr_pos = dst_pos;
return dst_pos - dst_base;
}
// Tries to copy a string at a given (distance, length) to the
// output. This specialized version is optimized for short distances.
//
// This method is designed to be inlined for performance reasons.
//
// This invariant must be kept: 0 < dist <= histSize()
pub fn tryWriteCopy(self: *Self, dist: u32, length: u32) u32 {
var dst_pos = self.wr_pos;
const end_pos = dst_pos + length;
if (dst_pos < dist or end_pos > self.hist.len) {
return 0;
}
const dst_base = dst_pos;
const src_pos = dst_pos - dist;
// Copy possibly overlapping section before destination position.
while (dst_pos < end_pos) {
dst_pos += copy(self.hist[dst_pos..end_pos], self.hist[src_pos..dst_pos]);
}
self.wr_pos = dst_pos;
return dst_pos - dst_base;
}
// Returns a slice of the historical buffer that is ready to be
// emitted to the user. The data returned by readFlush must be fully consumed
// before calling any other DictDecoder methods.
pub fn readFlush(self: *Self) []u8 {
const to_read = self.hist[self.rd_pos..self.wr_pos];
self.rd_pos = self.wr_pos;
if (self.wr_pos == self.hist.len) {
self.wr_pos = 0;
self.rd_pos = 0;
self.full = true;
}
return to_read;
}
};
// tests
test "dictionary decoder" {
const ArrayList = std.ArrayList;
const testing = std.testing;
const abc = "ABC\n";
const fox = "The quick brown fox jumped over the lazy dog!\n";
const poem: []const u8 =
\\The Road Not Taken
\\Robert Frost
\\
\\Two roads diverged in a yellow wood,
\\And sorry I could not travel both
\\And be one traveler, long I stood
\\And looked down one as far as I could
\\To where it bent in the undergrowth;
\\
\\Then took the other, as just as fair,
\\And having perhaps the better claim,
\\Because it was grassy and wanted wear;
\\Though as for that the passing there
\\Had worn them really about the same,
\\
\\And both that morning equally lay
\\In leaves no step had trodden black.
\\Oh, I kept the first for another day!
\\Yet knowing how way leads on to way,
\\I doubted if I should ever come back.
\\
\\I shall be telling this with a sigh
\\Somewhere ages and ages hence:
\\Two roads diverged in a wood, and I-
\\I took the one less traveled by,
\\And that has made all the difference.
\\
;
const uppercase: []const u8 =
\\THE ROAD NOT TAKEN
\\ROBERT FROST
\\
\\TWO ROADS DIVERGED IN A YELLOW WOOD,
\\AND SORRY I COULD NOT TRAVEL BOTH
\\AND BE ONE TRAVELER, LONG I STOOD
\\AND LOOKED DOWN ONE AS FAR AS I COULD
\\TO WHERE IT BENT IN THE UNDERGROWTH;
\\
\\THEN TOOK THE OTHER, AS JUST AS FAIR,
\\AND HAVING PERHAPS THE BETTER CLAIM,
\\BECAUSE IT WAS GRASSY AND WANTED WEAR;
\\THOUGH AS FOR THAT THE PASSING THERE
\\HAD WORN THEM REALLY ABOUT THE SAME,
\\
\\AND BOTH THAT MORNING EQUALLY LAY
\\IN LEAVES NO STEP HAD TRODDEN BLACK.
\\OH, I KEPT THE FIRST FOR ANOTHER DAY!
\\YET KNOWING HOW WAY LEADS ON TO WAY,
\\I DOUBTED IF I SHOULD EVER COME BACK.
\\
\\I SHALL BE TELLING THIS WITH A SIGH
\\SOMEWHERE AGES AND AGES HENCE:
\\TWO ROADS DIVERGED IN A WOOD, AND I-
\\I TOOK THE ONE LESS TRAVELED BY,
\\AND THAT HAS MADE ALL THE DIFFERENCE.
\\
;
const PoemRefs = struct {
dist: u32, // Backward distance (0 if this is an insertion)
length: u32, // Length of copy or insertion
};
const poem_refs = [_]PoemRefs{
.{ .dist = 0, .length = 38 }, .{ .dist = 33, .length = 3 }, .{ .dist = 0, .length = 48 },
.{ .dist = 79, .length = 3 }, .{ .dist = 0, .length = 11 }, .{ .dist = 34, .length = 5 },
.{ .dist = 0, .length = 6 }, .{ .dist = 23, .length = 7 }, .{ .dist = 0, .length = 8 },
.{ .dist = 50, .length = 3 }, .{ .dist = 0, .length = 2 }, .{ .dist = 69, .length = 3 },
.{ .dist = 34, .length = 5 }, .{ .dist = 0, .length = 4 }, .{ .dist = 97, .length = 3 },
.{ .dist = 0, .length = 4 }, .{ .dist = 43, .length = 5 }, .{ .dist = 0, .length = 6 },
.{ .dist = 7, .length = 4 }, .{ .dist = 88, .length = 7 }, .{ .dist = 0, .length = 12 },
.{ .dist = 80, .length = 3 }, .{ .dist = 0, .length = 2 }, .{ .dist = 141, .length = 4 },
.{ .dist = 0, .length = 1 }, .{ .dist = 196, .length = 3 }, .{ .dist = 0, .length = 3 },
.{ .dist = 157, .length = 3 }, .{ .dist = 0, .length = 6 }, .{ .dist = 181, .length = 3 },
.{ .dist = 0, .length = 2 }, .{ .dist = 23, .length = 3 }, .{ .dist = 77, .length = 3 },
.{ .dist = 28, .length = 5 }, .{ .dist = 128, .length = 3 }, .{ .dist = 110, .length = 4 },
.{ .dist = 70, .length = 3 }, .{ .dist = 0, .length = 4 }, .{ .dist = 85, .length = 6 },
.{ .dist = 0, .length = 2 }, .{ .dist = 182, .length = 6 }, .{ .dist = 0, .length = 4 },
.{ .dist = 133, .length = 3 }, .{ .dist = 0, .length = 7 }, .{ .dist = 47, .length = 5 },
.{ .dist = 0, .length = 20 }, .{ .dist = 112, .length = 5 }, .{ .dist = 0, .length = 1 },
.{ .dist = 58, .length = 3 }, .{ .dist = 0, .length = 8 }, .{ .dist = 59, .length = 3 },
.{ .dist = 0, .length = 4 }, .{ .dist = 173, .length = 3 }, .{ .dist = 0, .length = 5 },
.{ .dist = 114, .length = 3 }, .{ .dist = 0, .length = 4 }, .{ .dist = 92, .length = 5 },
.{ .dist = 0, .length = 2 }, .{ .dist = 71, .length = 3 }, .{ .dist = 0, .length = 2 },
.{ .dist = 76, .length = 5 }, .{ .dist = 0, .length = 1 }, .{ .dist = 46, .length = 3 },
.{ .dist = 96, .length = 4 }, .{ .dist = 130, .length = 4 }, .{ .dist = 0, .length = 3 },
.{ .dist = 360, .length = 3 }, .{ .dist = 0, .length = 3 }, .{ .dist = 178, .length = 5 },
.{ .dist = 0, .length = 7 }, .{ .dist = 75, .length = 3 }, .{ .dist = 0, .length = 3 },
.{ .dist = 45, .length = 6 }, .{ .dist = 0, .length = 6 }, .{ .dist = 299, .length = 6 },
.{ .dist = 180, .length = 3 }, .{ .dist = 70, .length = 6 }, .{ .dist = 0, .length = 1 },
.{ .dist = 48, .length = 3 }, .{ .dist = 66, .length = 4 }, .{ .dist = 0, .length = 3 },
.{ .dist = 47, .length = 5 }, .{ .dist = 0, .length = 9 }, .{ .dist = 325, .length = 3 },
.{ .dist = 0, .length = 1 }, .{ .dist = 359, .length = 3 }, .{ .dist = 318, .length = 3 },
.{ .dist = 0, .length = 2 }, .{ .dist = 199, .length = 3 }, .{ .dist = 0, .length = 1 },
.{ .dist = 344, .length = 3 }, .{ .dist = 0, .length = 3 }, .{ .dist = 248, .length = 3 },
.{ .dist = 0, .length = 10 }, .{ .dist = 310, .length = 3 }, .{ .dist = 0, .length = 3 },
.{ .dist = 93, .length = 6 }, .{ .dist = 0, .length = 3 }, .{ .dist = 252, .length = 3 },
.{ .dist = 157, .length = 4 }, .{ .dist = 0, .length = 2 }, .{ .dist = 273, .length = 5 },
.{ .dist = 0, .length = 14 }, .{ .dist = 99, .length = 4 }, .{ .dist = 0, .length = 1 },
.{ .dist = 464, .length = 4 }, .{ .dist = 0, .length = 2 }, .{ .dist = 92, .length = 4 },
.{ .dist = 495, .length = 3 }, .{ .dist = 0, .length = 1 }, .{ .dist = 322, .length = 4 },
.{ .dist = 16, .length = 4 }, .{ .dist = 0, .length = 3 }, .{ .dist = 402, .length = 3 },
.{ .dist = 0, .length = 2 }, .{ .dist = 237, .length = 4 }, .{ .dist = 0, .length = 2 },
.{ .dist = 432, .length = 4 }, .{ .dist = 0, .length = 1 }, .{ .dist = 483, .length = 5 },
.{ .dist = 0, .length = 2 }, .{ .dist = 294, .length = 4 }, .{ .dist = 0, .length = 2 },
.{ .dist = 306, .length = 3 }, .{ .dist = 113, .length = 5 }, .{ .dist = 0, .length = 1 },
.{ .dist = 26, .length = 4 }, .{ .dist = 164, .length = 3 }, .{ .dist = 488, .length = 4 },
.{ .dist = 0, .length = 1 }, .{ .dist = 542, .length = 3 }, .{ .dist = 248, .length = 6 },
.{ .dist = 0, .length = 5 }, .{ .dist = 205, .length = 3 }, .{ .dist = 0, .length = 8 },
.{ .dist = 48, .length = 3 }, .{ .dist = 449, .length = 6 }, .{ .dist = 0, .length = 2 },
.{ .dist = 192, .length = 3 }, .{ .dist = 328, .length = 4 }, .{ .dist = 9, .length = 5 },
.{ .dist = 433, .length = 3 }, .{ .dist = 0, .length = 3 }, .{ .dist = 622, .length = 25 },
.{ .dist = 615, .length = 5 }, .{ .dist = 46, .length = 5 }, .{ .dist = 0, .length = 2 },
.{ .dist = 104, .length = 3 }, .{ .dist = 475, .length = 10 }, .{ .dist = 549, .length = 3 },
.{ .dist = 0, .length = 4 }, .{ .dist = 597, .length = 8 }, .{ .dist = 314, .length = 3 },
.{ .dist = 0, .length = 1 }, .{ .dist = 473, .length = 6 }, .{ .dist = 317, .length = 5 },
.{ .dist = 0, .length = 1 }, .{ .dist = 400, .length = 3 }, .{ .dist = 0, .length = 3 },
.{ .dist = 109, .length = 3 }, .{ .dist = 151, .length = 3 }, .{ .dist = 48, .length = 4 },
.{ .dist = 0, .length = 4 }, .{ .dist = 125, .length = 3 }, .{ .dist = 108, .length = 3 },
.{ .dist = 0, .length = 2 },
};
var got_list = ArrayList(u8).init(testing.allocator);
defer got_list.deinit();
var got = got_list.writer();
var want_list = ArrayList(u8).init(testing.allocator);
defer want_list.deinit();
var want = want_list.writer();
var dd = DictDecoder{};
try dd.init(testing.allocator, 1 << 11, null);
defer dd.deinit();
const util = struct {
fn writeCopy(dst_dd: *DictDecoder, dst: anytype, dist: u32, length: u32) !void {
var len = length;
while (len > 0) {
var n = dst_dd.tryWriteCopy(dist, len);
if (n == 0) {
n = dst_dd.writeCopy(dist, len);
}
len -= n;
if (dst_dd.availWrite() == 0) {
_ = try dst.write(dst_dd.readFlush());
}
}
}
fn writeString(dst_dd: *DictDecoder, dst: anytype, str: []const u8) !void {
var string = str;
while (string.len > 0) {
const cnt = DictDecoder.copy(dst_dd.writeSlice(), string);
dst_dd.writeMark(cnt);
string = string[cnt..];
if (dst_dd.availWrite() == 0) {
_ = try dst.write(dst_dd.readFlush());
}
}
}
};
try util.writeString(&dd, got, ".");
_ = try want.write(".");
var str = poem;
for (poem_refs, 0..) |ref, i| {
_ = i;
if (ref.dist == 0) {
try util.writeString(&dd, got, str[0..ref.length]);
} else {
try util.writeCopy(&dd, got, ref.dist, ref.length);
}
str = str[ref.length..];
}
_ = try want.write(poem);
try util.writeCopy(&dd, got, dd.histSize(), 33);
_ = try want.write(want_list.items[0..33]);
try util.writeString(&dd, got, abc);
try util.writeCopy(&dd, got, abc.len, 59 * abc.len);
_ = try want.write(abc ** 60);
try util.writeString(&dd, got, fox);
try util.writeCopy(&dd, got, fox.len, 9 * fox.len);
_ = try want.write(fox ** 10);
try util.writeString(&dd, got, ".");
try util.writeCopy(&dd, got, 1, 9);
_ = try want.write("." ** 10);
try util.writeString(&dd, got, uppercase);
try util.writeCopy(&dd, got, uppercase.len, 7 * uppercase.len);
var i: u8 = 0;
while (i < 8) : (i += 1) {
_ = try want.write(uppercase);
}
try util.writeCopy(&dd, got, dd.histSize(), 10);
_ = try want.write(want_list.items[want_list.items.len - dd.histSize() ..][0..10]);
_ = try got.write(dd.readFlush());
try testing.expectEqualSlices(u8, want_list.items, got_list.items);
}

1686
lib/std/compress/deflate/huffman_bit_writer.zig
View File

File diff suppressed because it is too large Load Diff

432
lib/std/compress/deflate/huffman_code.zig
View File

@@ -1,432 +0,0 @@
const std = @import("std");
const assert = std.debug.assert;
const math = std.math;
const mem = std.mem;
const sort = std.sort;
const testing = std.testing;
const Allocator = std.mem.Allocator;
const bu = @import("bits_utils.zig");
const deflate_const = @import("deflate_const.zig");
const max_bits_limit = 16;
const LiteralNode = struct {
literal: u16,
freq: u16,
};
// Describes the state of the constructed tree for a given depth.
const LevelInfo = struct {
// Our level. for better printing
level: u32,
// The frequency of the last node at this level
last_freq: u32,
// The frequency of the next character to add to this level
next_char_freq: u32,
// The frequency of the next pair (from level below) to add to this level.
// Only valid if the "needed" value of the next lower level is 0.
next_pair_freq: u32,
// The number of chains remaining to generate for this level before moving
// up to the next level
needed: u32,
};
// hcode is a huffman code with a bit code and bit length.
pub const HuffCode = struct {
code: u16 = 0,
len: u16 = 0,
// set sets the code and length of an hcode.
fn set(self: *HuffCode, code: u16, length: u16) void {
self.len = length;
self.code = code;
}
};
pub const HuffmanEncoder = struct {
codes: []HuffCode,
freq_cache: []LiteralNode = undefined,
bit_count: [17]u32 = undefined,
lns: []LiteralNode = undefined, // sorted by literal, stored to avoid repeated allocation in generate
lfs: []LiteralNode = undefined, // sorted by frequency, stored to avoid repeated allocation in generate
allocator: Allocator,
pub fn deinit(self: *HuffmanEncoder) void {
self.allocator.free(self.codes);
self.allocator.free(self.freq_cache);
}
// Update this Huffman Code object to be the minimum code for the specified frequency count.
//
// freq An array of frequencies, in which frequency[i] gives the frequency of literal i.
// max_bits The maximum number of bits to use for any literal.
pub fn generate(self: *HuffmanEncoder, freq: []u16, max_bits: u32) void {
var list = self.freq_cache[0 .. freq.len + 1];
// Number of non-zero literals
var count: u32 = 0;
// Set list to be the set of all non-zero literals and their frequencies
for (freq, 0..) |f, i| {
if (f != 0) {
list[count] = LiteralNode{ .literal = @as(u16, @intCast(i)), .freq = f };
count += 1;
} else {
list[count] = LiteralNode{ .literal = 0x00, .freq = 0 };
self.codes[i].len = 0;
}
}
list[freq.len] = LiteralNode{ .literal = 0x00, .freq = 0 };
list = list[0..count];
if (count <= 2) {
// Handle the small cases here, because they are awkward for the general case code. With
// two or fewer literals, everything has bit length 1.
for (list, 0..) |node, i| {
// "list" is in order of increasing literal value.
self.codes[node.literal].set(@as(u16, @intCast(i)), 1);
}
return;
}
self.lfs = list;
mem.sort(LiteralNode, self.lfs, {}, byFreq);
// Get the number of literals for each bit count
const bit_count = self.bitCounts(list, max_bits);
// And do the assignment
self.assignEncodingAndSize(bit_count, list);
}
pub fn bitLength(self: *HuffmanEncoder, freq: []u16) u32 {
var total: u32 = 0;
for (freq, 0..) |f, i| {
if (f != 0) {
total += @as(u32, @intCast(f)) * @as(u32, @intCast(self.codes[i].len));
}
}
return total;
}
// Return the number of literals assigned to each bit size in the Huffman encoding
//
// This method is only called when list.len >= 3
// The cases of 0, 1, and 2 literals are handled by special case code.
//
// list: An array of the literals with non-zero frequencies
// and their associated frequencies. The array is in order of increasing
// frequency, and has as its last element a special element with frequency
// std.math.maxInt(i32)
//
// max_bits: The maximum number of bits that should be used to encode any literal.
// Must be less than 16.
//
// Returns an integer array in which array[i] indicates the number of literals
// that should be encoded in i bits.
fn bitCounts(self: *HuffmanEncoder, list: []LiteralNode, max_bits_to_use: usize) []u32 {
var max_bits = max_bits_to_use;
const n = list.len;
assert(max_bits < max_bits_limit);
// The tree can't have greater depth than n - 1, no matter what. This
// saves a little bit of work in some small cases
max_bits = @min(max_bits, n - 1);
// Create information about each of the levels.
// A bogus "Level 0" whose sole purpose is so that
// level1.prev.needed == 0. This makes level1.next_pair_freq
// be a legitimate value that never gets chosen.
var levels: [max_bits_limit]LevelInfo = mem.zeroes([max_bits_limit]LevelInfo);
// leaf_counts[i] counts the number of literals at the left
// of ancestors of the rightmost node at level i.
// leaf_counts[i][j] is the number of literals at the left
// of the level j ancestor.
var leaf_counts: [max_bits_limit][max_bits_limit]u32 = mem.zeroes([max_bits_limit][max_bits_limit]u32);
{
var level = @as(u32, 1);
while (level <= max_bits) : (level += 1) {
// For every level, the first two items are the first two characters.
// We initialize the levels as if we had already figured this out.
levels[level] = LevelInfo{
.level = level,
.last_freq = list[1].freq,
.next_char_freq = list[2].freq,
.next_pair_freq = list[0].freq + list[1].freq,
.needed = 0,
};
leaf_counts[level][level] = 2;
if (level == 1) {
levels[level].next_pair_freq = math.maxInt(i32);
}
}
}
// We need a total of 2*n - 2 items at top level and have already generated 2.
levels[max_bits].needed = 2 * @as(u32, @intCast(n)) - 4;
{
var level = max_bits;
while (true) {
var l = &levels[level];
if (l.next_pair_freq == math.maxInt(i32) and l.next_char_freq == math.maxInt(i32)) {
// We've run out of both leafs and pairs.
// End all calculations for this level.
// To make sure we never come back to this level or any lower level,
// set next_pair_freq impossibly large.
l.needed = 0;
levels[level + 1].next_pair_freq = math.maxInt(i32);
level += 1;
continue;
}
const prev_freq = l.last_freq;
if (l.next_char_freq < l.next_pair_freq) {
// The next item on this row is a leaf node.
const next = leaf_counts[level][level] + 1;
l.last_freq = l.next_char_freq;
// Lower leaf_counts are the same of the previous node.
leaf_counts[level][level] = next;
if (next >= list.len) {
l.next_char_freq = maxNode().freq;
} else {
l.next_char_freq = list[next].freq;
}
} else {
// The next item on this row is a pair from the previous row.
// next_pair_freq isn't valid until we generate two
// more values in the level below
l.last_freq = l.next_pair_freq;
// Take leaf counts from the lower level, except counts[level] remains the same.
@memcpy(leaf_counts[level][0..level], leaf_counts[level - 1][0..level]);
levels[l.level - 1].needed = 2;
}
l.needed -= 1;
if (l.needed == 0) {
// We've done everything we need to do for this level.
// Continue calculating one level up. Fill in next_pair_freq
// of that level with the sum of the two nodes we've just calculated on
// this level.
if (l.level == max_bits) {
// All done!
break;
}
levels[l.level + 1].next_pair_freq = prev_freq + l.last_freq;
level += 1;
} else {
// If we stole from below, move down temporarily to replenish it.
while (levels[level - 1].needed > 0) {
level -= 1;
if (level == 0) {
break;
}
}
}
}
}
// Somethings is wrong if at the end, the top level is null or hasn't used
// all of the leaves.
assert(leaf_counts[max_bits][max_bits] == n);
var bit_count = self.bit_count[0 .. max_bits + 1];
var bits: u32 = 1;
const counts = &leaf_counts[max_bits];
{
var level = max_bits;
while (level > 0) : (level -= 1) {
// counts[level] gives the number of literals requiring at least "bits"
// bits to encode.
bit_count[bits] = counts[level] - counts[level - 1];
bits += 1;
if (level == 0) {
break;
}
}
}
return bit_count;
}
// Look at the leaves and assign them a bit count and an encoding as specified
// in RFC 1951 3.2.2
fn assignEncodingAndSize(self: *HuffmanEncoder, bit_count: []u32, list_arg: []LiteralNode) void {
var code = @as(u16, 0);
var list = list_arg;
for (bit_count, 0..) |bits, n| {
code <<= 1;
if (n == 0 or bits == 0) {
continue;
}
// The literals list[list.len-bits] .. list[list.len-bits]
// are encoded using "bits" bits, and get the values
// code, code + 1, .... The code values are
// assigned in literal order (not frequency order).
const chunk = list[list.len - @as(u32, @intCast(bits)) ..];
self.lns = chunk;
mem.sort(LiteralNode, self.lns, {}, byLiteral);
for (chunk) |node| {
self.codes[node.literal] = HuffCode{
.code = bu.bitReverse(u16, code, @as(u5, @intCast(n))),
.len = @as(u16, @intCast(n)),
};
code += 1;
}
list = list[0 .. list.len - @as(u32, @intCast(bits))];
}
}
};
fn maxNode() LiteralNode {
return LiteralNode{
.literal = math.maxInt(u16),
.freq = math.maxInt(u16),
};
}
pub fn newHuffmanEncoder(allocator: Allocator, size: u32) !HuffmanEncoder {
return HuffmanEncoder{
.codes = try allocator.alloc(HuffCode, size),
// Allocate a reusable buffer with the longest possible frequency table.
// (deflate_const.max_num_frequencies).
.freq_cache = try allocator.alloc(LiteralNode, deflate_const.max_num_frequencies + 1),
.allocator = allocator,
};
}
// Generates a HuffmanCode corresponding to the fixed literal table
pub fn generateFixedLiteralEncoding(allocator: Allocator) !HuffmanEncoder {
const h = try newHuffmanEncoder(allocator, deflate_const.max_num_frequencies);
var codes = h.codes;
var ch: u16 = 0;
while (ch < deflate_const.max_num_frequencies) : (ch += 1) {
var bits: u16 = undefined;
var size: u16 = undefined;
switch (ch) {
0...143 => {
// size 8, 000110000 .. 10111111
bits = ch + 48;
size = 8;
},
144...255 => {
// size 9, 110010000 .. 111111111
bits = ch + 400 - 144;
size = 9;
},
256...279 => {
// size 7, 0000000 .. 0010111
bits = ch - 256;
size = 7;
},
else => {
// size 8, 11000000 .. 11000111
bits = ch + 192 - 280;
size = 8;
},
}
codes[ch] = HuffCode{ .code = bu.bitReverse(u16, bits, @as(u5, @intCast(size))), .len = size };
}
return h;
}
pub fn generateFixedOffsetEncoding(allocator: Allocator) !HuffmanEncoder {
const h = try newHuffmanEncoder(allocator, 30);
var codes = h.codes;
for (codes, 0..) |_, ch| {
codes[ch] = HuffCode{ .code = bu.bitReverse(u16, @as(u16, @intCast(ch)), 5), .len = 5 };
}
return h;
}
fn byLiteral(context: void, a: LiteralNode, b: LiteralNode) bool {
_ = context;
return a.literal < b.literal;
}
fn byFreq(context: void, a: LiteralNode, b: LiteralNode) bool {
_ = context;
if (a.freq == b.freq) {
return a.literal < b.literal;
}
return a.freq < b.freq;
}
test "generate a Huffman code from an array of frequencies" {
var freqs: [19]u16 = [_]u16{
8, // 0
1, // 1
1, // 2
2, // 3
5, // 4
10, // 5
9, // 6
1, // 7
0, // 8
0, // 9
0, // 10
0, // 11
0, // 12
0, // 13
0, // 14
0, // 15
1, // 16
3, // 17
5, // 18
};
var enc = try newHuffmanEncoder(testing.allocator, freqs.len);
defer enc.deinit();
enc.generate(freqs[0..], 7);
try testing.expectEqual(@as(u32, 141), enc.bitLength(freqs[0..]));
try testing.expectEqual(@as(usize, 3), enc.codes[0].len);
try testing.expectEqual(@as(usize, 6), enc.codes[1].len);
try testing.expectEqual(@as(usize, 6), enc.codes[2].len);
try testing.expectEqual(@as(usize, 5), enc.codes[3].len);
try testing.expectEqual(@as(usize, 3), enc.codes[4].len);
try testing.expectEqual(@as(usize, 2), enc.codes[5].len);
try testing.expectEqual(@as(usize, 2), enc.codes[6].len);
try testing.expectEqual(@as(usize, 6), enc.codes[7].len);
try testing.expectEqual(@as(usize, 0), enc.codes[8].len);
try testing.expectEqual(@as(usize, 0), enc.codes[9].len);
try testing.expectEqual(@as(usize, 0), enc.codes[10].len);
try testing.expectEqual(@as(usize, 0), enc.codes[11].len);
try testing.expectEqual(@as(usize, 0), enc.codes[12].len);
try testing.expectEqual(@as(usize, 0), enc.codes[13].len);
try testing.expectEqual(@as(usize, 0), enc.codes[14].len);
try testing.expectEqual(@as(usize, 0), enc.codes[15].len);
try testing.expectEqual(@as(usize, 6), enc.codes[16].len);
try testing.expectEqual(@as(usize, 5), enc.codes[17].len);
try testing.expectEqual(@as(usize, 3), enc.codes[18].len);
try testing.expectEqual(@as(u16, 0x0), enc.codes[5].code);
try testing.expectEqual(@as(u16, 0x2), enc.codes[6].code);
try testing.expectEqual(@as(u16, 0x1), enc.codes[0].code);
try testing.expectEqual(@as(u16, 0x5), enc.codes[4].code);
try testing.expectEqual(@as(u16, 0x3), enc.codes[18].code);
try testing.expectEqual(@as(u16, 0x7), enc.codes[3].code);
try testing.expectEqual(@as(u16, 0x17), enc.codes[17].code);
try testing.expectEqual(@as(u16, 0x0f), enc.codes[1].code);
try testing.expectEqual(@as(u16, 0x2f), enc.codes[2].code);
try testing.expectEqual(@as(u16, 0x1f), enc.codes[7].code);
try testing.expectEqual(@as(u16, 0x3f), enc.codes[16].code);
}
test "generate a Huffman code for the fixed literal table specific to Deflate" {
var enc = try generateFixedLiteralEncoding(testing.allocator);
defer enc.deinit();
}
test "generate a Huffman code for the 30 possible relative offsets (LZ77 distances) of Deflate" {
var enc = try generateFixedOffsetEncoding(testing.allocator);
defer enc.deinit();
}

1
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29
lib/std/compress/deflate/testdata/compress-gettysburg.txt vendored
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@@ -1,29 +0,0 @@
Four score and seven years ago our fathers brought forth on
this continent, a new nation, conceived in Liberty, and dedicated
to the proposition that all men are created equal.
Now we are engaged in a great Civil War, testing whether that
nation, or any nation so conceived and so dedicated, can long
endure.
We are met on a great battle-field of that war.
We have come to dedicate a portion of that field, as a final
resting place for those who here gave their lives that that
nation might live. It is altogether fitting and proper that
we should do this.
But, in a larger sense, we can not dedicate - we can not
consecrate - we can not hallow - this ground.
The brave men, living and dead, who struggled here, have
consecrated it, far above our poor power to add or detract.
The world will little note, nor long remember what we say here,
but it can never forget what they did here.
It is for us the living, rather, to be dedicated here to the
unfinished work which they who fought here have thus far so
nobly advanced. It is rather for us to be here dedicated to
the great task remaining before us - that from these honored
dead we take increased devotion to that cause for which they
gave the last full measure of devotion -
that we here highly resolve that these dead shall not have
died in vain - that this nation, under God, shall have a new
birth of freedom - and that government of the people, by the
people, for the people, shall not perish from this earth.
Abraham Lincoln, November 19, 1863, Gettysburg, Pennsylvania

1
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103
lib/std/compress/deflate/token.zig
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// 2 bits: type, can be 0 (literal), 1 (EOF), 2 (Match) or 3 (Unused).
// 8 bits: xlength (length - MIN_MATCH_LENGTH).
// 22 bits: xoffset (offset - MIN_OFFSET_SIZE), or literal.
const length_shift = 22;
const offset_mask = (1 << length_shift) - 1; // 4_194_303
const literal_type = 0 << 30; // 0
pub const match_type = 1 << 30; // 1_073_741_824
// The length code for length X (MIN_MATCH_LENGTH <= X <= MAX_MATCH_LENGTH)
// is length_codes[length - MIN_MATCH_LENGTH]
var length_codes = [_]u32{
0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
13, 13, 13, 13, 14, 14, 14, 14, 15, 15,
15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
19, 19, 19, 19, 20, 20, 20, 20, 20, 20,
20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 28,
};
var offset_codes = [_]u32{
0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
};
pub const Token = u32;
// Convert a literal into a literal token.
pub fn literalToken(lit: u32) Token {
return literal_type + lit;
}
// Convert a < xlength, xoffset > pair into a match token.
pub fn matchToken(xlength: u32, xoffset: u32) Token {
return match_type + (xlength << length_shift) + xoffset;
}
// Returns the literal of a literal token
pub fn literal(t: Token) u32 {
return @as(u32, @intCast(t - literal_type));
}
// Returns the extra offset of a match token
pub fn offset(t: Token) u32 {
return @as(u32, @intCast(t)) & offset_mask;
}
pub fn length(t: Token) u32 {
return @as(u32, @intCast((t - match_type) >> length_shift));
}
pub fn lengthCode(len: u32) u32 {
return length_codes[len];
}
// Returns the offset code corresponding to a specific offset
pub fn offsetCode(off: u32) u32 {
if (off < @as(u32, @intCast(offset_codes.len))) {
return offset_codes[off];
}
if (off >> 7 < @as(u32, @intCast(offset_codes.len))) {
return offset_codes[off >> 7] + 14;
}
return offset_codes[off >> 14] + 28;
}
test {
const std = @import("std");
try std.testing.expectEqual(@as(Token, 3_401_581_099), matchToken(555, 555));
}

481
lib/std/compress/flate.zig Normal file
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/// Deflate is a lossless data compression file format that uses a combination
/// of LZ77 and Huffman coding.
pub const deflate = @import("flate/deflate.zig");
/// Inflate is the decoding process that takes a Deflate bitstream for
/// decompression and correctly produces the original full-size data or file.
pub const inflate = @import("flate/inflate.zig");
/// Decompress compressed data from reader and write plain data to the writer.
pub fn decompress(reader: anytype, writer: anytype) !void {
try inflate.decompress(.raw, reader, writer);
}
/// Decompressor type
pub fn Decompressor(comptime ReaderType: type) type {
return inflate.Inflate(.raw, ReaderType);
}
/// Create Decompressor which will read compressed data from reader.
pub fn decompressor(reader: anytype) Decompressor(@TypeOf(reader)) {
return inflate.decompressor(.raw, reader);
}
/// Compression level, trades between speed and compression size.
pub const Options = deflate.Options;
/// Compress plain data from reader and write compressed data to the writer.
pub fn compress(reader: anytype, writer: anytype, options: Options) !void {
try deflate.compress(.raw, reader, writer, options);
}
/// Compressor type
pub fn Compressor(comptime WriterType: type) type {
return deflate.Compressor(.raw, WriterType);
}
/// Create Compressor which outputs compressed data to the writer.
pub fn compressor(writer: anytype, options: Options) !Compressor(@TypeOf(writer)) {
return try deflate.compressor(.raw, writer, options);
}
/// Huffman only compression. Without Lempel-Ziv match searching. Faster
/// compression, less memory requirements but bigger compressed sizes.
pub const huffman = struct {
pub fn compress(reader: anytype, writer: anytype) !void {
try deflate.huffman.compress(.raw, reader, writer);
}
pub fn Compressor(comptime WriterType: type) type {
return deflate.huffman.Compressor(.raw, WriterType);
}
pub fn compressor(writer: anytype) !huffman.Compressor(@TypeOf(writer)) {
return deflate.huffman.compressor(.raw, writer);
}
};
// No compression store only. Compressed size is slightly bigger than plain.
pub const store = struct {
pub fn compress(reader: anytype, writer: anytype) !void {
try deflate.store.compress(.raw, reader, writer);
}
pub fn Compressor(comptime WriterType: type) type {
return deflate.store.Compressor(.raw, WriterType);
}
pub fn compressor(writer: anytype) !store.Compressor(@TypeOf(writer)) {
return deflate.store.compressor(.raw, writer);
}
};
/// Container defines header/footer arround deflate bit stream. Gzip and zlib
/// compression algorithms are containers arround deflate bit stream body.
const Container = @import("flate/container.zig").Container;
const std = @import("std");
const testing = std.testing;
const fixedBufferStream = std.io.fixedBufferStream;
const print = std.debug.print;
const builtin = @import("builtin");
test "flate" {
_ = @import("flate/deflate.zig");
_ = @import("flate/inflate.zig");
}
test "flate compress/decompress" {
if (builtin.target.cpu.arch == .wasm32) return error.SkipZigTest;
var cmp_buf: [64 * 1024]u8 = undefined; // compressed data buffer
var dcm_buf: [64 * 1024]u8 = undefined; // decompressed data buffer
const levels = [_]deflate.Level{ .level_4, .level_5, .level_6, .level_7, .level_8, .level_9 };
const cases = [_]struct {
data: []const u8, // uncompressed content
// compressed data sizes per level 4-9
gzip_sizes: [levels.len]usize = [_]usize{0} ** levels.len,
huffman_only_size: usize = 0,
store_size: usize = 0,
}{
.{
.data = @embedFile("flate/testdata/rfc1951.txt"),
.gzip_sizes = [_]usize{ 11513, 11217, 11139, 11126, 11122, 11119 },
.huffman_only_size = 20287,
.store_size = 36967,
},
.{
.data = @embedFile("flate/testdata/fuzz/roundtrip1.input"),
.gzip_sizes = [_]usize{ 373, 370, 370, 370, 370, 370 },
.huffman_only_size = 393,
.store_size = 393,
},
.{
.data = @embedFile("flate/testdata/fuzz/roundtrip2.input"),
.gzip_sizes = [_]usize{ 373, 373, 373, 373, 373, 373 },
.huffman_only_size = 394,
.store_size = 394,
},
.{
.data = @embedFile("flate/testdata/fuzz/deflate-stream.expect"),
.gzip_sizes = [_]usize{ 351, 347, 347, 347, 347, 347 },
.huffman_only_size = 498,
.store_size = 747,
},
};
for (cases, 0..) |case, case_no| { // for each case
const data = case.data;
for (levels, 0..) |level, i| { // for each compression level
inline for (Container.list) |container| { // for each wrapping
var compressed_size: usize = if (case.gzip_sizes[i] > 0)
case.gzip_sizes[i] - Container.gzip.size() + container.size()
else
0;
// compress original stream to compressed stream
{
var original = fixedBufferStream(data);
var compressed = fixedBufferStream(&cmp_buf);
try deflate.compress(container, original.reader(), compressed.writer(), .{ .level = level });
if (compressed_size == 0) {
if (container == .gzip)
print("case {d} gzip level {} compressed size: {d}\n", .{ case_no, level, compressed.pos });
compressed_size = compressed.pos;
}
try testing.expectEqual(compressed_size, compressed.pos);
}
// decompress compressed stream to decompressed stream
{
var compressed = fixedBufferStream(cmp_buf[0..compressed_size]);
var decompressed = fixedBufferStream(&dcm_buf);
try inflate.decompress(container, compressed.reader(), decompressed.writer());
try testing.expectEqualSlices(u8, data, decompressed.getWritten());
}
// compressor writer interface
{
var compressed = fixedBufferStream(&cmp_buf);
var cmp = try deflate.compressor(container, compressed.writer(), .{ .level = level });
var cmp_wrt = cmp.writer();
try cmp_wrt.writeAll(data);
try cmp.finish();
try testing.expectEqual(compressed_size, compressed.pos);
}
// decompressor reader interface
{
var compressed = fixedBufferStream(cmp_buf[0..compressed_size]);
var dcm = inflate.decompressor(container, compressed.reader());
var dcm_rdr = dcm.reader();
const n = try dcm_rdr.readAll(&dcm_buf);
try testing.expectEqual(data.len, n);
try testing.expectEqualSlices(u8, data, dcm_buf[0..n]);
}
}
}
// huffman only compression
{
inline for (Container.list) |container| { // for each wrapping
var compressed_size: usize = if (case.huffman_only_size > 0)
case.huffman_only_size - Container.gzip.size() + container.size()
else
0;
// compress original stream to compressed stream
{
var original = fixedBufferStream(data);
var compressed = fixedBufferStream(&cmp_buf);
var cmp = try deflate.huffman.compressor(container, compressed.writer());
try cmp.compress(original.reader());
try cmp.finish();
if (compressed_size == 0) {
if (container == .gzip)
print("case {d} huffman only compressed size: {d}\n", .{ case_no, compressed.pos });
compressed_size = compressed.pos;
}
try testing.expectEqual(compressed_size, compressed.pos);
}
// decompress compressed stream to decompressed stream
{
var compressed = fixedBufferStream(cmp_buf[0..compressed_size]);
var decompressed = fixedBufferStream(&dcm_buf);
try inflate.decompress(container, compressed.reader(), decompressed.writer());
try testing.expectEqualSlices(u8, data, decompressed.getWritten());
}
}
}
// store only
{
inline for (Container.list) |container| { // for each wrapping
var compressed_size: usize = if (case.store_size > 0)
case.store_size - Container.gzip.size() + container.size()
else
0;
// compress original stream to compressed stream
{
var original = fixedBufferStream(data);
var compressed = fixedBufferStream(&cmp_buf);
var cmp = try deflate.store.compressor(container, compressed.writer());
try cmp.compress(original.reader());
try cmp.finish();
if (compressed_size == 0) {
if (container == .gzip)
print("case {d} store only compressed size: {d}\n", .{ case_no, compressed.pos });
compressed_size = compressed.pos;
}
try testing.expectEqual(compressed_size, compressed.pos);
}
// decompress compressed stream to decompressed stream
{
var compressed = fixedBufferStream(cmp_buf[0..compressed_size]);
var decompressed = fixedBufferStream(&dcm_buf);
try inflate.decompress(container, compressed.reader(), decompressed.writer());
try testing.expectEqualSlices(u8, data, decompressed.getWritten());
}
}
}
}
}
fn testDecompress(comptime container: Container, compressed: []const u8, expected_plain: []const u8) !void {
var in = fixedBufferStream(compressed);
var out = std.ArrayList(u8).init(testing.allocator);
defer out.deinit();
try inflate.decompress(container, in.reader(), out.writer());
try testing.expectEqualSlices(u8, expected_plain, out.items);
}
test "flate don't read past deflate stream's end" {
try testDecompress(.zlib, &[_]u8{
0x08, 0xd7, 0x63, 0xf8, 0xcf, 0xc0, 0xc0, 0x00, 0xc1, 0xff,
0xff, 0x43, 0x30, 0x03, 0x03, 0xc3, 0xff, 0xff, 0xff, 0x01,
0x83, 0x95, 0x0b, 0xf5,
}, &[_]u8{
0x00, 0xff, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0xff,
0x00, 0xff, 0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0x00, 0x00,
0x00, 0x00, 0xff, 0xff, 0xff,
});
}
test "flate zlib header" {
// Truncated header
try testing.expectError(
error.EndOfStream,
testDecompress(.zlib, &[_]u8{0x78}, ""),
);
// Wrong CM
try testing.expectError(
error.BadZlibHeader,
testDecompress(.zlib, &[_]u8{ 0x79, 0x94 }, ""),
);
// Wrong CINFO
try testing.expectError(
error.BadZlibHeader,
testDecompress(.zlib, &[_]u8{ 0x88, 0x98 }, ""),
);
// Wrong checksum
try testing.expectError(
error.WrongZlibChecksum,
testDecompress(.zlib, &[_]u8{ 0x78, 0xda, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00 }, ""),
);
// Truncated checksum
try testing.expectError(
error.EndOfStream,
testDecompress(.zlib, &[_]u8{ 0x78, 0xda, 0x03, 0x00, 0x00 }, ""),
);
}
test "flate gzip header" {
// Truncated header
try testing.expectError(
error.EndOfStream,
testDecompress(.gzip, &[_]u8{ 0x1f, 0x8B }, undefined),
);
// Wrong CM
try testing.expectError(
error.BadGzipHeader,
testDecompress(.gzip, &[_]u8{
0x1f, 0x8b, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x03,
}, undefined),
);
// Wrong checksum
try testing.expectError(
error.WrongGzipChecksum,
testDecompress(.gzip, &[_]u8{
0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x03, 0x03, 0x00, 0x00, 0x00, 0x00, 0x01,
0x00, 0x00, 0x00, 0x00,
}, undefined),
);
// Truncated checksum
try testing.expectError(
error.EndOfStream,
testDecompress(.gzip, &[_]u8{
0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x03, 0x03, 0x00, 0x00, 0x00, 0x00,
}, undefined),
);
// Wrong initial size
try testing.expectError(
error.WrongGzipSize,
testDecompress(.gzip, &[_]u8{
0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x03, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x01,
}, undefined),
);
// Truncated initial size field
try testing.expectError(
error.EndOfStream,
testDecompress(.gzip, &[_]u8{
0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x03, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00,
}, undefined),
);
try testDecompress(.gzip, &[_]u8{
// GZIP header
0x1f, 0x8b, 0x08, 0x12, 0x00, 0x09, 0x6e, 0x88, 0x00, 0xff, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x00,
// header.FHCRC (should cover entire header)
0x99, 0xd6,
// GZIP data
0x01, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
}, "");
}
test "flate public interface" {
if (builtin.target.cpu.arch == .wasm32) return error.SkipZigTest;
const plain_data = [_]u8{ 'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', 0x0a };
// deflate final stored block, header + plain (stored) data
const deflate_block = [_]u8{
0b0000_0001, 0b0000_1100, 0x00, 0b1111_0011, 0xff, // deflate fixed buffer header len, nlen
} ++ plain_data;
// gzip header/footer + deflate block
const gzip_data =
[_]u8{ 0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03 } ++ // gzip header (10 bytes)
deflate_block ++
[_]u8{ 0xd5, 0xe0, 0x39, 0xb7, 0x0c, 0x00, 0x00, 0x00 }; // gzip footer checksum (4 byte), size (4 bytes)
// zlib header/footer + deflate block
const zlib_data = [_]u8{ 0x78, 0b10_0_11100 } ++ // zlib header (2 bytes)}
deflate_block ++
[_]u8{ 0x1c, 0xf2, 0x04, 0x47 }; // zlib footer: checksum
const gzip = @import("gzip.zig");
const zlib = @import("zlib.zig");
const flate = @This();
try testInterface(gzip, &gzip_data, &plain_data);
try testInterface(zlib, &zlib_data, &plain_data);
try testInterface(flate, &deflate_block, &plain_data);
}
fn testInterface(comptime pkg: type, gzip_data: []const u8, plain_data: []const u8) !void {
var buffer1: [64]u8 = undefined;
var buffer2: [64]u8 = undefined;
var compressed = fixedBufferStream(&buffer1);
var plain = fixedBufferStream(&buffer2);
// decompress
{
var in = fixedBufferStream(gzip_data);
try pkg.decompress(in.reader(), plain.writer());
try testing.expectEqualSlices(u8, plain_data, plain.getWritten());
}
plain.reset();
compressed.reset();
// compress/decompress
{
var in = fixedBufferStream(plain_data);
try pkg.compress(in.reader(), compressed.writer(), .{});
compressed.reset();
try pkg.decompress(compressed.reader(), plain.writer());
try testing.expectEqualSlices(u8, plain_data, plain.getWritten());
}
plain.reset();
compressed.reset();
// compressor/decompressor
{
var in = fixedBufferStream(plain_data);
var cmp = try pkg.compressor(compressed.writer(), .{});
try cmp.compress(in.reader());
try cmp.finish();
compressed.reset();
var dcp = pkg.decompressor(compressed.reader());
try dcp.decompress(plain.writer());
try testing.expectEqualSlices(u8, plain_data, plain.getWritten());
}
plain.reset();
compressed.reset();
// huffman
{
// huffman compress/decompress
{
var in = fixedBufferStream(plain_data);
try pkg.huffman.compress(in.reader(), compressed.writer());
compressed.reset();
try pkg.decompress(compressed.reader(), plain.writer());
try testing.expectEqualSlices(u8, plain_data, plain.getWritten());
}
plain.reset();
compressed.reset();
// huffman compressor/decompressor
{
var in = fixedBufferStream(plain_data);
var cmp = try pkg.huffman.compressor(compressed.writer());
try cmp.compress(in.reader());
try cmp.finish();
compressed.reset();
try pkg.decompress(compressed.reader(), plain.writer());
try testing.expectEqualSlices(u8, plain_data, plain.getWritten());
}
}
plain.reset();
compressed.reset();
// store
{
// store compress/decompress
{
var in = fixedBufferStream(plain_data);
try pkg.store.compress(in.reader(), compressed.writer());
compressed.reset();
try pkg.decompress(compressed.reader(), plain.writer());
try testing.expectEqualSlices(u8, plain_data, plain.getWritten());
}
plain.reset();
compressed.reset();
// store compressor/decompressor
{
var in = fixedBufferStream(plain_data);
var cmp = try pkg.store.compressor(compressed.writer());
try cmp.compress(in.reader());
try cmp.finish();
compressed.reset();
try pkg.decompress(compressed.reader(), plain.writer());
try testing.expectEqualSlices(u8, plain_data, plain.getWritten());
}
}
}

234
lib/std/compress/flate/CircularBuffer.zig Normal file
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//! 64K buffer of uncompressed data created in inflate (decompression). Has enough
//! history to support writing match<length, distance>; copying length of bytes
//! from the position distance backward from current.
//!
//! Reads can return less than available bytes if they are spread across
//! different circles. So reads should repeat until get required number of bytes
//! or until returned slice is zero length.
//!
//! Note on deflate limits:
//! * non-compressible block is limited to 65,535 bytes.
//! * backward pointer is limited in distance to 32K bytes and in length to 258 bytes.
//!
//! Whole non-compressed block can be written without overlap. We always have
//! history of up to 64K, more then 32K needed.
//!
const std = @import("std");
const assert = std.debug.assert;
const testing = std.testing;
const consts = @import("consts.zig").match;
const mask = 0xffff; // 64K - 1
const buffer_len = mask + 1; // 64K buffer
const Self = @This();
buffer: [buffer_len]u8 = undefined,
wp: usize = 0, // write position
rp: usize = 0, // read position
fn writeAll(self: *Self, buf: []const u8) void {
for (buf) |c| self.write(c);
}
/// Write literal.
pub fn write(self: *Self, b: u8) void {
assert(self.wp - self.rp < mask);
self.buffer[self.wp & mask] = b;
self.wp += 1;
}
/// Write match (back-reference to the same data slice) starting at `distance`
/// back from current write position, and `length` of bytes.
pub fn writeMatch(self: *Self, length: u16, distance: u16) !void {
if (self.wp < distance or
length < consts.base_length or length > consts.max_length or
distance < consts.min_distance or distance > consts.max_distance)
{
return error.InvalidMatch;
}
assert(self.wp - self.rp < mask);
var from: usize = self.wp - distance;
const from_end: usize = from + length;
var to: usize = self.wp;
const to_end: usize = to + length;
self.wp += length;
// Fast path using memcpy
if (length <= distance and // no overlapping buffers
(from >> 16 == from_end >> 16) and // start and and at the same circle
(to >> 16 == to_end >> 16))
{
@memcpy(self.buffer[to & mask .. to_end & mask], self.buffer[from & mask .. from_end & mask]);
return;
}
// Slow byte by byte
while (to < to_end) {
self.buffer[to & mask] = self.buffer[from & mask];
to += 1;
from += 1;
}
}
/// Returns writable part of the internal buffer of size `n` at most. Advances
/// write pointer, assumes that returned buffer will be filled with data.
pub fn getWritable(self: *Self, n: usize) []u8 {
const wp = self.wp & mask;
const len = @min(n, buffer_len - wp);
self.wp += len;
return self.buffer[wp .. wp + len];
}
/// Read available data. Can return part of the available data if it is
/// spread across two circles. So read until this returns zero length.
pub fn read(self: *Self) []const u8 {
return self.readAtMost(buffer_len);
}
/// Read part of available data. Can return less than max even if there are
/// more than max decoded data.
pub fn readAtMost(self: *Self, limit: usize) []const u8 {
const rb = self.readBlock(if (limit == 0) buffer_len else limit);
defer self.rp += rb.len;
return self.buffer[rb.head..rb.tail];
}
const ReadBlock = struct {
head: usize,
tail: usize,
len: usize,
};
/// Returns position of continous read block data.
fn readBlock(self: *Self, max: usize) ReadBlock {
const r = self.rp & mask;
const w = self.wp & mask;
const n = @min(
max,
if (w >= r) w - r else buffer_len - r,
);
return .{
.head = r,
.tail = r + n,
.len = n,
};
}
/// Number of free bytes for write.
pub fn free(self: *Self) usize {
return buffer_len - (self.wp - self.rp);
}
/// Full if largest match can't fit. 258 is largest match length. That much
/// bytes can be produced in single decode step.
pub fn full(self: *Self) bool {
return self.free() < 258 + 1;
}
// example from: https://youtu.be/SJPvNi4HrWQ?t=3558
test "flate.CircularBuffer writeMatch" {
var cb: Self = .{};
cb.writeAll("a salad; ");
try cb.writeMatch(5, 9);
try cb.writeMatch(3, 3);
try testing.expectEqualStrings("a salad; a salsal", cb.read());
}
test "flate.CircularBuffer writeMatch overlap" {
var cb: Self = .{};
cb.writeAll("a b c ");
try cb.writeMatch(8, 4);
cb.write('d');
try testing.expectEqualStrings("a b c b c b c d", cb.read());
}
test "flate.CircularBuffer readAtMost" {
var cb: Self = .{};
cb.writeAll("0123456789");
try cb.writeMatch(50, 10);
try testing.expectEqualStrings("0123456789" ** 6, cb.buffer[cb.rp..cb.wp]);
for (0..6) |i| {
try testing.expectEqual(i * 10, cb.rp);
try testing.expectEqualStrings("0123456789", cb.readAtMost(10));
}
try testing.expectEqualStrings("", cb.readAtMost(10));
try testing.expectEqualStrings("", cb.read());
}
test "flate.CircularBuffer" {
var cb: Self = .{};
const data = "0123456789abcdef" ** (1024 / 16);
cb.writeAll(data);
try testing.expectEqual(@as(usize, 0), cb.rp);
try testing.expectEqual(@as(usize, 1024), cb.wp);
try testing.expectEqual(@as(usize, 1024 * 63), cb.free());
for (0..62 * 4) |_|
try cb.writeMatch(256, 1024); // write 62K
try testing.expectEqual(@as(usize, 0), cb.rp);
try testing.expectEqual(@as(usize, 63 * 1024), cb.wp);
try testing.expectEqual(@as(usize, 1024), cb.free());
cb.writeAll(data[0..200]);
_ = cb.readAtMost(1024); // make some space
cb.writeAll(data); // overflows write position
try testing.expectEqual(@as(usize, 200 + 65536), cb.wp);
try testing.expectEqual(@as(usize, 1024), cb.rp);
try testing.expectEqual(@as(usize, 1024 - 200), cb.free());
const rb = cb.readBlock(Self.buffer_len);
try testing.expectEqual(@as(usize, 65536 - 1024), rb.len);
try testing.expectEqual(@as(usize, 1024), rb.head);
try testing.expectEqual(@as(usize, 65536), rb.tail);
try testing.expectEqual(@as(usize, 65536 - 1024), cb.read().len); // read to the end of the buffer
try testing.expectEqual(@as(usize, 200 + 65536), cb.wp);
try testing.expectEqual(@as(usize, 65536), cb.rp);
try testing.expectEqual(@as(usize, 65536 - 200), cb.free());
try testing.expectEqual(@as(usize, 200), cb.read().len); // read the rest
}
test "flate.CircularBuffer write overlap" {
var cb: Self = .{};
cb.wp = cb.buffer.len - 15;
cb.rp = cb.wp;
cb.writeAll("0123456789");
cb.writeAll("abcdefghij");
try testing.expectEqual(cb.buffer.len + 5, cb.wp);
try testing.expectEqual(cb.buffer.len - 15, cb.rp);
try testing.expectEqualStrings("0123456789abcde", cb.read());
try testing.expectEqualStrings("fghij", cb.read());
try testing.expect(cb.wp == cb.rp);
}
test "flate.CircularBuffer writeMatch/read overlap" {
var cb: Self = .{};
cb.wp = cb.buffer.len - 15;
cb.rp = cb.wp;
cb.writeAll("0123456789");
try cb.writeMatch(15, 5);
try testing.expectEqualStrings("012345678956789", cb.read());
try testing.expectEqualStrings("5678956789", cb.read());
try cb.writeMatch(20, 25);
try testing.expectEqualStrings("01234567895678956789", cb.read());
}

125
lib/std/compress/flate/Lookup.zig Normal file
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/// Lookup of the previous locations for the same 4 byte data. Works on hash of
/// 4 bytes data. Head contains position of the first match for each hash. Chain
/// points to the previous position of the same hash given the current location.
///
const std = @import("std");
const testing = std.testing;
const expect = testing.expect;
const consts = @import("consts.zig");
const Self = @This();
const prime4 = 0x9E3779B1; // 4 bytes prime number 2654435761
const chain_len = 2 * consts.history.len;
// Maps hash => first position
head: [consts.lookup.len]u16 = [_]u16{0} ** consts.lookup.len,
// Maps position => previous positions for the same hash value
chain: [chain_len]u16 = [_]u16{0} ** (chain_len),
// Calculates hash of the 4 bytes from data.
// Inserts `pos` position of that hash in the lookup tables.
// Returns previous location with the same hash value.
pub fn add(self: *Self, data: []const u8, pos: u16) u16 {
if (data.len < 4) return 0;
const h = hash(data[0..4]);
return self.set(h, pos);
}
// Retruns previous location with the same hash value given the current
// position.
pub fn prev(self: *Self, pos: u16) u16 {
return self.chain[pos];
}
fn set(self: *Self, h: u32, pos: u16) u16 {
const p = self.head[h];
self.head[h] = pos;
self.chain[pos] = p;
return p;
}
// Slide all positions in head and chain for `n`
pub fn slide(self: *Self, n: u16) void {
for (&self.head) |*v| {
v.* -|= n;
}
var i: usize = 0;
while (i < n) : (i += 1) {
self.chain[i] = self.chain[i + n] -| n;
}
}
// Add `len` 4 bytes hashes from `data` into lookup.
// Position of the first byte is `pos`.
pub fn bulkAdd(self: *Self, data: []const u8, len: u16, pos: u16) void {
if (len == 0 or data.len < consts.match.min_length) {
return;
}
var hb =
@as(u32, data[3]) |
@as(u32, data[2]) << 8 |
@as(u32, data[1]) << 16 |
@as(u32, data[0]) << 24;
_ = self.set(hashu(hb), pos);
var i = pos;
for (4..@min(len + 3, data.len)) |j| {
hb = (hb << 8) | @as(u32, data[j]);
i += 1;
_ = self.set(hashu(hb), i);
}
}
// Calculates hash of the first 4 bytes of `b`.
fn hash(b: *const [4]u8) u32 {
return hashu(@as(u32, b[3]) |
@as(u32, b[2]) << 8 |
@as(u32, b[1]) << 16 |
@as(u32, b[0]) << 24);
}
fn hashu(v: u32) u32 {
return @intCast((v *% prime4) >> consts.lookup.shift);
}
test "flate.Lookup add/prev" {
const data = [_]u8{
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
0x01, 0x02, 0x03,
};
var h: Self = .{};
for (data, 0..) |_, i| {
const p = h.add(data[i..], @intCast(i));
if (i >= 8 and i < 24) {
try expect(p == i - 8);
} else {
try expect(p == 0);
}
}
const v = Self.hash(data[2 .. 2 + 4]);
try expect(h.head[v] == 2 + 16);
try expect(h.chain[2 + 16] == 2 + 8);
try expect(h.chain[2 + 8] == 2);
}
test "flate.Lookup bulkAdd" {
const data = "Lorem ipsum dolor sit amet, consectetur adipiscing elit.";
// one by one
var h: Self = .{};
for (data, 0..) |_, i| {
_ = h.add(data[i..], @intCast(i));
}
// in bulk
var bh: Self = .{};
bh.bulkAdd(data, data.len, 0);
try testing.expectEqualSlices(u16, &h.head, &bh.head);
try testing.expectEqualSlices(u16, &h.chain, &bh.chain);
}

160
lib/std/compress/flate/SlidingWindow.zig Normal file
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//! Used in deflate (compression), holds uncompressed data form which Tokens are
//! produces. In combination with Lookup it is used to find matches in history data.
//!
const std = @import("std");
const consts = @import("consts.zig");
const expect = testing.expect;
const assert = std.debug.assert;
const testing = std.testing;
const hist_len = consts.history.len;
const buffer_len = 2 * hist_len;
const min_lookahead = consts.match.min_length + consts.match.max_length;
const max_rp = buffer_len - min_lookahead;
const Self = @This();
buffer: [buffer_len]u8 = undefined,
wp: usize = 0, // write position
rp: usize = 0, // read position
fp: isize = 0, // last flush position, tokens are build from fp..rp
/// Returns number of bytes written, or 0 if buffer is full and need to slide.
pub fn write(self: *Self, buf: []const u8) usize {
if (self.rp >= max_rp) return 0; // need to slide
const n = @min(buf.len, buffer_len - self.wp);
@memcpy(self.buffer[self.wp .. self.wp + n], buf[0..n]);
self.wp += n;
return n;
}
/// Slide buffer for hist_len.
/// Drops old history, preserves between hist_len and hist_len - min_lookahead.
/// Returns number of bytes removed.
pub fn slide(self: *Self) u16 {
assert(self.rp >= max_rp and self.wp >= self.rp);
const n = self.wp - hist_len;
@memcpy(self.buffer[0..n], self.buffer[hist_len..self.wp]);
self.rp -= hist_len;
self.wp -= hist_len;
self.fp -= hist_len;
return @intCast(n);
}
/// Data from the current position (read position). Those part of the buffer is
/// not converted to tokens yet.
fn lookahead(self: *Self) []const u8 {
assert(self.wp >= self.rp);
return self.buffer[self.rp..self.wp];
}
/// Returns part of the lookahead buffer. If should_flush is set no lookahead is
/// preserved otherwise preserves enough data for the longest match. Returns
/// null if there is not enough data.
pub fn activeLookahead(self: *Self, should_flush: bool) ?[]const u8 {
const min: usize = if (should_flush) 0 else min_lookahead;
const lh = self.lookahead();
return if (lh.len > min) lh else null;
}
/// Advances read position, shrinks lookahead.
pub fn advance(self: *Self, n: u16) void {
assert(self.wp >= self.rp + n);
self.rp += n;
}
/// Returns writable part of the buffer, where new uncompressed data can be
/// written.
pub fn writable(self: *Self) []u8 {
return self.buffer[self.wp..];
}
/// Notification of what part of writable buffer is filled with data.
pub fn written(self: *Self, n: usize) void {
self.wp += n;
}
/// Finds match length between previous and current position.
/// Used in hot path!
pub fn match(self: *Self, prev_pos: u16, curr_pos: u16, min_len: u16) u16 {
const max_len: usize = @min(self.wp - curr_pos, consts.match.max_length);
// lookahead buffers from previous and current positions
const prev_lh = self.buffer[prev_pos..][0..max_len];
const curr_lh = self.buffer[curr_pos..][0..max_len];
// If we alread have match (min_len > 0),
// test the first byte above previous len a[min_len] != b[min_len]
// and then all the bytes from that position to zero.
// That is likely positions to find difference than looping from first bytes.
var i: usize = min_len;
if (i > 0) {
if (max_len <= i) return 0;
while (true) {
if (prev_lh[i] != curr_lh[i]) return 0;
if (i == 0) break;
i -= 1;
}
i = min_len;
}
while (i < max_len) : (i += 1)
if (prev_lh[i] != curr_lh[i]) break;
return if (i >= consts.match.min_length) @intCast(i) else 0;
}
/// Current position of non-compressed data. Data before rp are already converted
/// to tokens.
pub fn pos(self: *Self) u16 {
return @intCast(self.rp);
}
/// Notification that token list is cleared.
pub fn flush(self: *Self) void {
self.fp = @intCast(self.rp);
}
/// Part of the buffer since last flush or null if there was slide in between (so
/// fp becomes negative).
pub fn tokensBuffer(self: *Self) ?[]const u8 {
assert(self.fp <= self.rp);
if (self.fp < 0) return null;
return self.buffer[@intCast(self.fp)..self.rp];
}
test "flate.SlidingWindow match" {
const data = "Blah blah blah blah blah!";
var win: Self = .{};
try expect(win.write(data) == data.len);
try expect(win.wp == data.len);
try expect(win.rp == 0);
// length between l symbols
try expect(win.match(1, 6, 0) == 18);
try expect(win.match(1, 11, 0) == 13);
try expect(win.match(1, 16, 0) == 8);
try expect(win.match(1, 21, 0) == 0);
// position 15 = "blah blah!"
// position 20 = "blah!"
try expect(win.match(15, 20, 0) == 4);
try expect(win.match(15, 20, 3) == 4);
try expect(win.match(15, 20, 4) == 0);
}
test "flate.SlidingWindow slide" {
var win: Self = .{};
win.wp = Self.buffer_len - 11;
win.rp = Self.buffer_len - 111;
win.buffer[win.rp] = 0xab;
try expect(win.lookahead().len == 100);
try expect(win.tokensBuffer().?.len == win.rp);
const n = win.slide();
try expect(n == 32757);
try expect(win.buffer[win.rp] == 0xab);
try expect(win.rp == Self.hist_len - 111);
try expect(win.wp == Self.hist_len - 11);
try expect(win.lookahead().len == 100);
try expect(win.tokensBuffer() == null);
}

327
lib/std/compress/flate/Token.zig Normal file
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//! Token cat be literal: single byte of data or match; reference to the slice of
//! data in the same stream represented with <length, distance>. Where length
//! can be 3 - 258 bytes, and distance 1 - 32768 bytes.
//!
const std = @import("std");
const assert = std.debug.assert;
const print = std.debug.print;
const expect = std.testing.expect;
const consts = @import("consts.zig").match;
const Token = @This();
pub const Kind = enum(u1) {
literal,
match,
};
// Distance range 1 - 32768, stored in dist as 0 - 32767 (fits u15)
dist: u15 = 0,
// Length range 3 - 258, stored in len_lit as 0 - 255 (fits u8)
len_lit: u8 = 0,
kind: Kind = .literal,
pub fn literal(t: Token) u8 {
return t.len_lit;
}
pub fn distance(t: Token) u16 {
return @as(u16, t.dist) + consts.min_distance;
}
pub fn length(t: Token) u16 {
return @as(u16, t.len_lit) + consts.base_length;
}
pub fn initLiteral(lit: u8) Token {
return .{ .kind = .literal, .len_lit = lit };
}
// distance range 1 - 32768, stored in dist as 0 - 32767 (u15)
// length range 3 - 258, stored in len_lit as 0 - 255 (u8)
pub fn initMatch(dist: u16, len: u16) Token {
assert(len >= consts.min_length and len <= consts.max_length);
assert(dist >= consts.min_distance and dist <= consts.max_distance);
return .{
.kind = .match,
.dist = @intCast(dist - consts.min_distance),
.len_lit = @intCast(len - consts.base_length),
};
}
pub fn eql(t: Token, o: Token) bool {
return t.kind == o.kind and
t.dist == o.dist and
t.len_lit == o.len_lit;
}
pub fn lengthCode(t: Token) u16 {
return match_lengths[match_lengths_index[t.len_lit]].code;
}
pub fn lengthEncoding(t: Token) MatchLength {
var c = match_lengths[match_lengths_index[t.len_lit]];
c.extra_length = t.len_lit - c.base_scaled;
return c;
}
// Returns the distance code corresponding to a specific distance.
// Distance code is in range: 0 - 29.
pub fn distanceCode(t: Token) u8 {
var dist: u16 = t.dist;
if (dist < match_distances_index.len) {
return match_distances_index[dist];
}
dist >>= 7;
if (dist < match_distances_index.len) {
return match_distances_index[dist] + 14;
}
dist >>= 7;
return match_distances_index[dist] + 28;
}
pub fn distanceEncoding(t: Token) MatchDistance {
var c = match_distances[t.distanceCode()];
c.extra_distance = t.dist - c.base_scaled;
return c;
}
pub fn lengthExtraBits(code: u32) u8 {
return match_lengths[code - length_codes_start].extra_bits;
}
pub fn matchLength(code: u8) MatchLength {
return match_lengths[code];
}
pub fn matchDistance(code: u8) MatchDistance {
return match_distances[code];
}
pub fn distanceExtraBits(code: u32) u8 {
return match_distances[code].extra_bits;
}
pub fn show(t: Token) void {
if (t.kind == .literal) {
print("L('{c}'), ", .{t.literal()});
} else {
print("M({d}, {d}), ", .{ t.distance(), t.length() });
}
}
// Retruns index in match_lengths table for each length in range 0-255.
const match_lengths_index = [_]u8{
0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
13, 13, 13, 13, 14, 14, 14, 14, 15, 15,
15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
19, 19, 19, 19, 20, 20, 20, 20, 20, 20,
20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
27, 27, 27, 27, 27, 28,
};
const MatchLength = struct {
code: u16,
base_scaled: u8, // base - 3, scaled to fit into u8 (0-255), same as lit_len field in Token.
base: u16, // 3-258
extra_length: u8 = 0,
extra_bits: u4,
};
// match_lengths represents table from rfc (https://datatracker.ietf.org/doc/html/rfc1951#page-12)
//
// Extra Extra Extra
// Code Bits Length(s) Code Bits Lengths Code Bits Length(s)
// ---- ---- ------ ---- ---- ------- ---- ---- -------
// 257 0 3 267 1 15,16 277 4 67-82
// 258 0 4 268 1 17,18 278 4 83-98
// 259 0 5 269 2 19-22 279 4 99-114
// 260 0 6 270 2 23-26 280 4 115-130
// 261 0 7 271 2 27-30 281 5 131-162
// 262 0 8 272 2 31-34 282 5 163-194
// 263 0 9 273 3 35-42 283 5 195-226
// 264 0 10 274 3 43-50 284 5 227-257
// 265 1 11,12 275 3 51-58 285 0 258
// 266 1 13,14 276 3 59-66
//
pub const length_codes_start = 257;
const match_lengths = [_]MatchLength{
.{ .extra_bits = 0, .base_scaled = 0, .base = 3, .code = 257 },
.{ .extra_bits = 0, .base_scaled = 1, .base = 4, .code = 258 },
.{ .extra_bits = 0, .base_scaled = 2, .base = 5, .code = 259 },
.{ .extra_bits = 0, .base_scaled = 3, .base = 6, .code = 260 },
.{ .extra_bits = 0, .base_scaled = 4, .base = 7, .code = 261 },
.{ .extra_bits = 0, .base_scaled = 5, .base = 8, .code = 262 },
.{ .extra_bits = 0, .base_scaled = 6, .base = 9, .code = 263 },
.{ .extra_bits = 0, .base_scaled = 7, .base = 10, .code = 264 },
.{ .extra_bits = 1, .base_scaled = 8, .base = 11, .code = 265 },
.{ .extra_bits = 1, .base_scaled = 10, .base = 13, .code = 266 },
.{ .extra_bits = 1, .base_scaled = 12, .base = 15, .code = 267 },
.{ .extra_bits = 1, .base_scaled = 14, .base = 17, .code = 268 },
.{ .extra_bits = 2, .base_scaled = 16, .base = 19, .code = 269 },
.{ .extra_bits = 2, .base_scaled = 20, .base = 23, .code = 270 },
.{ .extra_bits = 2, .base_scaled = 24, .base = 27, .code = 271 },
.{ .extra_bits = 2, .base_scaled = 28, .base = 31, .code = 272 },
.{ .extra_bits = 3, .base_scaled = 32, .base = 35, .code = 273 },
.{ .extra_bits = 3, .base_scaled = 40, .base = 43, .code = 274 },
.{ .extra_bits = 3, .base_scaled = 48, .base = 51, .code = 275 },
.{ .extra_bits = 3, .base_scaled = 56, .base = 59, .code = 276 },
.{ .extra_bits = 4, .base_scaled = 64, .base = 67, .code = 277 },
.{ .extra_bits = 4, .base_scaled = 80, .base = 83, .code = 278 },
.{ .extra_bits = 4, .base_scaled = 96, .base = 99, .code = 279 },
.{ .extra_bits = 4, .base_scaled = 112, .base = 115, .code = 280 },
.{ .extra_bits = 5, .base_scaled = 128, .base = 131, .code = 281 },
.{ .extra_bits = 5, .base_scaled = 160, .base = 163, .code = 282 },
.{ .extra_bits = 5, .base_scaled = 192, .base = 195, .code = 283 },
.{ .extra_bits = 5, .base_scaled = 224, .base = 227, .code = 284 },
.{ .extra_bits = 0, .base_scaled = 255, .base = 258, .code = 285 },
};
// Used in distanceCode fn to get index in match_distance table for each distance in range 0-32767.
const match_distances_index = [_]u8{
0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
};
const MatchDistance = struct {
base_scaled: u16, // base - 1, same as Token dist field
base: u16,
extra_distance: u16 = 0,
code: u8,
extra_bits: u4,
};
// match_distances represents table from rfc (https://datatracker.ietf.org/doc/html/rfc1951#page-12)
//
// Extra Extra Extra
// Code Bits Dist Code Bits Dist Code Bits Distance
// ---- ---- ---- ---- ---- ------ ---- ---- --------
// 0 0 1 10 4 33-48 20 9 1025-1536
// 1 0 2 11 4 49-64 21 9 1537-2048
// 2 0 3 12 5 65-96 22 10 2049-3072
// 3 0 4 13 5 97-128 23 10 3073-4096
// 4 1 5,6 14 6 129-192 24 11 4097-6144
// 5 1 7,8 15 6 193-256 25 11 6145-8192
// 6 2 9-12 16 7 257-384 26 12 8193-12288
// 7 2 13-16 17 7 385-512 27 12 12289-16384
// 8 3 17-24 18 8 513-768 28 13 16385-24576
// 9 3 25-32 19 8 769-1024 29 13 24577-32768
//
const match_distances = [_]MatchDistance{
.{ .extra_bits = 0, .base_scaled = 0x0000, .code = 0, .base = 1 },
.{ .extra_bits = 0, .base_scaled = 0x0001, .code = 1, .base = 2 },
.{ .extra_bits = 0, .base_scaled = 0x0002, .code = 2, .base = 3 },
.{ .extra_bits = 0, .base_scaled = 0x0003, .code = 3, .base = 4 },
.{ .extra_bits = 1, .base_scaled = 0x0004, .code = 4, .base = 5 },
.{ .extra_bits = 1, .base_scaled = 0x0006, .code = 5, .base = 7 },
.{ .extra_bits = 2, .base_scaled = 0x0008, .code = 6, .base = 9 },
.{ .extra_bits = 2, .base_scaled = 0x000c, .code = 7, .base = 13 },
.{ .extra_bits = 3, .base_scaled = 0x0010, .code = 8, .base = 17 },
.{ .extra_bits = 3, .base_scaled = 0x0018, .code = 9, .base = 25 },
.{ .extra_bits = 4, .base_scaled = 0x0020, .code = 10, .base = 33 },
.{ .extra_bits = 4, .base_scaled = 0x0030, .code = 11, .base = 49 },
.{ .extra_bits = 5, .base_scaled = 0x0040, .code = 12, .base = 65 },
.{ .extra_bits = 5, .base_scaled = 0x0060, .code = 13, .base = 97 },
.{ .extra_bits = 6, .base_scaled = 0x0080, .code = 14, .base = 129 },
.{ .extra_bits = 6, .base_scaled = 0x00c0, .code = 15, .base = 193 },
.{ .extra_bits = 7, .base_scaled = 0x0100, .code = 16, .base = 257 },
.{ .extra_bits = 7, .base_scaled = 0x0180, .code = 17, .base = 385 },
.{ .extra_bits = 8, .base_scaled = 0x0200, .code = 18, .base = 513 },
.{ .extra_bits = 8, .base_scaled = 0x0300, .code = 19, .base = 769 },
.{ .extra_bits = 9, .base_scaled = 0x0400, .code = 20, .base = 1025 },
.{ .extra_bits = 9, .base_scaled = 0x0600, .code = 21, .base = 1537 },
.{ .extra_bits = 10, .base_scaled = 0x0800, .code = 22, .base = 2049 },
.{ .extra_bits = 10, .base_scaled = 0x0c00, .code = 23, .base = 3073 },
.{ .extra_bits = 11, .base_scaled = 0x1000, .code = 24, .base = 4097 },
.{ .extra_bits = 11, .base_scaled = 0x1800, .code = 25, .base = 6145 },
.{ .extra_bits = 12, .base_scaled = 0x2000, .code = 26, .base = 8193 },
.{ .extra_bits = 12, .base_scaled = 0x3000, .code = 27, .base = 12289 },
.{ .extra_bits = 13, .base_scaled = 0x4000, .code = 28, .base = 16385 },
.{ .extra_bits = 13, .base_scaled = 0x6000, .code = 29, .base = 24577 },
};
test "flate.Token size" {
try expect(@sizeOf(Token) == 4);
}
// testing table https://datatracker.ietf.org/doc/html/rfc1951#page-12
test "flate.Token MatchLength" {
var c = Token.initMatch(1, 4).lengthEncoding();
try expect(c.code == 258);
try expect(c.extra_bits == 0);
try expect(c.extra_length == 0);
c = Token.initMatch(1, 11).lengthEncoding();
try expect(c.code == 265);
try expect(c.extra_bits == 1);
try expect(c.extra_length == 0);
c = Token.initMatch(1, 12).lengthEncoding();
try expect(c.code == 265);
try expect(c.extra_bits == 1);
try expect(c.extra_length == 1);
c = Token.initMatch(1, 130).lengthEncoding();
try expect(c.code == 280);
try expect(c.extra_bits == 4);
try expect(c.extra_length == 130 - 115);
}
test "flate.Token MatchDistance" {
var c = Token.initMatch(1, 4).distanceEncoding();
try expect(c.code == 0);
try expect(c.extra_bits == 0);
try expect(c.extra_distance == 0);
c = Token.initMatch(192, 4).distanceEncoding();
try expect(c.code == 14);
try expect(c.extra_bits == 6);
try expect(c.extra_distance == 192 - 129);
}
test "flate.Token match_lengths" {
for (match_lengths, 0..) |ml, i| {
try expect(@as(u16, ml.base_scaled) + 3 == ml.base);
try expect(i + 257 == ml.code);
}
for (match_distances, 0..) |mo, i| {
try expect(mo.base_scaled + 1 == mo.base);
try expect(i == mo.code);
}
}

333
lib/std/compress/flate/bit_reader.zig Normal file
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@@ -0,0 +1,333 @@
const std = @import("std");
const assert = std.debug.assert;
const testing = std.testing;
pub fn bitReader(reader: anytype) BitReader(@TypeOf(reader)) {
return BitReader(@TypeOf(reader)).init(reader);
}
/// Bit reader used during inflate (decompression). Has internal buffer of 64
/// bits which shifts right after bits are consumed. Uses forward_reader to fill
/// that internal buffer when needed.
///
/// readF is the core function. Supports few different ways of getting bits
/// controlled by flags. In hot path we try to avoid checking whether we need to
/// fill buffer from forward_reader by calling fill in advance and readF with
/// buffered flag set.
///
pub fn BitReader(comptime ReaderType: type) type {
return struct {
// Underlying reader used for filling internal bits buffer
forward_reader: ReaderType = undefined,
// Internal buffer of 64 bits
bits: u64 = 0,
// Number of bits in the buffer
nbits: u32 = 0,
const Self = @This();
pub const Error = ReaderType.Error || error{EndOfStream};
pub fn init(rdr: ReaderType) Self {
var self = Self{ .forward_reader = rdr };
self.fill(1) catch {};
return self;
}
/// Try to have `nice` bits are available in buffer. Reads from
/// forward reader if there is no `nice` bits in buffer. Returns error
/// if end of forward stream is reached and internal buffer is empty.
/// It will not error if less than `nice` bits are in buffer, only when
/// all bits are exhausted. During inflate we usually know what is the
/// maximum bits for the next step but usually that step will need less
/// bits to decode. So `nice` is not hard limit, it will just try to have
/// that number of bits available. If end of forward stream is reached
/// it may be some extra zero bits in buffer.
pub inline fn fill(self: *Self, nice: u6) !void {
if (self.nbits >= nice) {
return; // We have enought bits
}
// Read more bits from forward reader
// Number of empty bytes in bits, round nbits to whole bytes.
const empty_bytes =
@as(u8, if (self.nbits & 0x7 == 0) 8 else 7) - // 8 for 8, 16, 24..., 7 otherwise
(self.nbits >> 3); // 0 for 0-7, 1 for 8-16, ... same as / 8
var buf: [8]u8 = [_]u8{0} ** 8;
const bytes_read = self.forward_reader.readAll(buf[0..empty_bytes]) catch 0;
if (bytes_read > 0) {
const u: u64 = std.mem.readInt(u64, buf[0..8], .little);
self.bits |= u << @as(u6, @intCast(self.nbits));
self.nbits += 8 * @as(u8, @intCast(bytes_read));
return;
}
if (self.nbits == 0)
return error.EndOfStream;
}
/// Read exactly buf.len bytes into buf.
pub fn readAll(self: *Self, buf: []u8) !void {
assert(self.alignBits() == 0); // internal bits must be at byte boundary
// First read from internal bits buffer.
var n: usize = 0;
while (self.nbits > 0 and n < buf.len) {
buf[n] = try self.readF(u8, flag.buffered);
n += 1;
}
// Then use forward reader for all other bytes.
try self.forward_reader.readNoEof(buf[n..]);
}
pub const flag = struct {
pub const peek: u3 = 0b001; // dont advance internal buffer, just get bits, leave them in buffer
pub const buffered: u3 = 0b010; // assume that there is no need to fill, fill should be called before
pub const reverse: u3 = 0b100; // bit reverse readed bits
};
/// Alias for readF(U, 0).
pub fn read(self: *Self, comptime U: type) !U {
return self.readF(U, 0);
}
/// Alias for readF with flag.peak set.
pub inline fn peekF(self: *Self, comptime U: type, comptime how: u3) !U {
return self.readF(U, how | flag.peek);
}
/// Read with flags provided.
pub fn readF(self: *Self, comptime U: type, comptime how: u3) !U {
const n: u6 = @bitSizeOf(U);
switch (how) {
0 => { // `normal` read
try self.fill(n); // ensure that there are n bits in the buffer
const u: U = @truncate(self.bits); // get n bits
try self.shift(n); // advance buffer for n
return u;
},
(flag.peek) => { // no shift, leave bits in the buffer
try self.fill(n);
return @truncate(self.bits);
},
flag.buffered => { // no fill, assume that buffer has enought bits
const u: U = @truncate(self.bits);
try self.shift(n);
return u;
},
(flag.reverse) => { // same as 0 with bit reverse
try self.fill(n);
const u: U = @truncate(self.bits);
try self.shift(n);
return @bitReverse(u);
},
(flag.peek | flag.reverse) => {
try self.fill(n);
return @bitReverse(@as(U, @truncate(self.bits)));
},
(flag.buffered | flag.reverse) => {
const u: U = @truncate(self.bits);
try self.shift(n);
return @bitReverse(u);
},
(flag.peek | flag.buffered) => {
return @truncate(self.bits);
},
(flag.peek | flag.buffered | flag.reverse) => {
return @bitReverse(@as(U, @truncate(self.bits)));
},
}
}
/// Read n number of bits.
/// Only buffered flag can be used in how.
pub fn readN(self: *Self, n: u4, comptime how: u3) !u16 {
switch (how) {
0 => {
try self.fill(n);
},
flag.buffered => {},
else => unreachable,
}
const mask: u16 = (@as(u16, 1) << n) - 1;
const u: u16 = @as(u16, @truncate(self.bits)) & mask;
try self.shift(n);
return u;
}
/// Advance buffer for n bits.
pub fn shift(self: *Self, n: u6) !void {
if (n > self.nbits) return error.EndOfStream;
self.bits >>= n;
self.nbits -= n;
}
/// Skip n bytes.
pub fn skipBytes(self: *Self, n: u16) !void {
for (0..n) |_| {
try self.fill(8);
try self.shift(8);
}
}
// Number of bits to align stream to the byte boundary.
fn alignBits(self: *Self) u3 {
return @intCast(self.nbits & 0x7);
}
/// Align stream to the byte boundary.
pub fn alignToByte(self: *Self) void {
const ab = self.alignBits();
if (ab > 0) self.shift(ab) catch unreachable;
}
/// Skip zero terminated string.
pub fn skipStringZ(self: *Self) !void {
while (true) {
if (try self.readF(u8, 0) == 0) break;
}
}
/// Read deflate fixed fixed code.
/// Reads first 7 bits, and then mybe 1 or 2 more to get full 7,8 or 9 bit code.
/// ref: https://datatracker.ietf.org/doc/html/rfc1951#page-12
/// Lit Value Bits Codes
/// --------- ---- -----
/// 0 - 143 8 00110000 through
/// 10111111
/// 144 - 255 9 110010000 through
/// 111111111
/// 256 - 279 7 0000000 through
/// 0010111
/// 280 - 287 8 11000000 through
/// 11000111
pub fn readFixedCode(self: *Self) !u16 {
try self.fill(7 + 2);
const code7 = try self.readF(u7, flag.buffered | flag.reverse);
if (code7 <= 0b0010_111) { // 7 bits, 256-279, codes 0000_000 - 0010_111
return @as(u16, code7) + 256;
} else if (code7 <= 0b1011_111) { // 8 bits, 0-143, codes 0011_0000 through 1011_1111
return (@as(u16, code7) << 1) + @as(u16, try self.readF(u1, flag.buffered)) - 0b0011_0000;
} else if (code7 <= 0b1100_011) { // 8 bit, 280-287, codes 1100_0000 - 1100_0111
return (@as(u16, code7 - 0b1100000) << 1) + try self.readF(u1, flag.buffered) + 280;
} else { // 9 bit, 144-255, codes 1_1001_0000 - 1_1111_1111
return (@as(u16, code7 - 0b1100_100) << 2) + @as(u16, try self.readF(u2, flag.buffered | flag.reverse)) + 144;
}
}
};
}
test "flate.BitReader" {
var fbs = std.io.fixedBufferStream(&[_]u8{ 0xf3, 0x48, 0xcd, 0xc9, 0x00, 0x00 });
var br = bitReader(fbs.reader());
const F = BitReader(@TypeOf(fbs.reader())).flag;
try testing.expectEqual(@as(u8, 48), br.nbits);
try testing.expectEqual(@as(u64, 0xc9cd48f3), br.bits);
try testing.expect(try br.readF(u1, 0) == 0b0000_0001);
try testing.expect(try br.readF(u2, 0) == 0b0000_0001);
try testing.expectEqual(@as(u8, 48 - 3), br.nbits);
try testing.expectEqual(@as(u3, 5), br.alignBits());
try testing.expect(try br.readF(u8, F.peek) == 0b0001_1110);
try testing.expect(try br.readF(u9, F.peek) == 0b1_0001_1110);
try br.shift(9);
try testing.expectEqual(@as(u8, 36), br.nbits);
try testing.expectEqual(@as(u3, 4), br.alignBits());
try testing.expect(try br.readF(u4, 0) == 0b0100);
try testing.expectEqual(@as(u8, 32), br.nbits);
try testing.expectEqual(@as(u3, 0), br.alignBits());
try br.shift(1);
try testing.expectEqual(@as(u3, 7), br.alignBits());
try br.shift(1);
try testing.expectEqual(@as(u3, 6), br.alignBits());
br.alignToByte();
try testing.expectEqual(@as(u3, 0), br.alignBits());
try testing.expectEqual(@as(u64, 0xc9), br.bits);
try testing.expectEqual(@as(u16, 0x9), try br.readN(4, 0));
try testing.expectEqual(@as(u16, 0xc), try br.readN(4, 0));
}
test "flate.BitReader read block type 1 data" {
const data = [_]u8{
0xf3, 0x48, 0xcd, 0xc9, 0xc9, 0x57, 0x28, 0xcf, // deflate data block type 1
0x2f, 0xca, 0x49, 0xe1, 0x02, 0x00,
0x0c, 0x01, 0x02, 0x03, //
0xaa, 0xbb, 0xcc, 0xdd,
};
var fbs = std.io.fixedBufferStream(&data);
var br = bitReader(fbs.reader());
const F = BitReader(@TypeOf(fbs.reader())).flag;
try testing.expectEqual(@as(u1, 1), try br.readF(u1, 0)); // bfinal
try testing.expectEqual(@as(u2, 1), try br.readF(u2, 0)); // block_type
for ("Hello world\n") |c| {
try testing.expectEqual(@as(u8, c), try br.readF(u8, F.reverse) - 0x30);
}
try testing.expectEqual(@as(u7, 0), try br.readF(u7, 0)); // end of block
br.alignToByte();
try testing.expectEqual(@as(u32, 0x0302010c), try br.readF(u32, 0));
try testing.expectEqual(@as(u16, 0xbbaa), try br.readF(u16, 0));
try testing.expectEqual(@as(u16, 0xddcc), try br.readF(u16, 0));
}
test "flate.BitReader init" {
const data = [_]u8{
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
};
var fbs = std.io.fixedBufferStream(&data);
var br = bitReader(fbs.reader());
try testing.expectEqual(@as(u64, 0x08_07_06_05_04_03_02_01), br.bits);
try br.shift(8);
try testing.expectEqual(@as(u64, 0x00_08_07_06_05_04_03_02), br.bits);
try br.fill(60); // fill with 1 byte
try testing.expectEqual(@as(u64, 0x01_08_07_06_05_04_03_02), br.bits);
try br.shift(8 * 4 + 4);
try testing.expectEqual(@as(u64, 0x00_00_00_00_00_10_80_70), br.bits);
try br.fill(60); // fill with 4 bytes (shift by 4)
try testing.expectEqual(@as(u64, 0x00_50_40_30_20_10_80_70), br.bits);
try testing.expectEqual(@as(u8, 8 * 7 + 4), br.nbits);
try br.shift(@intCast(br.nbits)); // clear buffer
try br.fill(8); // refill with the rest of the bytes
try testing.expectEqual(@as(u64, 0x00_00_00_00_00_08_07_06), br.bits);
}
test "flate.BitReader readAll" {
const data = [_]u8{
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
};
var fbs = std.io.fixedBufferStream(&data);
var br = bitReader(fbs.reader());
try testing.expectEqual(@as(u64, 0x08_07_06_05_04_03_02_01), br.bits);
var out: [16]u8 = undefined;
try br.readAll(out[0..]);
try testing.expect(br.nbits == 0);
try testing.expect(br.bits == 0);
try testing.expectEqualSlices(u8, data[0..16], &out);
}
test "flate.BitReader readFixedCode" {
const fixed_codes = @import("huffman_encoder.zig").fixed_codes;
var fbs = std.io.fixedBufferStream(&fixed_codes);
var rdr = bitReader(fbs.reader());
for (0..286) |c| {
try testing.expectEqual(c, try rdr.readFixedCode());
}
try testing.expect(rdr.nbits == 0);
}

99
lib/std/compress/flate/bit_writer.zig Normal file
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const std = @import("std");
const assert = std.debug.assert;
/// Bit writer for use in deflate (compression).
///
/// Has internal bits buffer of 64 bits and internal bytes buffer of 248 bytes.
/// When we accumulate 48 bits 6 bytes are moved to the bytes buffer. When we
/// accumulate 240 bytes they are flushed to the underlying inner_writer.
///
pub fn BitWriter(comptime WriterType: type) type {
// buffer_flush_size indicates the buffer size
// after which bytes are flushed to the writer.
// Should preferably be a multiple of 6, since
// we accumulate 6 bytes between writes to the buffer.
const buffer_flush_size = 240;
// buffer_size is the actual output byte buffer size.
// It must have additional headroom for a flush
// which can contain up to 8 bytes.
const buffer_size = buffer_flush_size + 8;
return struct {
inner_writer: WriterType,
// Data waiting to be written is bytes[0 .. nbytes]
// and then the low nbits of bits. Data is always written
// sequentially into the bytes array.
bits: u64 = 0,
nbits: u32 = 0, // number of bits
bytes: [buffer_size]u8 = undefined,
nbytes: u32 = 0, // number of bytes
const Self = @This();
pub const Error = WriterType.Error || error{UnfinishedBits};
pub fn init(writer: WriterType) Self {
return .{ .inner_writer = writer };
}
pub fn setWriter(self: *Self, new_writer: WriterType) void {
//assert(self.bits == 0 and self.nbits == 0 and self.nbytes == 0);
self.inner_writer = new_writer;
}
pub fn flush(self: *Self) Error!void {
var n = self.nbytes;
while (self.nbits != 0) {
self.bytes[n] = @as(u8, @truncate(self.bits));
self.bits >>= 8;
if (self.nbits > 8) { // Avoid underflow
self.nbits -= 8;
} else {
self.nbits = 0;
}
n += 1;
}
self.bits = 0;
_ = try self.inner_writer.write(self.bytes[0..n]);
self.nbytes = 0;
}
pub fn writeBits(self: *Self, b: u32, nb: u32) Error!void {
self.bits |= @as(u64, @intCast(b)) << @as(u6, @intCast(self.nbits));
self.nbits += nb;
if (self.nbits < 48)
return;
var n = self.nbytes;
std.mem.writeInt(u64, self.bytes[n..][0..8], self.bits, .little);
n += 6;
if (n >= buffer_flush_size) {
_ = try self.inner_writer.write(self.bytes[0..n]);
n = 0;
}
self.nbytes = n;
self.bits >>= 48;
self.nbits -= 48;
}
pub fn writeBytes(self: *Self, bytes: []const u8) Error!void {
var n = self.nbytes;
if (self.nbits & 7 != 0) {
return error.UnfinishedBits;
}
while (self.nbits != 0) {
self.bytes[n] = @as(u8, @truncate(self.bits));
self.bits >>= 8;
self.nbits -= 8;
n += 1;
}
if (n != 0) {
_ = try self.inner_writer.write(self.bytes[0..n]);
}
self.nbytes = 0;
_ = try self.inner_writer.write(bytes);
}
};
}

706
lib/std/compress/flate/block_writer.zig Normal file
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const std = @import("std");
const io = std.io;
const assert = std.debug.assert;
const hc = @import("huffman_encoder.zig");
const consts = @import("consts.zig").huffman;
const Token = @import("Token.zig");
const BitWriter = @import("bit_writer.zig").BitWriter;
pub fn blockWriter(writer: anytype) BlockWriter(@TypeOf(writer)) {
return BlockWriter(@TypeOf(writer)).init(writer);
}
/// Accepts list of tokens, decides what is best block type to write. What block
/// type will provide best compression. Writes header and body of the block.
///
pub fn BlockWriter(comptime WriterType: type) type {
const BitWriterType = BitWriter(WriterType);
return struct {
const codegen_order = consts.codegen_order;
const end_code_mark = 255;
const Self = @This();
pub const Error = BitWriterType.Error;
bit_writer: BitWriterType,
codegen_freq: [consts.codegen_code_count]u16 = undefined,
literal_freq: [consts.max_num_lit]u16 = undefined,
distance_freq: [consts.distance_code_count]u16 = undefined,
codegen: [consts.max_num_lit + consts.distance_code_count + 1]u8 = undefined,
literal_encoding: hc.LiteralEncoder = .{},
distance_encoding: hc.DistanceEncoder = .{},
codegen_encoding: hc.CodegenEncoder = .{},
fixed_literal_encoding: hc.LiteralEncoder,
fixed_distance_encoding: hc.DistanceEncoder,
huff_distance: hc.DistanceEncoder,
pub fn init(writer: WriterType) Self {
return .{
.bit_writer = BitWriterType.init(writer),
.fixed_literal_encoding = hc.fixedLiteralEncoder(),
.fixed_distance_encoding = hc.fixedDistanceEncoder(),
.huff_distance = hc.huffmanDistanceEncoder(),
};
}
/// Flush intrenal bit buffer to the writer.
/// Should be called only when bit stream is at byte boundary.
///
/// That is after final block; when last byte could be incomplete or
/// after stored block; which is aligned to the byte bounday (it has x
/// padding bits after first 3 bits).
pub fn flush(self: *Self) Error!void {
try self.bit_writer.flush();
}
pub fn setWriter(self: *Self, new_writer: WriterType) void {
self.bit_writer.setWriter(new_writer);
}
fn writeCode(self: *Self, c: hc.HuffCode) Error!void {
try self.bit_writer.writeBits(c.code, c.len);
}
// RFC 1951 3.2.7 specifies a special run-length encoding for specifying
// the literal and distance lengths arrays (which are concatenated into a single
// array). This method generates that run-length encoding.
//
// The result is written into the codegen array, and the frequencies
// of each code is written into the codegen_freq array.
// Codes 0-15 are single byte codes. Codes 16-18 are followed by additional
// information. Code bad_code is an end marker
//
// num_literals: The number of literals in literal_encoding
// num_distances: The number of distances in distance_encoding
// lit_enc: The literal encoder to use
// dist_enc: The distance encoder to use
fn generateCodegen(
self: *Self,
num_literals: u32,
num_distances: u32,
lit_enc: *hc.LiteralEncoder,
dist_enc: *hc.DistanceEncoder,
) void {
for (self.codegen_freq, 0..) |_, i| {
self.codegen_freq[i] = 0;
}
// Note that we are using codegen both as a temporary variable for holding
// a copy of the frequencies, and as the place where we put the result.
// This is fine because the output is always shorter than the input used
// so far.
var codegen = &self.codegen; // cache
// Copy the concatenated code sizes to codegen. Put a marker at the end.
var cgnl = codegen[0..num_literals];
for (cgnl, 0..) |_, i| {
cgnl[i] = @as(u8, @intCast(lit_enc.codes[i].len));
}
cgnl = codegen[num_literals .. num_literals + num_distances];
for (cgnl, 0..) |_, i| {
cgnl[i] = @as(u8, @intCast(dist_enc.codes[i].len));
}
codegen[num_literals + num_distances] = end_code_mark;
var size = codegen[0];
var count: i32 = 1;
var out_index: u32 = 0;
var in_index: u32 = 1;
while (size != end_code_mark) : (in_index += 1) {
// INVARIANT: We have seen "count" copies of size that have not yet
// had output generated for them.
const next_size = codegen[in_index];
if (next_size == size) {
count += 1;
continue;
}
// We need to generate codegen indicating "count" of size.
if (size != 0) {
codegen[out_index] = size;
out_index += 1;
self.codegen_freq[size] += 1;
count -= 1;
while (count >= 3) {
var n: i32 = 6;
if (n > count) {
n = count;
}
codegen[out_index] = 16;
out_index += 1;
codegen[out_index] = @as(u8, @intCast(n - 3));
out_index += 1;
self.codegen_freq[16] += 1;
count -= n;
}
} else {
while (count >= 11) {
var n: i32 = 138;
if (n > count) {
n = count;
}
codegen[out_index] = 18;
out_index += 1;
codegen[out_index] = @as(u8, @intCast(n - 11));
out_index += 1;
self.codegen_freq[18] += 1;
count -= n;
}
if (count >= 3) {
// 3 <= count <= 10
codegen[out_index] = 17;
out_index += 1;
codegen[out_index] = @as(u8, @intCast(count - 3));
out_index += 1;
self.codegen_freq[17] += 1;
count = 0;
}
}
count -= 1;
while (count >= 0) : (count -= 1) {
codegen[out_index] = size;
out_index += 1;
self.codegen_freq[size] += 1;
}
// Set up invariant for next time through the loop.
size = next_size;
count = 1;
}
// Marker indicating the end of the codegen.
codegen[out_index] = end_code_mark;
}
const DynamicSize = struct {
size: u32,
num_codegens: u32,
};
// dynamicSize returns the size of dynamically encoded data in bits.
fn dynamicSize(
self: *Self,
lit_enc: *hc.LiteralEncoder, // literal encoder
dist_enc: *hc.DistanceEncoder, // distance encoder
extra_bits: u32,
) DynamicSize {
var num_codegens = self.codegen_freq.len;
while (num_codegens > 4 and self.codegen_freq[codegen_order[num_codegens - 1]] == 0) {
num_codegens -= 1;
}
const header = 3 + 5 + 5 + 4 + (3 * num_codegens) +
self.codegen_encoding.bitLength(self.codegen_freq[0..]) +
self.codegen_freq[16] * 2 +
self.codegen_freq[17] * 3 +
self.codegen_freq[18] * 7;
const size = header +
lit_enc.bitLength(&self.literal_freq) +
dist_enc.bitLength(&self.distance_freq) +
extra_bits;
return DynamicSize{
.size = @as(u32, @intCast(size)),
.num_codegens = @as(u32, @intCast(num_codegens)),
};
}
// fixedSize returns the size of dynamically encoded data in bits.
fn fixedSize(self: *Self, extra_bits: u32) u32 {
return 3 +
self.fixed_literal_encoding.bitLength(&self.literal_freq) +
self.fixed_distance_encoding.bitLength(&self.distance_freq) +
extra_bits;
}
const StoredSize = struct {
size: u32,
storable: bool,
};
// storedSizeFits calculates the stored size, including header.
// The function returns the size in bits and whether the block
// fits inside a single block.
fn storedSizeFits(in: ?[]const u8) StoredSize {
if (in == null) {
return .{ .size = 0, .storable = false };
}
if (in.?.len <= consts.max_store_block_size) {
return .{ .size = @as(u32, @intCast((in.?.len + 5) * 8)), .storable = true };
}
return .{ .size = 0, .storable = false };
}
// Write the header of a dynamic Huffman block to the output stream.
//
// num_literals: The number of literals specified in codegen
// num_distances: The number of distances specified in codegen
// num_codegens: The number of codegens used in codegen
// eof: Is it the end-of-file? (end of stream)
fn dynamicHeader(
self: *Self,
num_literals: u32,
num_distances: u32,
num_codegens: u32,
eof: bool,
) Error!void {
const first_bits: u32 = if (eof) 5 else 4;
try self.bit_writer.writeBits(first_bits, 3);
try self.bit_writer.writeBits(num_literals - 257, 5);
try self.bit_writer.writeBits(num_distances - 1, 5);
try self.bit_writer.writeBits(num_codegens - 4, 4);
var i: u32 = 0;
while (i < num_codegens) : (i += 1) {
const value = self.codegen_encoding.codes[codegen_order[i]].len;
try self.bit_writer.writeBits(value, 3);
}
i = 0;
while (true) {
const code_word: u32 = @as(u32, @intCast(self.codegen[i]));
i += 1;
if (code_word == end_code_mark) {
break;
}
try self.writeCode(self.codegen_encoding.codes[@as(u32, @intCast(code_word))]);
switch (code_word) {
16 => {
try self.bit_writer.writeBits(self.codegen[i], 2);
i += 1;
},
17 => {
try self.bit_writer.writeBits(self.codegen[i], 3);
i += 1;
},
18 => {
try self.bit_writer.writeBits(self.codegen[i], 7);
i += 1;
},
else => {},
}
}
}
fn storedHeader(self: *Self, length: usize, eof: bool) Error!void {
assert(length <= 65535);
const flag: u32 = if (eof) 1 else 0;
try self.bit_writer.writeBits(flag, 3);
try self.flush();
const l: u16 = @intCast(length);
try self.bit_writer.writeBits(l, 16);
try self.bit_writer.writeBits(~l, 16);
}
fn fixedHeader(self: *Self, eof: bool) Error!void {
// Indicate that we are a fixed Huffman block
var value: u32 = 2;
if (eof) {
value = 3;
}
try self.bit_writer.writeBits(value, 3);
}
// Write a block of tokens with the smallest encoding. Will choose block type.
// The original input can be supplied, and if the huffman encoded data
// is larger than the original bytes, the data will be written as a
// stored block.
// If the input is null, the tokens will always be Huffman encoded.
pub fn write(self: *Self, tokens: []const Token, eof: bool, input: ?[]const u8) Error!void {
const lit_and_dist = self.indexTokens(tokens);
const num_literals = lit_and_dist.num_literals;
const num_distances = lit_and_dist.num_distances;
var extra_bits: u32 = 0;
const ret = storedSizeFits(input);
const stored_size = ret.size;
const storable = ret.storable;
if (storable) {
// We only bother calculating the costs of the extra bits required by
// the length of distance fields (which will be the same for both fixed
// and dynamic encoding), if we need to compare those two encodings
// against stored encoding.
var length_code: u16 = Token.length_codes_start + 8;
while (length_code < num_literals) : (length_code += 1) {
// First eight length codes have extra size = 0.
extra_bits += @as(u32, @intCast(self.literal_freq[length_code])) *
@as(u32, @intCast(Token.lengthExtraBits(length_code)));
}
var distance_code: u16 = 4;
while (distance_code < num_distances) : (distance_code += 1) {
// First four distance codes have extra size = 0.
extra_bits += @as(u32, @intCast(self.distance_freq[distance_code])) *
@as(u32, @intCast(Token.distanceExtraBits(distance_code)));
}
}
// Figure out smallest code.
// Fixed Huffman baseline.
var literal_encoding = &self.fixed_literal_encoding;
var distance_encoding = &self.fixed_distance_encoding;
var size = self.fixedSize(extra_bits);
// Dynamic Huffman?
var num_codegens: u32 = 0;
// Generate codegen and codegenFrequencies, which indicates how to encode
// the literal_encoding and the distance_encoding.
self.generateCodegen(
num_literals,
num_distances,
&self.literal_encoding,
&self.distance_encoding,
);
self.codegen_encoding.generate(self.codegen_freq[0..], 7);
const dynamic_size = self.dynamicSize(
&self.literal_encoding,
&self.distance_encoding,
extra_bits,
);
const dyn_size = dynamic_size.size;
num_codegens = dynamic_size.num_codegens;
if (dyn_size < size) {
size = dyn_size;
literal_encoding = &self.literal_encoding;
distance_encoding = &self.distance_encoding;
}
// Stored bytes?
if (storable and stored_size < size) {
try self.storedBlock(input.?, eof);
return;
}
// Huffman.
if (@intFromPtr(literal_encoding) == @intFromPtr(&self.fixed_literal_encoding)) {
try self.fixedHeader(eof);
} else {
try self.dynamicHeader(num_literals, num_distances, num_codegens, eof);
}
// Write the tokens.
try self.writeTokens(tokens, &literal_encoding.codes, &distance_encoding.codes);
}
pub fn storedBlock(self: *Self, input: []const u8, eof: bool) Error!void {
try self.storedHeader(input.len, eof);
try self.bit_writer.writeBytes(input);
}
// writeBlockDynamic encodes a block using a dynamic Huffman table.
// This should be used if the symbols used have a disproportionate
// histogram distribution.
// If input is supplied and the compression savings are below 1/16th of the
// input size the block is stored.
fn dynamicBlock(
self: *Self,
tokens: []const Token,
eof: bool,
input: ?[]const u8,
) Error!void {
const total_tokens = self.indexTokens(tokens);
const num_literals = total_tokens.num_literals;
const num_distances = total_tokens.num_distances;
// Generate codegen and codegenFrequencies, which indicates how to encode
// the literal_encoding and the distance_encoding.
self.generateCodegen(
num_literals,
num_distances,
&self.literal_encoding,
&self.distance_encoding,
);
self.codegen_encoding.generate(self.codegen_freq[0..], 7);
const dynamic_size = self.dynamicSize(&self.literal_encoding, &self.distance_encoding, 0);
const size = dynamic_size.size;
const num_codegens = dynamic_size.num_codegens;
// Store bytes, if we don't get a reasonable improvement.
const stored_size = storedSizeFits(input);
const ssize = stored_size.size;
const storable = stored_size.storable;
if (storable and ssize < (size + (size >> 4))) {
try self.storedBlock(input.?, eof);
return;
}
// Write Huffman table.
try self.dynamicHeader(num_literals, num_distances, num_codegens, eof);
// Write the tokens.
try self.writeTokens(tokens, &self.literal_encoding.codes, &self.distance_encoding.codes);
}
const TotalIndexedTokens = struct {
num_literals: u32,
num_distances: u32,
};
// Indexes a slice of tokens followed by an end_block_marker, and updates
// literal_freq and distance_freq, and generates literal_encoding
// and distance_encoding.
// The number of literal and distance tokens is returned.
fn indexTokens(self: *Self, tokens: []const Token) TotalIndexedTokens {
var num_literals: u32 = 0;
var num_distances: u32 = 0;
for (self.literal_freq, 0..) |_, i| {
self.literal_freq[i] = 0;
}
for (self.distance_freq, 0..) |_, i| {
self.distance_freq[i] = 0;
}
for (tokens) |t| {
if (t.kind == Token.Kind.literal) {
self.literal_freq[t.literal()] += 1;
continue;
}
self.literal_freq[t.lengthCode()] += 1;
self.distance_freq[t.distanceCode()] += 1;
}
// add end_block_marker token at the end
self.literal_freq[consts.end_block_marker] += 1;
// get the number of literals
num_literals = @as(u32, @intCast(self.literal_freq.len));
while (self.literal_freq[num_literals - 1] == 0) {
num_literals -= 1;
}
// get the number of distances
num_distances = @as(u32, @intCast(self.distance_freq.len));
while (num_distances > 0 and self.distance_freq[num_distances - 1] == 0) {
num_distances -= 1;
}
if (num_distances == 0) {
// We haven't found a single match. If we want to go with the dynamic encoding,
// we should count at least one distance to be sure that the distance huffman tree could be encoded.
self.distance_freq[0] = 1;
num_distances = 1;
}
self.literal_encoding.generate(&self.literal_freq, 15);
self.distance_encoding.generate(&self.distance_freq, 15);
return TotalIndexedTokens{
.num_literals = num_literals,
.num_distances = num_distances,
};
}
// Writes a slice of tokens to the output followed by and end_block_marker.
// codes for literal and distance encoding must be supplied.
fn writeTokens(
self: *Self,
tokens: []const Token,
le_codes: []hc.HuffCode,
oe_codes: []hc.HuffCode,
) Error!void {
for (tokens) |t| {
if (t.kind == Token.Kind.literal) {
try self.writeCode(le_codes[t.literal()]);
continue;
}
// Write the length
const le = t.lengthEncoding();
try self.writeCode(le_codes[le.code]);
if (le.extra_bits > 0) {
try self.bit_writer.writeBits(le.extra_length, le.extra_bits);
}
// Write the distance
const oe = t.distanceEncoding();
try self.writeCode(oe_codes[oe.code]);
if (oe.extra_bits > 0) {
try self.bit_writer.writeBits(oe.extra_distance, oe.extra_bits);
}
}
// add end_block_marker at the end
try self.writeCode(le_codes[consts.end_block_marker]);
}
// Encodes a block of bytes as either Huffman encoded literals or uncompressed bytes
// if the results only gains very little from compression.
pub fn huffmanBlock(self: *Self, input: []const u8, eof: bool) Error!void {
// Add everything as literals
histogram(input, &self.literal_freq);
self.literal_freq[consts.end_block_marker] = 1;
const num_literals = consts.end_block_marker + 1;
self.distance_freq[0] = 1;
const num_distances = 1;
self.literal_encoding.generate(&self.literal_freq, 15);
// Figure out smallest code.
// Always use dynamic Huffman or Store
var num_codegens: u32 = 0;
// Generate codegen and codegenFrequencies, which indicates how to encode
// the literal_encoding and the distance_encoding.
self.generateCodegen(
num_literals,
num_distances,
&self.literal_encoding,
&self.huff_distance,
);
self.codegen_encoding.generate(self.codegen_freq[0..], 7);
const dynamic_size = self.dynamicSize(&self.literal_encoding, &self.huff_distance, 0);
const size = dynamic_size.size;
num_codegens = dynamic_size.num_codegens;
// Store bytes, if we don't get a reasonable improvement.
const stored_size_ret = storedSizeFits(input);
const ssize = stored_size_ret.size;
const storable = stored_size_ret.storable;
if (storable and ssize < (size + (size >> 4))) {
try self.storedBlock(input, eof);
return;
}
// Huffman.
try self.dynamicHeader(num_literals, num_distances, num_codegens, eof);
const encoding = self.literal_encoding.codes[0..257];
for (input) |t| {
const c = encoding[t];
try self.bit_writer.writeBits(c.code, c.len);
}
try self.writeCode(encoding[consts.end_block_marker]);
}
// histogram accumulates a histogram of b in h.
fn histogram(b: []const u8, h: *[286]u16) void {
// Clear histogram
for (h, 0..) |_, i| {
h[i] = 0;
}
var lh = h.*[0..256];
for (b) |t| {
lh[t] += 1;
}
}
};
}
// tests
const expect = std.testing.expect;
const fmt = std.fmt;
const testing = std.testing;
const ArrayList = std.ArrayList;
const TestCase = @import("testdata/block_writer.zig").TestCase;
const testCases = @import("testdata/block_writer.zig").testCases;
// tests if the writeBlock encoding has changed.
test "flate.BlockWriter write" {
inline for (0..testCases.len) |i| {
try testBlock(testCases[i], .write_block);
}
}
// tests if the writeBlockDynamic encoding has changed.
test "flate.BlockWriter dynamicBlock" {
inline for (0..testCases.len) |i| {
try testBlock(testCases[i], .write_dyn_block);
}
}
test "flate.BlockWriter huffmanBlock" {
inline for (0..testCases.len) |i| {
try testBlock(testCases[i], .write_huffman_block);
}
try testBlock(.{
.tokens = &[_]Token{},
.input = "huffman-rand-max.input",
.want = "huffman-rand-max.{s}.expect",
}, .write_huffman_block);
}
const TestFn = enum {
write_block,
write_dyn_block, // write dynamic block
write_huffman_block,
fn to_s(self: TestFn) []const u8 {
return switch (self) {
.write_block => "wb",
.write_dyn_block => "dyn",
.write_huffman_block => "huff",
};
}
fn write(
comptime self: TestFn,
bw: anytype,
tok: []const Token,
input: ?[]const u8,
final: bool,
) !void {
switch (self) {
.write_block => try bw.write(tok, final, input),
.write_dyn_block => try bw.dynamicBlock(tok, final, input),
.write_huffman_block => try bw.huffmanBlock(input.?, final),
}
try bw.flush();
}
};
// testBlock tests a block against its references
//
// size
// 64K [file-name].input - input non compressed file
// 8.1K [file-name].golden -
// 78 [file-name].dyn.expect - output with writeBlockDynamic
// 78 [file-name].wb.expect - output with writeBlock
// 8.1K [file-name].huff.expect - output with writeBlockHuff
// 78 [file-name].dyn.expect-noinput - output with writeBlockDynamic when input is null
// 78 [file-name].wb.expect-noinput - output with writeBlock when input is null
//
// wb - writeBlock
// dyn - writeBlockDynamic
// huff - writeBlockHuff
//
fn testBlock(comptime tc: TestCase, comptime tfn: TestFn) !void {
if (tc.input.len != 0 and tc.want.len != 0) {
const want_name = comptime fmt.comptimePrint(tc.want, .{tfn.to_s()});
const input = @embedFile("testdata/block_writer/" ++ tc.input);
const want = @embedFile("testdata/block_writer/" ++ want_name);
try testWriteBlock(tfn, input, want, tc.tokens);
}
if (tfn == .write_huffman_block) {
return;
}
const want_name_no_input = comptime fmt.comptimePrint(tc.want_no_input, .{tfn.to_s()});
const want = @embedFile("testdata/block_writer/" ++ want_name_no_input);
try testWriteBlock(tfn, null, want, tc.tokens);
}
// Uses writer function `tfn` to write `tokens`, tests that we got `want` as output.
fn testWriteBlock(comptime tfn: TestFn, input: ?[]const u8, want: []const u8, tokens: []const Token) !void {
var buf = ArrayList(u8).init(testing.allocator);
var bw = blockWriter(buf.writer());
try tfn.write(&bw, tokens, input, false);
var got = buf.items;
try testing.expectEqualSlices(u8, want, got); // expect writeBlock to yield expected result
try expect(got[0] & 0b0000_0001 == 0); // bfinal is not set
//
// Test if the writer produces the same output after reset.
buf.deinit();
buf = ArrayList(u8).init(testing.allocator);
defer buf.deinit();
bw.setWriter(buf.writer());
try tfn.write(&bw, tokens, input, true);
try bw.flush();
got = buf.items;
try expect(got[0] & 1 == 1); // bfinal is set
buf.items[0] &= 0b1111_1110; // remove bfinal bit, so we can run test slices
try testing.expectEqualSlices(u8, want, got); // expect writeBlock to yield expected result
}

49
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pub const deflate = struct {
// Number of tokens to accumlate in deflate before starting block encoding.
//
// In zlib this depends on memlevel: 6 + memlevel, where default memlevel is
// 8 and max 9 that gives 14 or 15 bits.
pub const tokens = 1 << 15;
};
pub const match = struct {
pub const base_length = 3; // smallest match length per the RFC section 3.2.5
pub const min_length = 4; // min length used in this algorithm
pub const max_length = 258;
pub const min_distance = 1;
pub const max_distance = 32768;
};
pub const history = struct {
pub const len = match.max_distance;
};
pub const lookup = struct {
pub const bits = 15;
pub const len = 1 << bits;
pub const shift = 32 - bits;
};
pub const huffman = struct {
// The odd order in which the codegen code sizes are written.
pub const codegen_order = [_]u32{ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
// The number of codegen codes.
pub const codegen_code_count = 19;
// The largest distance code.
pub const distance_code_count = 30;
// Maximum number of literals.
pub const max_num_lit = 286;
// Max number of frequencies used for a Huffman Code
// Possible lengths are codegen_code_count (19), distance_code_count (30) and max_num_lit (286).
// The largest of these is max_num_lit.
pub const max_num_frequencies = max_num_lit;
// Biggest block size for uncompressed block.
pub const max_store_block_size = 65535;
// The special code used to mark the end of a block.
pub const end_block_marker = 256;
};

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lib/std/compress/flate/container.zig Normal file
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//! Container of the deflate bit stream body. Container adds header before
//! deflate bit stream and footer after. It can bi gzip, zlib or raw (no header,
//! no footer, raw bit stream).
//!
//! Zlib format is defined in rfc 1950. Header has 2 bytes and footer 4 bytes
//! addler 32 checksum.
//!
//! Gzip format is defined in rfc 1952. Header has 10+ bytes and footer 4 bytes
//! crc32 checksum and 4 bytes of uncompressed data length.
//!
//!
//! rfc 1950: https://datatracker.ietf.org/doc/html/rfc1950#page-4
//! rfc 1952: https://datatracker.ietf.org/doc/html/rfc1952#page-5
//!
const std = @import("std");
pub const Container = enum {
raw, // no header or footer
gzip, // gzip header and footer
zlib, // zlib header and footer
pub fn size(w: Container) usize {
return headerSize(w) + footerSize(w);
}
pub fn headerSize(w: Container) usize {
return switch (w) {
.gzip => 10,
.zlib => 2,
.raw => 0,
};
}
pub fn footerSize(w: Container) usize {
return switch (w) {
.gzip => 8,
.zlib => 4,
.raw => 0,
};
}
pub const list = [_]Container{ .raw, .gzip, .zlib };
pub const Error = error{
BadGzipHeader,
BadZlibHeader,
WrongGzipChecksum,
WrongGzipSize,
WrongZlibChecksum,
};
pub fn writeHeader(comptime wrap: Container, writer: anytype) !void {
switch (wrap) {
.gzip => {
// GZIP 10 byte header (https://datatracker.ietf.org/doc/html/rfc1952#page-5):
// - ID1 (IDentification 1), always 0x1f
// - ID2 (IDentification 2), always 0x8b
// - CM (Compression Method), always 8 = deflate
// - FLG (Flags), all set to 0
// - 4 bytes, MTIME (Modification time), not used, all set to zero
// - XFL (eXtra FLags), all set to zero
// - OS (Operating System), 03 = Unix
const gzipHeader = [_]u8{ 0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03 };
try writer.writeAll(&gzipHeader);
},
.zlib => {
// ZLIB has a two-byte header (https://datatracker.ietf.org/doc/html/rfc1950#page-4):
// 1st byte:
// - First four bits is the CINFO (compression info), which is 7 for the default deflate window size.
// - The next four bits is the CM (compression method), which is 8 for deflate.
// 2nd byte:
// - Two bits is the FLEVEL (compression level). Values are: 0=fastest, 1=fast, 2=default, 3=best.
// - The next bit, FDICT, is set if a dictionary is given.
// - The final five FCHECK bits form a mod-31 checksum.
//
// CINFO = 7, CM = 8, FLEVEL = 0b10, FDICT = 0, FCHECK = 0b11100
const zlibHeader = [_]u8{ 0x78, 0b10_0_11100 };
try writer.writeAll(&zlibHeader);
},
.raw => {},
}
}
pub fn writeFooter(comptime wrap: Container, hasher: *Hasher(wrap), writer: anytype) !void {
var bits: [4]u8 = undefined;
switch (wrap) {
.gzip => {
// GZIP 8 bytes footer
// - 4 bytes, CRC32 (CRC-32)
// - 4 bytes, ISIZE (Input SIZE) - size of the original (uncompressed) input data modulo 2^32
std.mem.writeInt(u32, &bits, hasher.chksum(), .little);
try writer.writeAll(&bits);
std.mem.writeInt(u32, &bits, hasher.bytesRead(), .little);
try writer.writeAll(&bits);
},
.zlib => {
// ZLIB (RFC 1950) is big-endian, unlike GZIP (RFC 1952).
// 4 bytes of ADLER32 (Adler-32 checksum)
// Checksum value of the uncompressed data (excluding any
// dictionary data) computed according to Adler-32
// algorithm.
std.mem.writeInt(u32, &bits, hasher.chksum(), .big);
try writer.writeAll(&bits);
},
.raw => {},
}
}
pub fn parseHeader(comptime wrap: Container, reader: anytype) !void {
switch (wrap) {
.gzip => try parseGzipHeader(reader),
.zlib => try parseZlibHeader(reader),
.raw => {},
}
}
fn parseGzipHeader(reader: anytype) !void {
const magic1 = try reader.read(u8);
const magic2 = try reader.read(u8);
const method = try reader.read(u8);
const flags = try reader.read(u8);
try reader.skipBytes(6); // mtime(4), xflags, os
if (magic1 != 0x1f or magic2 != 0x8b or method != 0x08)
return error.BadGzipHeader;
// Flags description: https://www.rfc-editor.org/rfc/rfc1952.html#page-5
if (flags != 0) {
if (flags & 0b0000_0100 != 0) { // FEXTRA
const extra_len = try reader.read(u16);
try reader.skipBytes(extra_len);
}
if (flags & 0b0000_1000 != 0) { // FNAME
try reader.skipStringZ();
}
if (flags & 0b0001_0000 != 0) { // FCOMMENT
try reader.skipStringZ();
}
if (flags & 0b0000_0010 != 0) { // FHCRC
try reader.skipBytes(2);
}
}
}
fn parseZlibHeader(reader: anytype) !void {
const cm = try reader.read(u4);
const cinfo = try reader.read(u4);
_ = try reader.read(u8);
if (cm != 8 or cinfo > 7) {
return error.BadZlibHeader;
}
}
pub fn parseFooter(comptime wrap: Container, hasher: *Hasher(wrap), reader: anytype) !void {
switch (wrap) {
.gzip => {
if (try reader.read(u32) != hasher.chksum()) return error.WrongGzipChecksum;
if (try reader.read(u32) != hasher.bytesRead()) return error.WrongGzipSize;
},
.zlib => {
const chksum: u32 = @byteSwap(hasher.chksum());
if (try reader.read(u32) != chksum) return error.WrongZlibChecksum;
},
.raw => {},
}
}
pub fn Hasher(comptime wrap: Container) type {
const HasherType = switch (wrap) {
.gzip => std.hash.Crc32,
.zlib => std.hash.Adler32,
.raw => struct {
pub fn init() @This() {
return .{};
}
},
};
return struct {
hasher: HasherType = HasherType.init(),
bytes: usize = 0,
const Self = @This();
pub fn update(self: *Self, buf: []const u8) void {
switch (wrap) {
.raw => {},
else => {
self.hasher.update(buf);
self.bytes += buf.len;
},
}
}
pub fn chksum(self: *Self) u32 {
switch (wrap) {
.raw => return 0,
else => return self.hasher.final(),
}
}
pub fn bytesRead(self: *Self) u32 {
return @truncate(self.bytes);
}
};
}
};

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const std = @import("std");
const io = std.io;
const assert = std.debug.assert;
const testing = std.testing;
const expect = testing.expect;
const print = std.debug.print;
const Token = @import("Token.zig");
const consts = @import("consts.zig");
const BlockWriter = @import("block_writer.zig").BlockWriter;
const Container = @import("container.zig").Container;
const SlidingWindow = @import("SlidingWindow.zig");
const Lookup = @import("Lookup.zig");
pub const Options = struct {
level: Level = .default,
};
/// Trades between speed and compression size.
/// Starts with level 4: in [zlib](https://github.com/madler/zlib/blob/abd3d1a28930f89375d4b41408b39f6c1be157b2/deflate.c#L115C1-L117C43)
/// levels 1-3 are using different algorithm to perform faster but with less
/// compression. That is not implemented here.
pub const Level = enum(u4) {
// zig fmt: off
fast = 0xb, level_4 = 4,
level_5 = 5,
default = 0xc, level_6 = 6,
level_7 = 7,
level_8 = 8,
best = 0xd, level_9 = 9,
// zig fmt: on
};
/// Algorithm knobs for each level.
const LevelArgs = struct {
good: u16, // Do less lookups if we already have match of this length.
nice: u16, // Stop looking for better match if we found match with at least this length.
lazy: u16, // Don't do lazy match find if got match with at least this length.
chain: u16, // How many lookups for previous match to perform.
pub fn get(level: Level) LevelArgs {
// zig fmt: off
return switch (level) {
.fast, .level_4 => .{ .good = 4, .lazy = 4, .nice = 16, .chain = 16 },
.level_5 => .{ .good = 8, .lazy = 16, .nice = 32, .chain = 32 },
.default, .level_6 => .{ .good = 8, .lazy = 16, .nice = 128, .chain = 128 },
.level_7 => .{ .good = 8, .lazy = 32, .nice = 128, .chain = 256 },
.level_8 => .{ .good = 32, .lazy = 128, .nice = 258, .chain = 1024 },
.best, .level_9 => .{ .good = 32, .lazy = 258, .nice = 258, .chain = 4096 },
};
// zig fmt: on
}
};
/// Compress plain data from reader into compressed stream written to writer.
pub fn compress(comptime container: Container, reader: anytype, writer: anytype, options: Options) !void {
var c = try compressor(container, writer, options);
try c.compress(reader);
try c.finish();
}
/// Create compressor for writer type.
pub fn compressor(comptime container: Container, writer: anytype, options: Options) !Compressor(
container,
@TypeOf(writer),
) {
return try Compressor(container, @TypeOf(writer)).init(writer, options);
}
/// Compressor type.
pub fn Compressor(comptime container: Container, comptime WriterType: type) type {
const TokenWriterType = BlockWriter(WriterType);
return Deflate(container, WriterType, TokenWriterType);
}
/// Default compression algorithm. Has two steps: tokenization and token
/// encoding.
///
/// Tokenization takes uncompressed input stream and produces list of tokens.
/// Each token can be literal (byte of data) or match (backrefernce to previous
/// data with length and distance). Tokenization accumulators 32K tokens, when
/// full or `flush` is called tokens are passed to the `block_writer`. Level
/// defines how hard (how slow) it tries to find match.
///
/// Block writer will decide which type of deflate block to write (stored, fixed,
/// dynamic) and encode tokens to the output byte stream. Client has to call
/// `finish` to write block with the final bit set.
///
/// Container defines type of header and footer which can be gzip, zlib or raw.
/// They all share same deflate body. Raw has no header or footer just deflate
/// body.
///
/// Compression algorithm explained in rfc-1951 (slightly edited for this case):
///
/// The compressor uses a chained hash table `lookup` to find duplicated
/// strings, using a hash function that operates on 4-byte sequences. At any
/// given point during compression, let XYZW be the next 4 input bytes
/// (lookahead) to be examined (not necessarily all different, of course).
/// First, the compressor examines the hash chain for XYZW. If the chain is
/// empty, the compressor simply writes out X as a literal byte and advances
/// one byte in the input. If the hash chain is not empty, indicating that the
/// sequence XYZW (or, if we are unlucky, some other 4 bytes with the same
/// hash function value) has occurred recently, the compressor compares all
/// strings on the XYZW hash chain with the actual input data sequence
/// starting at the current point, and selects the longest match.
///
/// To improve overall compression, the compressor defers the selection of
/// matches ("lazy matching"): after a match of length N has been found, the
/// compressor searches for a longer match starting at the next input byte. If
/// it finds a longer match, it truncates the previous match to a length of
/// one (thus producing a single literal byte) and then emits the longer
/// match. Otherwise, it emits the original match, and, as described above,
/// advances N bytes before continuing.
///
///
/// Allocates statically ~400K (192K lookup, 128K tokens, 64K window).
///
/// Deflate function accepts BlockWriterType so we can change that in test to test
/// just tokenization part.
///
fn Deflate(comptime container: Container, comptime WriterType: type, comptime BlockWriterType: type) type {
return struct {
lookup: Lookup = .{},
win: SlidingWindow = .{},
tokens: Tokens = .{},
wrt: WriterType,
block_writer: BlockWriterType,
level: LevelArgs,
hasher: container.Hasher() = .{},
// Match and literal at the previous position.
// Used for lazy match finding in processWindow.
prev_match: ?Token = null,
prev_literal: ?u8 = null,
const Self = @This();
pub fn init(wrt: WriterType, options: Options) !Self {
const self = Self{
.wrt = wrt,
.block_writer = BlockWriterType.init(wrt),
.level = LevelArgs.get(options.level),
};
try container.writeHeader(self.wrt);
return self;
}
const FlushOption = enum { none, flush, final };
// Process data in window and create tokens. If token buffer is full
// flush tokens to the token writer. In the case of `flush` or `final`
// option it will process all data from the window. In the `none` case
// it will preserve some data for the next match.
fn tokenize(self: *Self, flush_opt: FlushOption) !void {
// flush - process all data from window
const should_flush = (flush_opt != .none);
// While there is data in active lookahead buffer.
while (self.win.activeLookahead(should_flush)) |lh| {
var step: u16 = 1; // 1 in the case of literal, match length otherwise
const pos: u16 = self.win.pos();
const literal = lh[0]; // literal at current position
const min_len: u16 = if (self.prev_match) |m| m.length() else 0;
// Try to find match at least min_len long.
if (self.findMatch(pos, lh, min_len)) |match| {
// Found better match than previous.
try self.addPrevLiteral();
// Is found match length good enough?
if (match.length() >= self.level.lazy) {
// Don't try to lazy find better match, use this.
step = try self.addMatch(match);
} else {
// Store this match.
self.prev_literal = literal;
self.prev_match = match;
}
} else {
// There is no better match at current pos then it was previous.
// Write previous match or literal.
if (self.prev_match) |m| {
// Write match from previous position.
step = try self.addMatch(m) - 1; // we already advanced 1 from previous position
} else {
// No match at previous postition.
// Write previous literal if any, and remember this literal.
try self.addPrevLiteral();
self.prev_literal = literal;
}
}
// Advance window and add hashes.
self.windowAdvance(step, lh, pos);
}
if (should_flush) {
// In the case of flushing, last few lookahead buffers were smaller then min match len.
// So only last literal can be unwritten.
assert(self.prev_match == null);
try self.addPrevLiteral();
self.prev_literal = null;
try self.flushTokens(flush_opt);
}
}
fn windowAdvance(self: *Self, step: u16, lh: []const u8, pos: u16) void {
// current position is already added in findMatch
self.lookup.bulkAdd(lh[1..], step - 1, pos + 1);
self.win.advance(step);
}
// Add previous literal (if any) to the tokens list.
fn addPrevLiteral(self: *Self) !void {
if (self.prev_literal) |l| try self.addToken(Token.initLiteral(l));
}
// Add match to the tokens list, reset prev pointers.
// Returns length of the added match.
fn addMatch(self: *Self, m: Token) !u16 {
try self.addToken(m);
self.prev_literal = null;
self.prev_match = null;
return m.length();
}
fn addToken(self: *Self, token: Token) !void {
self.tokens.add(token);
if (self.tokens.full()) try self.flushTokens(.none);
}
// Finds largest match in the history window with the data at current pos.
fn findMatch(self: *Self, pos: u16, lh: []const u8, min_len: u16) ?Token {
var len: u16 = min_len;
// Previous location with the same hash (same 4 bytes).
var prev_pos = self.lookup.add(lh, pos);
// Last found match.
var match: ?Token = null;
// How much back-references to try, performance knob.
var chain: usize = self.level.chain;
if (len >= self.level.good) {
// If we've got a match that's good enough, only look in 1/4 the chain.
chain >>= 2;
}
// Hot path loop!
while (prev_pos > 0 and chain > 0) : (chain -= 1) {
const distance = pos - prev_pos;
if (distance > consts.match.max_distance)
break;
const new_len = self.win.match(prev_pos, pos, len);
if (new_len > len) {
match = Token.initMatch(@intCast(distance), new_len);
if (new_len >= self.level.nice) {
// The match is good enough that we don't try to find a better one.
return match;
}
len = new_len;
}
prev_pos = self.lookup.prev(prev_pos);
}
return match;
}
fn flushTokens(self: *Self, flush_opt: FlushOption) !void {
// Pass tokens to the token writer
try self.block_writer.write(self.tokens.tokens(), flush_opt == .final, self.win.tokensBuffer());
// Stored block ensures byte aligment.
// It has 3 bits (final, block_type) and then padding until byte boundary.
// After that everyting is aligned to the boundary in the stored block.
// Empty stored block is Ob000 + (0-7) bits of padding + 0x00 0x00 0xFF 0xFF.
// Last 4 bytes are byte aligned.
if (flush_opt == .flush) {
try self.block_writer.storedBlock("", false);
}
if (flush_opt != .none) {
// Safe to call only when byte aligned or it is OK to add
// padding bits (on last byte of the final block).
try self.block_writer.flush();
}
// Reset internal tokens store.
self.tokens.reset();
// Notify win that tokens are flushed.
self.win.flush();
}
// Slide win and if needed lookup tables.
fn slide(self: *Self) void {
const n = self.win.slide();
self.lookup.slide(n);
}
/// Compresses as much data as possible, stops when the reader becomes
/// empty. It will introduce some output latency (reading input without
/// producing all output) because some data are still in internal
/// buffers.
///
/// It is up to the caller to call flush (if needed) or finish (required)
/// when is need to output any pending data or complete stream.
///
pub fn compress(self: *Self, reader: anytype) !void {
while (true) {
// Fill window from reader
const buf = self.win.writable();
if (buf.len == 0) {
try self.tokenize(.none);
self.slide();
continue;
}
const n = try reader.readAll(buf);
self.hasher.update(buf[0..n]);
self.win.written(n);
// Process window
try self.tokenize(.none);
// Exit when no more data in reader
if (n < buf.len) break;
}
}
/// Flushes internal buffers to the output writer. Outputs empty stored
/// block to sync bit stream to the byte boundary, so that the
/// decompressor can get all input data available so far.
///
/// It is useful mainly in compressed network protocols, to ensure that
/// deflate bit stream can be used as byte stream. May degrade
/// compression so it should be used only when necessary.
///
/// Completes the current deflate block and follows it with an empty
/// stored block that is three zero bits plus filler bits to the next
/// byte, followed by four bytes (00 00 ff ff).
///
pub fn flush(self: *Self) !void {
try self.tokenize(.flush);
}
/// Completes deflate bit stream by writing any pending data as deflate
/// final deflate block. HAS to be called once all data are written to
/// the compressor as a signal that next block has to have final bit
/// set.
///
pub fn finish(self: *Self) !void {
try self.tokenize(.final);
try container.writeFooter(&self.hasher, self.wrt);
}
/// Use another writer while preserving history. Most probably flush
/// should be called on old writer before setting new.
pub fn setWriter(self: *Self, new_writer: WriterType) void {
self.block_writer.setWriter(new_writer);
self.wrt = new_writer;
}
// Writer interface
pub const Writer = io.Writer(*Self, Error, write);
pub const Error = BlockWriterType.Error;
/// Write `input` of uncompressed data.
/// See compress.
pub fn write(self: *Self, input: []const u8) !usize {
var fbs = io.fixedBufferStream(input);
try self.compress(fbs.reader());
return input.len;
}
pub fn writer(self: *Self) Writer {
return .{ .context = self };
}
};
}
// Tokens store
const Tokens = struct {
list: [consts.deflate.tokens]Token = undefined,
pos: usize = 0,
fn add(self: *Tokens, t: Token) void {
self.list[self.pos] = t;
self.pos += 1;
}
fn full(self: *Tokens) bool {
return self.pos == self.list.len;
}
fn reset(self: *Tokens) void {
self.pos = 0;
}
fn tokens(self: *Tokens) []const Token {
return self.list[0..self.pos];
}
};
/// Creates huffman only deflate blocks. Disables Lempel-Ziv match searching and
/// only performs Huffman entropy encoding. Results in faster compression, much
/// less memory requirements during compression but bigger compressed sizes.
pub const huffman = struct {
pub fn compress(comptime container: Container, reader: anytype, writer: anytype) !void {
var c = try huffman.compressor(container, writer);
try c.compress(reader);
try c.finish();
}
pub fn Compressor(comptime container: Container, comptime WriterType: type) type {
return SimpleCompressor(.huffman, container, WriterType);
}
pub fn compressor(comptime container: Container, writer: anytype) !huffman.Compressor(container, @TypeOf(writer)) {
return try huffman.Compressor(container, @TypeOf(writer)).init(writer);
}
};
/// Creates store blocks only. Data are not compressed only packed into deflate
/// store blocks. That adds 9 bytes of header for each block. Max stored block
/// size is 64K. Block is emitted when flush is called on on finish.
pub const store = struct {
pub fn compress(comptime container: Container, reader: anytype, writer: anytype) !void {
var c = try store.compressor(container, writer);
try c.compress(reader);
try c.finish();
}
pub fn Compressor(comptime container: Container, comptime WriterType: type) type {
return SimpleCompressor(.store, container, WriterType);
}
pub fn compressor(comptime container: Container, writer: anytype) !store.Compressor(container, @TypeOf(writer)) {
return try store.Compressor(container, @TypeOf(writer)).init(writer);
}
};
const SimpleCompressorKind = enum {
huffman,
store,
};
fn simpleCompressor(
comptime kind: SimpleCompressorKind,
comptime container: Container,
writer: anytype,
) !SimpleCompressor(kind, container, @TypeOf(writer)) {
return try SimpleCompressor(kind, container, @TypeOf(writer)).init(writer);
}
fn SimpleCompressor(
comptime kind: SimpleCompressorKind,
comptime container: Container,
comptime WriterType: type,
) type {
const BlockWriterType = BlockWriter(WriterType);
return struct {
buffer: [65535]u8 = undefined, // because store blocks are limited to 65535 bytes
wp: usize = 0,
wrt: WriterType,
block_writer: BlockWriterType,
hasher: container.Hasher() = .{},
const Self = @This();
pub fn init(wrt: WriterType) !Self {
const self = Self{
.wrt = wrt,
.block_writer = BlockWriterType.init(wrt),
};
try container.writeHeader(self.wrt);
return self;
}
pub fn flush(self: *Self) !void {
try self.flushBuffer(false);
try self.block_writer.storedBlock("", false);
try self.block_writer.flush();
}
pub fn finish(self: *Self) !void {
try self.flushBuffer(true);
try self.block_writer.flush();
try container.writeFooter(&self.hasher, self.wrt);
}
fn flushBuffer(self: *Self, final: bool) !void {
const buf = self.buffer[0..self.wp];
switch (kind) {
.huffman => try self.block_writer.huffmanBlock(buf, final),
.store => try self.block_writer.storedBlock(buf, final),
}
self.wp = 0;
}
// Writes all data from the input reader of uncompressed data.
// It is up to the caller to call flush or finish if there is need to
// output compressed blocks.
pub fn compress(self: *Self, reader: anytype) !void {
while (true) {
// read from rdr into buffer
const buf = self.buffer[self.wp..];
if (buf.len == 0) {
try self.flushBuffer(false);
continue;
}
const n = try reader.readAll(buf);
self.hasher.update(buf[0..n]);
self.wp += n;
if (n < buf.len) break; // no more data in reader
}
}
// Writer interface
pub const Writer = io.Writer(*Self, Error, write);
pub const Error = BlockWriterType.Error;
// Write `input` of uncompressed data.
pub fn write(self: *Self, input: []const u8) !usize {
var fbs = io.fixedBufferStream(input);
try self.compress(fbs.reader());
return input.len;
}
pub fn writer(self: *Self) Writer {
return .{ .context = self };
}
};
}
const builtin = @import("builtin");
test "flate.Deflate tokenization" {
if (builtin.target.cpu.arch == .wasm32) return error.SkipZigTest;
const L = Token.initLiteral;
const M = Token.initMatch;
const cases = [_]struct {
data: []const u8,
tokens: []const Token,
}{
.{
.data = "Blah blah blah blah blah!",
.tokens = &[_]Token{ L('B'), L('l'), L('a'), L('h'), L(' '), L('b'), M(5, 18), L('!') },
},
.{
.data = "ABCDEABCD ABCDEABCD",
.tokens = &[_]Token{
L('A'), L('B'), L('C'), L('D'), L('E'), L('A'), L('B'), L('C'), L('D'), L(' '),
L('A'), M(10, 8),
},
},
};
for (cases) |c| {
inline for (Container.list) |container| { // for each wrapping
var cw = io.countingWriter(io.null_writer);
const cww = cw.writer();
var df = try Deflate(container, @TypeOf(cww), TestTokenWriter).init(cww, .{});
_ = try df.write(c.data);
try df.flush();
// df.token_writer.show();
try expect(df.block_writer.pos == c.tokens.len); // number of tokens written
try testing.expectEqualSlices(Token, df.block_writer.get(), c.tokens); // tokens match
try testing.expectEqual(container.headerSize(), cw.bytes_written);
try df.finish();
try testing.expectEqual(container.size(), cw.bytes_written);
}
}
}
// Tests that tokens writen are equal to expected token list.
const TestTokenWriter = struct {
const Self = @This();
pos: usize = 0,
actual: [128]Token = undefined,
pub fn init(_: anytype) Self {
return .{};
}
pub fn write(self: *Self, tokens: []const Token, _: bool, _: ?[]const u8) !void {
for (tokens) |t| {
self.actual[self.pos] = t;
self.pos += 1;
}
}
pub fn storedBlock(_: *Self, _: []const u8, _: bool) !void {}
pub fn get(self: *Self) []Token {
return self.actual[0..self.pos];
}
pub fn show(self: *Self) void {
print("\n", .{});
for (self.get()) |t| {
t.show();
}
}
pub fn flush(_: *Self) !void {}
};
test "flate deflate file tokenization" {
if (builtin.target.cpu.arch == .wasm32) return error.SkipZigTest;
const levels = [_]Level{ .level_4, .level_5, .level_6, .level_7, .level_8, .level_9 };
const cases = [_]struct {
data: []const u8, // uncompressed content
// expected number of tokens producet in deflate tokenization
tokens_count: [levels.len]usize = .{0} ** levels.len,
}{
.{
.data = @embedFile("testdata/rfc1951.txt"),
.tokens_count = .{ 7675, 7672, 7599, 7594, 7598, 7599 },
},
.{
.data = @embedFile("testdata/block_writer/huffman-null-max.input"),
.tokens_count = .{ 257, 257, 257, 257, 257, 257 },
},
.{
.data = @embedFile("testdata/block_writer/huffman-pi.input"),
.tokens_count = .{ 2570, 2564, 2564, 2564, 2564, 2564 },
},
.{
.data = @embedFile("testdata/block_writer/huffman-text.input"),
.tokens_count = .{ 235, 234, 234, 234, 234, 234 },
},
.{
.data = @embedFile("testdata/fuzz/roundtrip1.input"),
.tokens_count = .{ 333, 331, 331, 331, 331, 331 },
},
.{
.data = @embedFile("testdata/fuzz/roundtrip2.input"),
.tokens_count = .{ 334, 334, 334, 334, 334, 334 },
},
};
for (cases) |case| { // for each case
const data = case.data;
for (levels, 0..) |level, i| { // for each compression level
var original = io.fixedBufferStream(data);
// buffer for decompressed data
var al = std.ArrayList(u8).init(testing.allocator);
defer al.deinit();
const writer = al.writer();
// create compressor
const WriterType = @TypeOf(writer);
const TokenWriter = TokenDecoder(@TypeOf(writer));
var cmp = try Deflate(.raw, WriterType, TokenWriter).init(writer, .{ .level = level });
// Stream uncompressed `orignal` data to the compressor. It will
// produce tokens list and pass that list to the TokenDecoder. This
// TokenDecoder uses CircularBuffer from inflate to convert list of
// tokens back to the uncompressed stream.
try cmp.compress(original.reader());
try cmp.flush();
const expected_count = case.tokens_count[i];
const actual = cmp.block_writer.tokens_count;
if (expected_count == 0) {
print("actual token count {d}\n", .{actual});
} else {
try testing.expectEqual(expected_count, actual);
}
try testing.expectEqual(data.len, al.items.len);
try testing.expectEqualSlices(u8, data, al.items);
}
}
}
fn TokenDecoder(comptime WriterType: type) type {
return struct {
const CircularBuffer = @import("CircularBuffer.zig");
hist: CircularBuffer = .{},
wrt: WriterType,
tokens_count: usize = 0,
const Self = @This();
pub fn init(wrt: WriterType) Self {
return .{ .wrt = wrt };
}
pub fn write(self: *Self, tokens: []const Token, _: bool, _: ?[]const u8) !void {
self.tokens_count += tokens.len;
for (tokens) |t| {
switch (t.kind) {
.literal => self.hist.write(t.literal()),
.match => try self.hist.writeMatch(t.length(), t.distance()),
}
if (self.hist.free() < 285) try self.flushWin();
}
try self.flushWin();
}
pub fn storedBlock(_: *Self, _: []const u8, _: bool) !void {}
fn flushWin(self: *Self) !void {
while (true) {
const buf = self.hist.read();
if (buf.len == 0) break;
try self.wrt.writeAll(buf);
}
}
pub fn flush(_: *Self) !void {}
};
}
test "flate.Deflate store simple compressor" {
const data = "Hello world!";
const expected = [_]u8{
0x1, // block type 0, final bit set
0xc, 0x0, // len = 12
0xf3, 0xff, // ~len
'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '!', //
//0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x77, 0x6f, 0x72, 0x6c, 0x64, 0x21,
};
var fbs = std.io.fixedBufferStream(data);
var al = std.ArrayList(u8).init(testing.allocator);
defer al.deinit();
var cmp = try store.compressor(.raw, al.writer());
try cmp.compress(fbs.reader());
try cmp.finish();
try testing.expectEqualSlices(u8, &expected, al.items);
fbs.reset();
try al.resize(0);
// huffman only compresoor will also emit store block for this small sample
var hc = try huffman.compressor(.raw, al.writer());
try hc.compress(fbs.reader());
try hc.finish();
try testing.expectEqualSlices(u8, &expected, al.items);
}

308
lib/std/compress/flate/huffman_decoder.zig Normal file
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@@ -0,0 +1,308 @@
const std = @import("std");
const testing = std.testing;
pub const Symbol = packed struct {
pub const Kind = enum(u2) {
literal,
end_of_block,
match,
};
symbol: u8 = 0, // symbol from alphabet
code_bits: u4 = 0, // number of bits in code 0-15
kind: Kind = .literal,
code: u16 = 0, // huffman code of the symbol
next: u16 = 0, // pointer to the next symbol in linked list
// it is safe to use 0 as null pointer, when sorted 0 has shortest code and fits into lookup
// Sorting less than function.
pub fn asc(_: void, a: Symbol, b: Symbol) bool {
if (a.code_bits == b.code_bits) {
if (a.kind == b.kind) {
return a.symbol < b.symbol;
}
return @intFromEnum(a.kind) < @intFromEnum(b.kind);
}
return a.code_bits < b.code_bits;
}
};
pub const LiteralDecoder = HuffmanDecoder(286, 15, 9);
pub const DistanceDecoder = HuffmanDecoder(30, 15, 9);
pub const CodegenDecoder = HuffmanDecoder(19, 7, 7);
pub const Error = error{
InvalidCode,
OversubscribedHuffmanTree,
IncompleteHuffmanTree,
MissingEndOfBlockCode,
};
/// Creates huffman tree codes from list of code lengths (in `build`).
///
/// `find` then finds symbol for code bits. Code can be any length between 1 and
/// 15 bits. When calling `find` we don't know how many bits will be used to
/// find symbol. When symbol is returned it has code_bits field which defines
/// how much we should advance in bit stream.
///
/// Lookup table is used to map 15 bit int to symbol. Same symbol is written
/// many times in this table; 32K places for 286 (at most) symbols.
/// Small lookup table is optimization for faster search.
/// It is variation of the algorithm explained in [zlib](https://github.com/madler/zlib/blob/643e17b7498d12ab8d15565662880579692f769d/doc/algorithm.txt#L92)
/// with difference that we here use statically allocated arrays.
///
fn HuffmanDecoder(
comptime alphabet_size: u16,
comptime max_code_bits: u4,
comptime lookup_bits: u4,
) type {
const lookup_shift = max_code_bits - lookup_bits;
return struct {
// all symbols in alaphabet, sorted by code_len, symbol
symbols: [alphabet_size]Symbol = undefined,
// lookup table code -> symbol
lookup: [1 << lookup_bits]Symbol = undefined,
const Self = @This();
/// Generates symbols and lookup tables from list of code lens for each symbol.
pub fn generate(self: *Self, lens: []const u4) !void {
try checkCompletnes(lens);
// init alphabet with code_bits
for (self.symbols, 0..) |_, i| {
const cb: u4 = if (i < lens.len) lens[i] else 0;
self.symbols[i] = if (i < 256)
.{ .kind = .literal, .symbol = @intCast(i), .code_bits = cb }
else if (i == 256)
.{ .kind = .end_of_block, .symbol = 0xff, .code_bits = cb }
else
.{ .kind = .match, .symbol = @intCast(i - 257), .code_bits = cb };
}
std.sort.heap(Symbol, &self.symbols, {}, Symbol.asc);
// reset lookup table
for (0..self.lookup.len) |i| {
self.lookup[i] = .{};
}
// assign code to symbols
// reference: https://youtu.be/9_YEGLe33NA?list=PLU4IQLU9e_OrY8oASHx0u3IXAL9TOdidm&t=2639
var code: u16 = 0;
var idx: u16 = 0;
for (&self.symbols, 0..) |*sym, pos| {
//print("sym: {}\n", .{sym});
if (sym.code_bits == 0) continue; // skip unused
sym.code = code;
const next_code = code + (@as(u16, 1) << (max_code_bits - sym.code_bits));
const next_idx = next_code >> lookup_shift;
if (next_idx > self.lookup.len or idx >= self.lookup.len) break;
if (sym.code_bits <= lookup_bits) {
// fill small lookup table
for (idx..next_idx) |j|
self.lookup[j] = sym.*;
} else {
// insert into linked table starting at root
const root = &self.lookup[idx];
const root_next = root.next;
root.next = @intCast(pos);
sym.next = root_next;
}
idx = next_idx;
code = next_code;
}
//print("decoder generate, code: {d}, idx: {d}\n", .{ code, idx });
}
/// Given the list of code lengths check that it represents a canonical
/// Huffman code for n symbols.
///
/// Reference: https://github.com/madler/zlib/blob/5c42a230b7b468dff011f444161c0145b5efae59/contrib/puff/puff.c#L340
fn checkCompletnes(lens: []const u4) !void {
if (alphabet_size == 286)
if (lens[256] == 0) return error.MissingEndOfBlockCode;
var count = [_]u16{0} ** (@as(usize, max_code_bits) + 1);
var max: usize = 0;
for (lens) |n| {
if (n == 0) continue;
if (n > max) max = n;
count[n] += 1;
}
if (max == 0) // emtpy tree
return;
// check for an over-subscribed or incomplete set of lengths
var left: usize = 1; // one possible code of zero length
for (1..count.len) |len| {
left <<= 1; // one more bit, double codes left
if (count[len] > left)
return error.OversubscribedHuffmanTree;
left -= count[len]; // deduct count from possible codes
}
if (left > 0) { // left > 0 means incomplete
// incomplete code ok only for single length 1 code
if (max_code_bits > 7 and max == count[0] + count[1]) return;
return error.IncompleteHuffmanTree;
}
}
/// Finds symbol for lookup table code.
pub fn find(self: *Self, code: u16) !Symbol {
// try to find in lookup table
const idx = code >> lookup_shift;
const sym = self.lookup[idx];
if (sym.code_bits != 0) return sym;
// if not use linked list of symbols with same prefix
return self.findLinked(code, sym.next);
}
inline fn findLinked(self: *Self, code: u16, start: u16) !Symbol {
var pos = start;
while (pos > 0) {
const sym = self.symbols[pos];
const shift = max_code_bits - sym.code_bits;
// compare code_bits number of upper bits
if ((code ^ sym.code) >> shift == 0) return sym;
pos = sym.next;
}
return error.InvalidCode;
}
};
}
test "flate.HuffmanDecoder init/find" {
// example data from: https://youtu.be/SJPvNi4HrWQ?t=8423
const code_lens = [_]u4{ 4, 3, 0, 2, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 3, 2 };
var h: CodegenDecoder = .{};
try h.generate(&code_lens);
const expected = [_]struct {
sym: Symbol,
code: u16,
}{
.{
.code = 0b00_00000,
.sym = .{ .symbol = 3, .code_bits = 2 },
},
.{
.code = 0b01_00000,
.sym = .{ .symbol = 18, .code_bits = 2 },
},
.{
.code = 0b100_0000,
.sym = .{ .symbol = 1, .code_bits = 3 },
},
.{
.code = 0b101_0000,
.sym = .{ .symbol = 4, .code_bits = 3 },
},
.{
.code = 0b110_0000,
.sym = .{ .symbol = 17, .code_bits = 3 },
},
.{
.code = 0b1110_000,
.sym = .{ .symbol = 0, .code_bits = 4 },
},
.{
.code = 0b1111_000,
.sym = .{ .symbol = 16, .code_bits = 4 },
},
};
// unused symbols
for (0..12) |i| {
try testing.expectEqual(0, h.symbols[i].code_bits);
}
// used, from index 12
for (expected, 12..) |e, i| {
try testing.expectEqual(e.sym.symbol, h.symbols[i].symbol);
try testing.expectEqual(e.sym.code_bits, h.symbols[i].code_bits);
const sym_from_code = try h.find(e.code);
try testing.expectEqual(e.sym.symbol, sym_from_code.symbol);
}
// All possible codes for each symbol.
// Lookup table has 126 elements, to cover all possible 7 bit codes.
for (0b0000_000..0b0100_000) |c| // 0..32 (32)
try testing.expectEqual(3, (try h.find(@intCast(c))).symbol);
for (0b0100_000..0b1000_000) |c| // 32..64 (32)
try testing.expectEqual(18, (try h.find(@intCast(c))).symbol);
for (0b1000_000..0b1010_000) |c| // 64..80 (16)
try testing.expectEqual(1, (try h.find(@intCast(c))).symbol);
for (0b1010_000..0b1100_000) |c| // 80..96 (16)
try testing.expectEqual(4, (try h.find(@intCast(c))).symbol);
for (0b1100_000..0b1110_000) |c| // 96..112 (16)
try testing.expectEqual(17, (try h.find(@intCast(c))).symbol);
for (0b1110_000..0b1111_000) |c| // 112..120 (8)
try testing.expectEqual(0, (try h.find(@intCast(c))).symbol);
for (0b1111_000..0b1_0000_000) |c| // 120...128 (8)
try testing.expectEqual(16, (try h.find(@intCast(c))).symbol);
}
const print = std.debug.print;
const assert = std.debug.assert;
const expect = std.testing.expect;
test "flate.HuffmanDecoder encode/decode literals" {
const LiteralEncoder = @import("huffman_encoder.zig").LiteralEncoder;
for (1..286) |j| { // for all different number of codes
var enc: LiteralEncoder = .{};
// create freqencies
var freq = [_]u16{0} ** 286;
freq[256] = 1; // ensure we have end of block code
for (&freq, 1..) |*f, i| {
if (i % j == 0)
f.* = @intCast(i);
}
// encoder from freqencies
enc.generate(&freq, 15);
// get code_lens from encoder
var code_lens = [_]u4{0} ** 286;
for (code_lens, 0..) |_, i| {
code_lens[i] = @intCast(enc.codes[i].len);
}
// generate decoder from code lens
var dec: LiteralDecoder = .{};
try dec.generate(&code_lens);
// expect decoder code to match original encoder code
for (dec.symbols) |s| {
if (s.code_bits == 0) continue;
const c_code: u16 = @bitReverse(@as(u15, @intCast(s.code)));
const symbol: u16 = switch (s.kind) {
.literal => s.symbol,
.end_of_block => 256,
.match => @as(u16, s.symbol) + 257,
};
const c = enc.codes[symbol];
try expect(c.code == c_code);
}
// find each symbol by code
for (enc.codes) |c| {
if (c.len == 0) continue;
const s_code: u15 = @bitReverse(@as(u15, @intCast(c.code)));
const s = try dec.find(s_code);
try expect(s.code == s_code);
try expect(s.code_bits == c.len);
}
}
}

536
lib/std/compress/flate/huffman_encoder.zig Normal file
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const std = @import("std");
const assert = std.debug.assert;
const math = std.math;
const mem = std.mem;
const sort = std.sort;
const testing = std.testing;
const consts = @import("consts.zig").huffman;
const LiteralNode = struct {
literal: u16,
freq: u16,
};
// Describes the state of the constructed tree for a given depth.
const LevelInfo = struct {
// Our level. for better printing
level: u32,
// The frequency of the last node at this level
last_freq: u32,
// The frequency of the next character to add to this level
next_char_freq: u32,
// The frequency of the next pair (from level below) to add to this level.
// Only valid if the "needed" value of the next lower level is 0.
next_pair_freq: u32,
// The number of chains remaining to generate for this level before moving
// up to the next level
needed: u32,
};
// hcode is a huffman code with a bit code and bit length.
pub const HuffCode = struct {
code: u16 = 0,
len: u16 = 0,
// set sets the code and length of an hcode.
fn set(self: *HuffCode, code: u16, length: u16) void {
self.len = length;
self.code = code;
}
};
pub fn HuffmanEncoder(comptime size: usize) type {
return struct {
codes: [size]HuffCode = undefined,
// Reusable buffer with the longest possible frequency table.
freq_cache: [consts.max_num_frequencies + 1]LiteralNode = undefined,
bit_count: [17]u32 = undefined,
lns: []LiteralNode = undefined, // sorted by literal, stored to avoid repeated allocation in generate
lfs: []LiteralNode = undefined, // sorted by frequency, stored to avoid repeated allocation in generate
const Self = @This();
// Update this Huffman Code object to be the minimum code for the specified frequency count.
//
// freq An array of frequencies, in which frequency[i] gives the frequency of literal i.
// max_bits The maximum number of bits to use for any literal.
pub fn generate(self: *Self, freq: []u16, max_bits: u32) void {
var list = self.freq_cache[0 .. freq.len + 1];
// Number of non-zero literals
var count: u32 = 0;
// Set list to be the set of all non-zero literals and their frequencies
for (freq, 0..) |f, i| {
if (f != 0) {
list[count] = LiteralNode{ .literal = @as(u16, @intCast(i)), .freq = f };
count += 1;
} else {
list[count] = LiteralNode{ .literal = 0x00, .freq = 0 };
self.codes[i].len = 0;
}
}
list[freq.len] = LiteralNode{ .literal = 0x00, .freq = 0 };
list = list[0..count];
if (count <= 2) {
// Handle the small cases here, because they are awkward for the general case code. With
// two or fewer literals, everything has bit length 1.
for (list, 0..) |node, i| {
// "list" is in order of increasing literal value.
self.codes[node.literal].set(@as(u16, @intCast(i)), 1);
}
return;
}
self.lfs = list;
mem.sort(LiteralNode, self.lfs, {}, byFreq);
// Get the number of literals for each bit count
const bit_count = self.bitCounts(list, max_bits);
// And do the assignment
self.assignEncodingAndSize(bit_count, list);
}
pub fn bitLength(self: *Self, freq: []u16) u32 {
var total: u32 = 0;
for (freq, 0..) |f, i| {
if (f != 0) {
total += @as(u32, @intCast(f)) * @as(u32, @intCast(self.codes[i].len));
}
}
return total;
}
// Return the number of literals assigned to each bit size in the Huffman encoding
//
// This method is only called when list.len >= 3
// The cases of 0, 1, and 2 literals are handled by special case code.
//
// list: An array of the literals with non-zero frequencies
// and their associated frequencies. The array is in order of increasing
// frequency, and has as its last element a special element with frequency
// std.math.maxInt(i32)
//
// max_bits: The maximum number of bits that should be used to encode any literal.
// Must be less than 16.
//
// Returns an integer array in which array[i] indicates the number of literals
// that should be encoded in i bits.
fn bitCounts(self: *Self, list: []LiteralNode, max_bits_to_use: usize) []u32 {
var max_bits = max_bits_to_use;
const n = list.len;
const max_bits_limit = 16;
assert(max_bits < max_bits_limit);
// The tree can't have greater depth than n - 1, no matter what. This
// saves a little bit of work in some small cases
max_bits = @min(max_bits, n - 1);
// Create information about each of the levels.
// A bogus "Level 0" whose sole purpose is so that
// level1.prev.needed == 0. This makes level1.next_pair_freq
// be a legitimate value that never gets chosen.
var levels: [max_bits_limit]LevelInfo = mem.zeroes([max_bits_limit]LevelInfo);
// leaf_counts[i] counts the number of literals at the left
// of ancestors of the rightmost node at level i.
// leaf_counts[i][j] is the number of literals at the left
// of the level j ancestor.
var leaf_counts: [max_bits_limit][max_bits_limit]u32 = mem.zeroes([max_bits_limit][max_bits_limit]u32);
{
var level = @as(u32, 1);
while (level <= max_bits) : (level += 1) {
// For every level, the first two items are the first two characters.
// We initialize the levels as if we had already figured this out.
levels[level] = LevelInfo{
.level = level,
.last_freq = list[1].freq,
.next_char_freq = list[2].freq,
.next_pair_freq = list[0].freq + list[1].freq,
.needed = 0,
};
leaf_counts[level][level] = 2;
if (level == 1) {
levels[level].next_pair_freq = math.maxInt(i32);
}
}
}
// We need a total of 2*n - 2 items at top level and have already generated 2.
levels[max_bits].needed = 2 * @as(u32, @intCast(n)) - 4;
{
var level = max_bits;
while (true) {
var l = &levels[level];
if (l.next_pair_freq == math.maxInt(i32) and l.next_char_freq == math.maxInt(i32)) {
// We've run out of both leafs and pairs.
// End all calculations for this level.
// To make sure we never come back to this level or any lower level,
// set next_pair_freq impossibly large.
l.needed = 0;
levels[level + 1].next_pair_freq = math.maxInt(i32);
level += 1;
continue;
}
const prev_freq = l.last_freq;
if (l.next_char_freq < l.next_pair_freq) {
// The next item on this row is a leaf node.
const next = leaf_counts[level][level] + 1;
l.last_freq = l.next_char_freq;
// Lower leaf_counts are the same of the previous node.
leaf_counts[level][level] = next;
if (next >= list.len) {
l.next_char_freq = maxNode().freq;
} else {
l.next_char_freq = list[next].freq;
}
} else {
// The next item on this row is a pair from the previous row.
// next_pair_freq isn't valid until we generate two
// more values in the level below
l.last_freq = l.next_pair_freq;
// Take leaf counts from the lower level, except counts[level] remains the same.
@memcpy(leaf_counts[level][0..level], leaf_counts[level - 1][0..level]);
levels[l.level - 1].needed = 2;
}
l.needed -= 1;
if (l.needed == 0) {
// We've done everything we need to do for this level.
// Continue calculating one level up. Fill in next_pair_freq
// of that level with the sum of the two nodes we've just calculated on
// this level.
if (l.level == max_bits) {
// All done!
break;
}
levels[l.level + 1].next_pair_freq = prev_freq + l.last_freq;
level += 1;
} else {
// If we stole from below, move down temporarily to replenish it.
while (levels[level - 1].needed > 0) {
level -= 1;
if (level == 0) {
break;
}
}
}
}
}
// Somethings is wrong if at the end, the top level is null or hasn't used
// all of the leaves.
assert(leaf_counts[max_bits][max_bits] == n);
var bit_count = self.bit_count[0 .. max_bits + 1];
var bits: u32 = 1;
const counts = &leaf_counts[max_bits];
{
var level = max_bits;
while (level > 0) : (level -= 1) {
// counts[level] gives the number of literals requiring at least "bits"
// bits to encode.
bit_count[bits] = counts[level] - counts[level - 1];
bits += 1;
if (level == 0) {
break;
}
}
}
return bit_count;
}
// Look at the leaves and assign them a bit count and an encoding as specified
// in RFC 1951 3.2.2
fn assignEncodingAndSize(self: *Self, bit_count: []u32, list_arg: []LiteralNode) void {
var code = @as(u16, 0);
var list = list_arg;
for (bit_count, 0..) |bits, n| {
code <<= 1;
if (n == 0 or bits == 0) {
continue;
}
// The literals list[list.len-bits] .. list[list.len-bits]
// are encoded using "bits" bits, and get the values
// code, code + 1, .... The code values are
// assigned in literal order (not frequency order).
const chunk = list[list.len - @as(u32, @intCast(bits)) ..];
self.lns = chunk;
mem.sort(LiteralNode, self.lns, {}, byLiteral);
for (chunk) |node| {
self.codes[node.literal] = HuffCode{
.code = bitReverse(u16, code, @as(u5, @intCast(n))),
.len = @as(u16, @intCast(n)),
};
code += 1;
}
list = list[0 .. list.len - @as(u32, @intCast(bits))];
}
}
};
}
fn maxNode() LiteralNode {
return LiteralNode{
.literal = math.maxInt(u16),
.freq = math.maxInt(u16),
};
}
pub fn huffmanEncoder(comptime size: u32) HuffmanEncoder(size) {
return .{};
}
pub const LiteralEncoder = HuffmanEncoder(consts.max_num_frequencies);
pub const DistanceEncoder = HuffmanEncoder(consts.distance_code_count);
pub const CodegenEncoder = HuffmanEncoder(19);
// Generates a HuffmanCode corresponding to the fixed literal table
pub fn fixedLiteralEncoder() LiteralEncoder {
var h: LiteralEncoder = undefined;
var ch: u16 = 0;
while (ch < consts.max_num_frequencies) : (ch += 1) {
var bits: u16 = undefined;
var size: u16 = undefined;
switch (ch) {
0...143 => {
// size 8, 000110000 .. 10111111
bits = ch + 48;
size = 8;
},
144...255 => {
// size 9, 110010000 .. 111111111
bits = ch + 400 - 144;
size = 9;
},
256...279 => {
// size 7, 0000000 .. 0010111
bits = ch - 256;
size = 7;
},
else => {
// size 8, 11000000 .. 11000111
bits = ch + 192 - 280;
size = 8;
},
}
h.codes[ch] = HuffCode{ .code = bitReverse(u16, bits, @as(u5, @intCast(size))), .len = size };
}
return h;
}
pub fn fixedDistanceEncoder() DistanceEncoder {
var h: DistanceEncoder = undefined;
for (h.codes, 0..) |_, ch| {
h.codes[ch] = HuffCode{ .code = bitReverse(u16, @as(u16, @intCast(ch)), 5), .len = 5 };
}
return h;
}
pub fn huffmanDistanceEncoder() DistanceEncoder {
var distance_freq = [1]u16{0} ** consts.distance_code_count;
distance_freq[0] = 1;
// huff_distance is a static distance encoder used for huffman only encoding.
// It can be reused since we will not be encoding distance values.
var h: DistanceEncoder = .{};
h.generate(distance_freq[0..], 15);
return h;
}
fn byLiteral(context: void, a: LiteralNode, b: LiteralNode) bool {
_ = context;
return a.literal < b.literal;
}
fn byFreq(context: void, a: LiteralNode, b: LiteralNode) bool {
_ = context;
if (a.freq == b.freq) {
return a.literal < b.literal;
}
return a.freq < b.freq;
}
test "flate.HuffmanEncoder generate a Huffman code from an array of frequencies" {
var freqs: [19]u16 = [_]u16{
8, // 0
1, // 1
1, // 2
2, // 3
5, // 4
10, // 5
9, // 6
1, // 7
0, // 8
0, // 9
0, // 10
0, // 11
0, // 12
0, // 13
0, // 14
0, // 15
1, // 16
3, // 17
5, // 18
};
var enc = huffmanEncoder(19);
enc.generate(freqs[0..], 7);
try testing.expectEqual(@as(u32, 141), enc.bitLength(freqs[0..]));
try testing.expectEqual(@as(usize, 3), enc.codes[0].len);
try testing.expectEqual(@as(usize, 6), enc.codes[1].len);
try testing.expectEqual(@as(usize, 6), enc.codes[2].len);
try testing.expectEqual(@as(usize, 5), enc.codes[3].len);
try testing.expectEqual(@as(usize, 3), enc.codes[4].len);
try testing.expectEqual(@as(usize, 2), enc.codes[5].len);
try testing.expectEqual(@as(usize, 2), enc.codes[6].len);
try testing.expectEqual(@as(usize, 6), enc.codes[7].len);
try testing.expectEqual(@as(usize, 0), enc.codes[8].len);
try testing.expectEqual(@as(usize, 0), enc.codes[9].len);
try testing.expectEqual(@as(usize, 0), enc.codes[10].len);
try testing.expectEqual(@as(usize, 0), enc.codes[11].len);
try testing.expectEqual(@as(usize, 0), enc.codes[12].len);
try testing.expectEqual(@as(usize, 0), enc.codes[13].len);
try testing.expectEqual(@as(usize, 0), enc.codes[14].len);
try testing.expectEqual(@as(usize, 0), enc.codes[15].len);
try testing.expectEqual(@as(usize, 6), enc.codes[16].len);
try testing.expectEqual(@as(usize, 5), enc.codes[17].len);
try testing.expectEqual(@as(usize, 3), enc.codes[18].len);
try testing.expectEqual(@as(u16, 0x0), enc.codes[5].code);
try testing.expectEqual(@as(u16, 0x2), enc.codes[6].code);
try testing.expectEqual(@as(u16, 0x1), enc.codes[0].code);
try testing.expectEqual(@as(u16, 0x5), enc.codes[4].code);
try testing.expectEqual(@as(u16, 0x3), enc.codes[18].code);
try testing.expectEqual(@as(u16, 0x7), enc.codes[3].code);
try testing.expectEqual(@as(u16, 0x17), enc.codes[17].code);
try testing.expectEqual(@as(u16, 0x0f), enc.codes[1].code);
try testing.expectEqual(@as(u16, 0x2f), enc.codes[2].code);
try testing.expectEqual(@as(u16, 0x1f), enc.codes[7].code);
try testing.expectEqual(@as(u16, 0x3f), enc.codes[16].code);
}
test "flate.HuffmanEncoder generate a Huffman code for the fixed literal table specific to Deflate" {
const enc = fixedLiteralEncoder();
for (enc.codes) |c| {
switch (c.len) {
7 => {
const v = @bitReverse(@as(u7, @intCast(c.code)));
try testing.expect(v <= 0b0010111);
},
8 => {
const v = @bitReverse(@as(u8, @intCast(c.code)));
try testing.expect((v >= 0b000110000 and v <= 0b10111111) or
(v >= 0b11000000 and v <= 11000111));
},
9 => {
const v = @bitReverse(@as(u9, @intCast(c.code)));
try testing.expect(v >= 0b110010000 and v <= 0b111111111);
},
else => unreachable,
}
}
}
test "flate.HuffmanEncoder generate a Huffman code for the 30 possible relative distances (LZ77 distances) of Deflate" {
const enc = fixedDistanceEncoder();
for (enc.codes) |c| {
const v = @bitReverse(@as(u5, @intCast(c.code)));
try testing.expect(v <= 29);
try testing.expect(c.len == 5);
}
}
// Reverse bit-by-bit a N-bit code.
fn bitReverse(comptime T: type, value: T, n: usize) T {
const r = @bitReverse(value);
return r >> @as(math.Log2Int(T), @intCast(@typeInfo(T).Int.bits - n));
}
test "flate bitReverse" {
const ReverseBitsTest = struct {
in: u16,
bit_count: u5,
out: u16,
};
const reverse_bits_tests = [_]ReverseBitsTest{
.{ .in = 1, .bit_count = 1, .out = 1 },
.{ .in = 1, .bit_count = 2, .out = 2 },
.{ .in = 1, .bit_count = 3, .out = 4 },
.{ .in = 1, .bit_count = 4, .out = 8 },
.{ .in = 1, .bit_count = 5, .out = 16 },
.{ .in = 17, .bit_count = 5, .out = 17 },
.{ .in = 257, .bit_count = 9, .out = 257 },
.{ .in = 29, .bit_count = 5, .out = 23 },
};
for (reverse_bits_tests) |h| {
const v = bitReverse(u16, h.in, h.bit_count);
try std.testing.expectEqual(h.out, v);
}
}
test "flate.HuffmanEncoder fixedLiteralEncoder codes" {
var al = std.ArrayList(u8).init(testing.allocator);
defer al.deinit();
var bw = std.io.bitWriter(.little, al.writer());
const f = fixedLiteralEncoder();
for (f.codes) |c| {
try bw.writeBits(c.code, c.len);
}
try testing.expectEqualSlices(u8, &fixed_codes, al.items);
}
pub const fixed_codes = [_]u8{
0b00001100, 0b10001100, 0b01001100, 0b11001100, 0b00101100, 0b10101100, 0b01101100, 0b11101100,
0b00011100, 0b10011100, 0b01011100, 0b11011100, 0b00111100, 0b10111100, 0b01111100, 0b11111100,
0b00000010, 0b10000010, 0b01000010, 0b11000010, 0b00100010, 0b10100010, 0b01100010, 0b11100010,
0b00010010, 0b10010010, 0b01010010, 0b11010010, 0b00110010, 0b10110010, 0b01110010, 0b11110010,
0b00001010, 0b10001010, 0b01001010, 0b11001010, 0b00101010, 0b10101010, 0b01101010, 0b11101010,
0b00011010, 0b10011010, 0b01011010, 0b11011010, 0b00111010, 0b10111010, 0b01111010, 0b11111010,
0b00000110, 0b10000110, 0b01000110, 0b11000110, 0b00100110, 0b10100110, 0b01100110, 0b11100110,
0b00010110, 0b10010110, 0b01010110, 0b11010110, 0b00110110, 0b10110110, 0b01110110, 0b11110110,
0b00001110, 0b10001110, 0b01001110, 0b11001110, 0b00101110, 0b10101110, 0b01101110, 0b11101110,
0b00011110, 0b10011110, 0b01011110, 0b11011110, 0b00111110, 0b10111110, 0b01111110, 0b11111110,
0b00000001, 0b10000001, 0b01000001, 0b11000001, 0b00100001, 0b10100001, 0b01100001, 0b11100001,
0b00010001, 0b10010001, 0b01010001, 0b11010001, 0b00110001, 0b10110001, 0b01110001, 0b11110001,
0b00001001, 0b10001001, 0b01001001, 0b11001001, 0b00101001, 0b10101001, 0b01101001, 0b11101001,
0b00011001, 0b10011001, 0b01011001, 0b11011001, 0b00111001, 0b10111001, 0b01111001, 0b11111001,
0b00000101, 0b10000101, 0b01000101, 0b11000101, 0b00100101, 0b10100101, 0b01100101, 0b11100101,
0b00010101, 0b10010101, 0b01010101, 0b11010101, 0b00110101, 0b10110101, 0b01110101, 0b11110101,
0b00001101, 0b10001101, 0b01001101, 0b11001101, 0b00101101, 0b10101101, 0b01101101, 0b11101101,
0b00011101, 0b10011101, 0b01011101, 0b11011101, 0b00111101, 0b10111101, 0b01111101, 0b11111101,
0b00010011, 0b00100110, 0b01001110, 0b10011010, 0b00111100, 0b01100101, 0b11101010, 0b10110100,
0b11101001, 0b00110011, 0b01100110, 0b11001110, 0b10011010, 0b00111101, 0b01100111, 0b11101110,
0b10111100, 0b11111001, 0b00001011, 0b00010110, 0b00101110, 0b01011010, 0b10111100, 0b01100100,
0b11101001, 0b10110010, 0b11100101, 0b00101011, 0b01010110, 0b10101110, 0b01011010, 0b10111101,
0b01100110, 0b11101101, 0b10111010, 0b11110101, 0b00011011, 0b00110110, 0b01101110, 0b11011010,
0b10111100, 0b01100101, 0b11101011, 0b10110110, 0b11101101, 0b00111011, 0b01110110, 0b11101110,
0b11011010, 0b10111101, 0b01100111, 0b11101111, 0b10111110, 0b11111101, 0b00000111, 0b00001110,
0b00011110, 0b00111010, 0b01111100, 0b11100100, 0b11101000, 0b10110001, 0b11100011, 0b00100111,
0b01001110, 0b10011110, 0b00111010, 0b01111101, 0b11100110, 0b11101100, 0b10111001, 0b11110011,
0b00010111, 0b00101110, 0b01011110, 0b10111010, 0b01111100, 0b11100101, 0b11101010, 0b10110101,
0b11101011, 0b00110111, 0b01101110, 0b11011110, 0b10111010, 0b01111101, 0b11100111, 0b11101110,
0b10111101, 0b11111011, 0b00001111, 0b00011110, 0b00111110, 0b01111010, 0b11111100, 0b11100100,
0b11101001, 0b10110011, 0b11100111, 0b00101111, 0b01011110, 0b10111110, 0b01111010, 0b11111101,
0b11100110, 0b11101101, 0b10111011, 0b11110111, 0b00011111, 0b00111110, 0b01111110, 0b11111010,
0b11111100, 0b11100101, 0b11101011, 0b10110111, 0b11101111, 0b00111111, 0b01111110, 0b11111110,
0b11111010, 0b11111101, 0b11100111, 0b11101111, 0b10111111, 0b11111111, 0b00000000, 0b00100000,
0b00001000, 0b00001100, 0b10000001, 0b11000010, 0b11100000, 0b00001000, 0b00100100, 0b00001010,
0b10001101, 0b11000001, 0b11100010, 0b11110000, 0b00000100, 0b00100010, 0b10001001, 0b01001100,
0b10100001, 0b11010010, 0b11101000, 0b00000011, 0b10000011, 0b01000011, 0b11000011, 0b00100011,
0b10100011,
};

529
lib/std/compress/flate/inflate.zig Normal file
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const std = @import("std");
const assert = std.debug.assert;
const testing = std.testing;
const hfd = @import("huffman_decoder.zig");
const BitReader = @import("bit_reader.zig").BitReader;
const CircularBuffer = @import("CircularBuffer.zig");
const Container = @import("container.zig").Container;
const Token = @import("Token.zig");
const codegen_order = @import("consts.zig").huffman.codegen_order;
/// Decompresses deflate bit stream `reader` and writes uncompressed data to the
/// `writer` stream.
pub fn decompress(comptime container: Container, reader: anytype, writer: anytype) !void {
var d = decompressor(container, reader);
try d.decompress(writer);
}
/// Inflate decompressor for the reader type.
pub fn decompressor(comptime container: Container, reader: anytype) Inflate(container, @TypeOf(reader)) {
return Inflate(container, @TypeOf(reader)).init(reader);
}
/// Inflate decompresses deflate bit stream. Reads compressed data from reader
/// provided in init. Decompressed data are stored in internal hist buffer and
/// can be accesses iterable `next` or reader interface.
///
/// Container defines header/footer wrapper around deflate bit stream. Can be
/// gzip or zlib.
///
/// Deflate bit stream consists of multiple blocks. Block can be one of three types:
/// * stored, non compressed, max 64k in size
/// * fixed, huffman codes are predefined
/// * dynamic, huffman code tables are encoded at the block start
///
/// `step` function runs decoder until internal `hist` buffer is full. Client
/// than needs to read that data in order to proceed with decoding.
///
/// Allocates 74.5K of internal buffers, most important are:
/// * 64K for history (CircularBuffer)
/// * ~10K huffman decoders (Literal and DistanceDecoder)
///
pub fn Inflate(comptime container: Container, comptime ReaderType: type) type {
return struct {
const BitReaderType = BitReader(ReaderType);
const F = BitReaderType.flag;
bits: BitReaderType = .{},
hist: CircularBuffer = .{},
// Hashes, produces checkusm, of uncompressed data for gzip/zlib footer.
hasher: container.Hasher() = .{},
// dynamic block huffman code decoders
lit_dec: hfd.LiteralDecoder = .{}, // literals
dst_dec: hfd.DistanceDecoder = .{}, // distances
// current read state
bfinal: u1 = 0,
block_type: u2 = 0b11,
state: ReadState = .protocol_header,
const ReadState = enum {
protocol_header,
block_header,
block,
protocol_footer,
end,
};
const Self = @This();
pub const Error = BitReaderType.Error || Container.Error || hfd.Error || error{
InvalidCode,
InvalidMatch,
InvalidBlockType,
WrongStoredBlockNlen,
InvalidDynamicBlockHeader,
};
pub fn init(rt: ReaderType) Self {
return .{ .bits = BitReaderType.init(rt) };
}
fn blockHeader(self: *Self) !void {
self.bfinal = try self.bits.read(u1);
self.block_type = try self.bits.read(u2);
}
fn storedBlock(self: *Self) !bool {
self.bits.alignToByte(); // skip padding until byte boundary
// everyting after this is byte aligned in stored block
var len = try self.bits.read(u16);
const nlen = try self.bits.read(u16);
if (len != ~nlen) return error.WrongStoredBlockNlen;
while (len > 0) {
const buf = self.hist.getWritable(len);
try self.bits.readAll(buf);
len -= @intCast(buf.len);
}
return true;
}
fn fixedBlock(self: *Self) !bool {
while (!self.hist.full()) {
const code = try self.bits.readFixedCode();
switch (code) {
0...255 => self.hist.write(@intCast(code)),
256 => return true, // end of block
257...285 => try self.fixedDistanceCode(@intCast(code - 257)),
else => return error.InvalidCode,
}
}
return false;
}
// Handles fixed block non literal (length) code.
// Length code is followed by 5 bits of distance code.
fn fixedDistanceCode(self: *Self, code: u8) !void {
try self.bits.fill(5 + 5 + 13);
const length = try self.decodeLength(code);
const distance = try self.decodeDistance(try self.bits.readF(u5, F.buffered | F.reverse));
try self.hist.writeMatch(length, distance);
}
inline fn decodeLength(self: *Self, code: u8) !u16 {
if (code > 28) return error.InvalidCode;
const ml = Token.matchLength(code);
return if (ml.extra_bits == 0) // 0 - 5 extra bits
ml.base
else
ml.base + try self.bits.readN(ml.extra_bits, F.buffered);
}
fn decodeDistance(self: *Self, code: u8) !u16 {
if (code > 29) return error.InvalidCode;
const md = Token.matchDistance(code);
return if (md.extra_bits == 0) // 0 - 13 extra bits
md.base
else
md.base + try self.bits.readN(md.extra_bits, F.buffered);
}
fn dynamicBlockHeader(self: *Self) !void {
const hlit: u16 = @as(u16, try self.bits.read(u5)) + 257; // number of ll code entries present - 257
const hdist: u16 = @as(u16, try self.bits.read(u5)) + 1; // number of distance code entries - 1
const hclen: u8 = @as(u8, try self.bits.read(u4)) + 4; // hclen + 4 code lenths are encoded
if (hlit > 286 or hdist > 30)
return error.InvalidDynamicBlockHeader;
// lengths for code lengths
var cl_lens = [_]u4{0} ** 19;
for (0..hclen) |i| {
cl_lens[codegen_order[i]] = try self.bits.read(u3);
}
var cl_dec: hfd.CodegenDecoder = .{};
try cl_dec.generate(&cl_lens);
// literal code lengths
var lit_lens = [_]u4{0} ** (286);
var pos: usize = 0;
while (pos < hlit) {
const sym = try cl_dec.find(try self.bits.peekF(u7, F.reverse));
try self.bits.shift(sym.code_bits);
pos += try self.dynamicCodeLength(sym.symbol, &lit_lens, pos);
}
if (pos > hlit)
return error.InvalidDynamicBlockHeader;
// distance code lenths
var dst_lens = [_]u4{0} ** (30);
pos = 0;
while (pos < hdist) {
const sym = try cl_dec.find(try self.bits.peekF(u7, F.reverse));
try self.bits.shift(sym.code_bits);
pos += try self.dynamicCodeLength(sym.symbol, &dst_lens, pos);
}
if (pos > hdist)
return error.InvalidDynamicBlockHeader;
try self.lit_dec.generate(&lit_lens);
try self.dst_dec.generate(&dst_lens);
}
// Decode code length symbol to code length. Writes decoded length into
// lens slice starting at position pos. Returns number of positions
// advanced.
fn dynamicCodeLength(self: *Self, code: u16, lens: []u4, pos: usize) !usize {
if (pos >= lens.len)
return error.InvalidDynamicBlockHeader;
switch (code) {
0...15 => {
// Represent code lengths of 0 - 15
lens[pos] = @intCast(code);
return 1;
},
16 => {
// Copy the previous code length 3 - 6 times.
// The next 2 bits indicate repeat length
const n: u8 = @as(u8, try self.bits.read(u2)) + 3;
if (pos == 0 or pos + n > lens.len)
return error.InvalidDynamicBlockHeader;
for (0..n) |i| {
lens[pos + i] = lens[pos + i - 1];
}
return n;
},
// Repeat a code length of 0 for 3 - 10 times. (3 bits of length)
17 => return @as(u8, try self.bits.read(u3)) + 3,
// Repeat a code length of 0 for 11 - 138 times (7 bits of length)
18 => return @as(u8, try self.bits.read(u7)) + 11,
else => return error.InvalidDynamicBlockHeader,
}
}
// In larger archives most blocks are usually dynamic, so decompression
// performance depends on this function.
fn dynamicBlock(self: *Self) !bool {
// Hot path loop!
while (!self.hist.full()) {
try self.bits.fill(15); // optimization so other bit reads can be buffered (avoiding one `if` in hot path)
const sym = try self.decodeSymbol(&self.lit_dec);
switch (sym.kind) {
.literal => self.hist.write(sym.symbol),
.match => { // Decode match backreference <length, distance>
try self.bits.fill(5 + 15 + 13); // so we can use buffered reads
const length = try self.decodeLength(sym.symbol);
const dsm = try self.decodeSymbol(&self.dst_dec);
const distance = try self.decodeDistance(dsm.symbol);
try self.hist.writeMatch(length, distance);
},
.end_of_block => return true,
}
}
return false;
}
// Peek 15 bits from bits reader (maximum code len is 15 bits). Use
// decoder to find symbol for that code. We then know how many bits is
// used. Shift bit reader for that much bits, those bits are used. And
// return symbol.
fn decodeSymbol(self: *Self, decoder: anytype) !hfd.Symbol {
const sym = try decoder.find(try self.bits.peekF(u15, F.buffered | F.reverse));
try self.bits.shift(sym.code_bits);
return sym;
}
fn step(self: *Self) !void {
switch (self.state) {
.protocol_header => {
try container.parseHeader(&self.bits);
self.state = .block_header;
},
.block_header => {
try self.blockHeader();
self.state = .block;
if (self.block_type == 2) try self.dynamicBlockHeader();
},
.block => {
const done = switch (self.block_type) {
0 => try self.storedBlock(),
1 => try self.fixedBlock(),
2 => try self.dynamicBlock(),
else => return error.InvalidBlockType,
};
if (done) {
self.state = if (self.bfinal == 1) .protocol_footer else .block_header;
}
},
.protocol_footer => {
self.bits.alignToByte();
try container.parseFooter(&self.hasher, &self.bits);
self.state = .end;
},
.end => {},
}
}
/// Replaces the inner reader with new reader.
pub fn setReader(self: *Self, new_reader: ReaderType) void {
self.bits.forward_reader = new_reader;
if (self.state == .end or self.state == .protocol_footer) {
self.state = .protocol_header;
}
}
// Reads all compressed data from the internal reader and outputs plain
// (uncompressed) data to the provided writer.
pub fn decompress(self: *Self, writer: anytype) !void {
while (try self.next()) |buf| {
try writer.writeAll(buf);
}
}
// Iterator interface
/// Can be used in iterator like loop without memcpy to another buffer:
/// while (try inflate.next()) |buf| { ... }
pub fn next(self: *Self) Error!?[]const u8 {
const out = try self.get(0);
if (out.len == 0) return null;
return out;
}
/// Returns decompressed data from internal sliding window buffer.
/// Returned buffer can be any length between 0 and `limit` bytes. 0
/// returned bytes means end of stream reached. With limit=0 returns as
/// much data it can. It newer will be more than 65536 bytes, which is
/// size of internal buffer.
pub fn get(self: *Self, limit: usize) Error![]const u8 {
while (true) {
const out = self.hist.readAtMost(limit);
if (out.len > 0) {
self.hasher.update(out);
return out;
}
if (self.state == .end) return out;
try self.step();
}
}
// Reader interface
pub const Reader = std.io.Reader(*Self, Error, read);
/// Returns the number of bytes read. It may be less than buffer.len.
/// If the number of bytes read is 0, it means end of stream.
/// End of stream is not an error condition.
pub fn read(self: *Self, buffer: []u8) Error!usize {
const out = try self.get(buffer.len);
@memcpy(buffer[0..out.len], out);
return out.len;
}
pub fn reader(self: *Self) Reader {
return .{ .context = self };
}
};
}
test "flate.Inflate decompress" {
const cases = [_]struct {
in: []const u8,
out: []const u8,
}{
// non compressed block (type 0)
.{
.in = &[_]u8{
0b0000_0001, 0b0000_1100, 0x00, 0b1111_0011, 0xff, // deflate fixed buffer header len, nlen
'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', 0x0a, // non compressed data
},
.out = "Hello world\n",
},
// fixed code block (type 1)
.{
.in = &[_]u8{
0xf3, 0x48, 0xcd, 0xc9, 0xc9, 0x57, 0x28, 0xcf, // deflate data block type 1
0x2f, 0xca, 0x49, 0xe1, 0x02, 0x00,
},
.out = "Hello world\n",
},
// dynamic block (type 2)
.{
.in = &[_]u8{
0x3d, 0xc6, 0x39, 0x11, 0x00, 0x00, 0x0c, 0x02, // deflate data block type 2
0x30, 0x2b, 0xb5, 0x52, 0x1e, 0xff, 0x96, 0x38,
0x16, 0x96, 0x5c, 0x1e, 0x94, 0xcb, 0x6d, 0x01,
},
.out = "ABCDEABCD ABCDEABCD",
},
};
for (cases) |c| {
var fb = std.io.fixedBufferStream(c.in);
var al = std.ArrayList(u8).init(testing.allocator);
defer al.deinit();
try decompress(.raw, fb.reader(), al.writer());
try testing.expectEqualStrings(c.out, al.items);
}
}
test "flate.Inflate gzip decompress" {
const cases = [_]struct {
in: []const u8,
out: []const u8,
}{
// non compressed block (type 0)
.{
.in = &[_]u8{
0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, // gzip header (10 bytes)
0b0000_0001, 0b0000_1100, 0x00, 0b1111_0011, 0xff, // deflate fixed buffer header len, nlen
'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', 0x0a, // non compressed data
0xd5, 0xe0, 0x39, 0xb7, // gzip footer: checksum
0x0c, 0x00, 0x00, 0x00, // gzip footer: size
},
.out = "Hello world\n",
},
// fixed code block (type 1)
.{
.in = &[_]u8{
0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x03, // gzip header (10 bytes)
0xf3, 0x48, 0xcd, 0xc9, 0xc9, 0x57, 0x28, 0xcf, // deflate data block type 1
0x2f, 0xca, 0x49, 0xe1, 0x02, 0x00,
0xd5, 0xe0, 0x39, 0xb7, 0x0c, 0x00, 0x00, 0x00, // gzip footer (chksum, len)
},
.out = "Hello world\n",
},
// dynamic block (type 2)
.{
.in = &[_]u8{
0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, // gzip header (10 bytes)
0x3d, 0xc6, 0x39, 0x11, 0x00, 0x00, 0x0c, 0x02, // deflate data block type 2
0x30, 0x2b, 0xb5, 0x52, 0x1e, 0xff, 0x96, 0x38,
0x16, 0x96, 0x5c, 0x1e, 0x94, 0xcb, 0x6d, 0x01,
0x17, 0x1c, 0x39, 0xb4, 0x13, 0x00, 0x00, 0x00, // gzip footer (chksum, len)
},
.out = "ABCDEABCD ABCDEABCD",
},
// gzip header with name
.{
.in = &[_]u8{
0x1f, 0x8b, 0x08, 0x08, 0xe5, 0x70, 0xb1, 0x65, 0x00, 0x03, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x2e,
0x74, 0x78, 0x74, 0x00, 0xf3, 0x48, 0xcd, 0xc9, 0xc9, 0x57, 0x28, 0xcf, 0x2f, 0xca, 0x49, 0xe1,
0x02, 0x00, 0xd5, 0xe0, 0x39, 0xb7, 0x0c, 0x00, 0x00, 0x00,
},
.out = "Hello world\n",
},
};
for (cases) |c| {
var fb = std.io.fixedBufferStream(c.in);
var al = std.ArrayList(u8).init(testing.allocator);
defer al.deinit();
try decompress(.gzip, fb.reader(), al.writer());
try testing.expectEqualStrings(c.out, al.items);
}
}
test "flate.Inflate zlib decompress" {
const cases = [_]struct {
in: []const u8,
out: []const u8,
}{
// non compressed block (type 0)
.{
.in = &[_]u8{
0x78, 0b10_0_11100, // zlib header (2 bytes)
0b0000_0001, 0b0000_1100, 0x00, 0b1111_0011, 0xff, // deflate fixed buffer header len, nlen
'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', 0x0a, // non compressed data
0x1c, 0xf2, 0x04, 0x47, // zlib footer: checksum
},
.out = "Hello world\n",
},
};
for (cases) |c| {
var fb = std.io.fixedBufferStream(c.in);
var al = std.ArrayList(u8).init(testing.allocator);
defer al.deinit();
try decompress(.zlib, fb.reader(), al.writer());
try testing.expectEqualStrings(c.out, al.items);
}
}
test "flate.Inflate fuzzing tests" {
const cases = [_]struct {
input: []const u8,
out: []const u8 = "",
err: ?anyerror = null,
}{
.{ .input = "deflate-stream", .out = @embedFile("testdata/fuzz/deflate-stream.expect") }, // 0
.{ .input = "empty-distance-alphabet01" },
.{ .input = "empty-distance-alphabet02" },
.{ .input = "end-of-stream", .err = error.EndOfStream },
.{ .input = "invalid-distance", .err = error.InvalidMatch },
.{ .input = "invalid-tree01", .err = error.IncompleteHuffmanTree }, // 5
.{ .input = "invalid-tree02", .err = error.IncompleteHuffmanTree },
.{ .input = "invalid-tree03", .err = error.IncompleteHuffmanTree },
.{ .input = "lengths-overflow", .err = error.InvalidDynamicBlockHeader },
.{ .input = "out-of-codes", .err = error.InvalidCode },
.{ .input = "puff01", .err = error.WrongStoredBlockNlen }, // 10
.{ .input = "puff02", .err = error.EndOfStream },
.{ .input = "puff03", .out = &[_]u8{0xa} },
.{ .input = "puff04", .err = error.InvalidCode },
.{ .input = "puff05", .err = error.EndOfStream },
.{ .input = "puff06", .err = error.EndOfStream },
.{ .input = "puff08", .err = error.InvalidCode },
.{ .input = "puff09", .out = "P" },
.{ .input = "puff10", .err = error.InvalidCode },
.{ .input = "puff11", .err = error.InvalidMatch },
.{ .input = "puff12", .err = error.InvalidDynamicBlockHeader }, // 20
.{ .input = "puff13", .err = error.IncompleteHuffmanTree },
.{ .input = "puff14", .err = error.EndOfStream },
.{ .input = "puff15", .err = error.IncompleteHuffmanTree },
.{ .input = "puff16", .err = error.InvalidDynamicBlockHeader },
.{ .input = "puff17", .err = error.InvalidDynamicBlockHeader }, // 25
.{ .input = "fuzz1", .err = error.InvalidDynamicBlockHeader },
.{ .input = "fuzz2", .err = error.InvalidDynamicBlockHeader },
.{ .input = "fuzz3", .err = error.InvalidMatch },
.{ .input = "fuzz4", .err = error.OversubscribedHuffmanTree },
.{ .input = "puff18", .err = error.OversubscribedHuffmanTree }, // 30
.{ .input = "puff19", .err = error.OversubscribedHuffmanTree },
.{ .input = "puff20", .err = error.OversubscribedHuffmanTree },
.{ .input = "puff21", .err = error.OversubscribedHuffmanTree },
.{ .input = "puff22", .err = error.OversubscribedHuffmanTree },
.{ .input = "puff23", .err = error.InvalidDynamicBlockHeader }, // 35
.{ .input = "puff24", .err = error.InvalidDynamicBlockHeader },
.{ .input = "puff25", .err = error.OversubscribedHuffmanTree },
.{ .input = "puff26", .err = error.InvalidDynamicBlockHeader },
.{ .input = "puff27", .err = error.InvalidDynamicBlockHeader },
};
inline for (cases, 0..) |c, case_no| {
var in = std.io.fixedBufferStream(@embedFile("testdata/fuzz/" ++ c.input ++ ".input"));
var out = std.ArrayList(u8).init(testing.allocator);
defer out.deinit();
errdefer std.debug.print("test case failed {}\n", .{case_no});
if (c.err) |expected_err| {
try testing.expectError(expected_err, decompress(.raw, in.reader(), out.writer()));
} else {
try decompress(.raw, in.reader(), out.writer());
try testing.expectEqualStrings(c.out, out.items);
}
}
}

606
lib/std/compress/flate/testdata/block_writer.zig vendored Normal file
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@@ -0,0 +1,606 @@
const Token = @import("../Token.zig");
pub const TestCase = struct {
tokens: []const Token,
input: []const u8 = "", // File name of input data matching the tokens.
want: []const u8 = "", // File name of data with the expected output with input available.
want_no_input: []const u8 = "", // File name of the expected output when no input is available.
};
pub const testCases = blk: {
@setEvalBranchQuota(4096 * 2);
const L = Token.initLiteral;
const M = Token.initMatch;
const ml = M(1, 258); // Maximum length token. Used to reduce the size of writeBlockTests
break :blk &[_]TestCase{
TestCase{
.input = "huffman-null-max.input",
.want = "huffman-null-max.{s}.expect",
.want_no_input = "huffman-null-max.{s}.expect-noinput",
.tokens = &[_]Token{
L(0x0), ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, L(0x0), L(0x0),
},
},
TestCase{
.input = "huffman-pi.input",
.want = "huffman-pi.{s}.expect",
.want_no_input = "huffman-pi.{s}.expect-noinput",
.tokens = &[_]Token{
L('3'), L('.'), L('1'), L('4'), L('1'), L('5'), L('9'), L('2'),
L('6'), L('5'), L('3'), L('5'), L('8'), L('9'), L('7'), L('9'),
L('3'), L('2'), L('3'), L('8'), L('4'), L('6'), L('2'), L('6'),
L('4'), L('3'), L('3'), L('8'), L('3'), L('2'), L('7'), L('9'),
L('5'), L('0'), L('2'), L('8'), L('8'), L('4'), L('1'), L('9'),
L('7'), L('1'), L('6'), L('9'), L('3'), L('9'), L('9'), L('3'),
L('7'), L('5'), L('1'), L('0'), L('5'), L('8'), L('2'), L('0'),
L('9'), L('7'), L('4'), L('9'), L('4'), L('4'), L('5'), L('9'),
L('2'), L('3'), L('0'), L('7'), L('8'), L('1'), L('6'), L('4'),
L('0'), L('6'), L('2'), L('8'), L('6'), L('2'), L('0'), L('8'),
L('9'), L('9'), L('8'), L('6'), L('2'), L('8'), L('0'), L('3'),
L('4'), L('8'), L('2'), L('5'), L('3'), L('4'), L('2'), L('1'),
L('1'), L('7'), L('0'), L('6'), L('7'), L('9'), L('8'), L('2'),
L('1'), L('4'), L('8'), L('0'), L('8'), L('6'), L('5'), L('1'),
L('3'), L('2'), L('8'), L('2'), L('3'), L('0'), L('6'), L('6'),
L('4'), L('7'), L('0'), L('9'), L('3'), L('8'), L('4'), L('4'),
L('6'), L('0'), L('9'), L('5'), L('5'), L('0'), L('5'), L('8'),
L('2'), L('2'), L('3'), L('1'), L('7'), L('2'), L('5'), L('3'),
L('5'), L('9'), L('4'), L('0'), L('8'), L('1'), L('2'), L('8'),
L('4'), L('8'), L('1'), L('1'), L('1'), L('7'), L('4'), M(127, 4),
L('4'), L('1'), L('0'), L('2'), L('7'), L('0'), L('1'), L('9'),
L('3'), L('8'), L('5'), L('2'), L('1'), L('1'), L('0'), L('5'),
L('5'), L('5'), L('9'), L('6'), L('4'), L('4'), L('6'), L('2'),
L('2'), L('9'), L('4'), L('8'), L('9'), L('5'), L('4'), L('9'),
L('3'), L('0'), L('3'), L('8'), L('1'), M(19, 4), L('2'), L('8'),
L('8'), L('1'), L('0'), L('9'), L('7'), L('5'), L('6'), L('6'),
L('5'), L('9'), L('3'), L('3'), L('4'), L('4'), L('6'), M(72, 4),
L('7'), L('5'), L('6'), L('4'), L('8'), L('2'), L('3'), L('3'),
L('7'), L('8'), L('6'), L('7'), L('8'), L('3'), L('1'), L('6'),
L('5'), L('2'), L('7'), L('1'), L('2'), L('0'), L('1'), L('9'),
L('0'), L('9'), L('1'), L('4'), M(27, 4), L('5'), L('6'), L('6'),
L('9'), L('2'), L('3'), L('4'), L('6'), M(179, 4), L('6'), L('1'),
L('0'), L('4'), L('5'), L('4'), L('3'), L('2'), L('6'), M(51, 4),
L('1'), L('3'), L('3'), L('9'), L('3'), L('6'), L('0'), L('7'),
L('2'), L('6'), L('0'), L('2'), L('4'), L('9'), L('1'), L('4'),
L('1'), L('2'), L('7'), L('3'), L('7'), L('2'), L('4'), L('5'),
L('8'), L('7'), L('0'), L('0'), L('6'), L('6'), L('0'), L('6'),
L('3'), L('1'), L('5'), L('5'), L('8'), L('8'), L('1'), L('7'),
L('4'), L('8'), L('8'), L('1'), L('5'), L('2'), L('0'), L('9'),
L('2'), L('0'), L('9'), L('6'), L('2'), L('8'), L('2'), L('9'),
L('2'), L('5'), L('4'), L('0'), L('9'), L('1'), L('7'), L('1'),
L('5'), L('3'), L('6'), L('4'), L('3'), L('6'), L('7'), L('8'),
L('9'), L('2'), L('5'), L('9'), L('0'), L('3'), L('6'), L('0'),
L('0'), L('1'), L('1'), L('3'), L('3'), L('0'), L('5'), L('3'),
L('0'), L('5'), L('4'), L('8'), L('8'), L('2'), L('0'), L('4'),
L('6'), L('6'), L('5'), L('2'), L('1'), L('3'), L('8'), L('4'),
L('1'), L('4'), L('6'), L('9'), L('5'), L('1'), L('9'), L('4'),
L('1'), L('5'), L('1'), L('1'), L('6'), L('0'), L('9'), L('4'),
L('3'), L('3'), L('0'), L('5'), L('7'), L('2'), L('7'), L('0'),
L('3'), L('6'), L('5'), L('7'), L('5'), L('9'), L('5'), L('9'),
L('1'), L('9'), L('5'), L('3'), L('0'), L('9'), L('2'), L('1'),
L('8'), L('6'), L('1'), L('1'), L('7'), M(234, 4), L('3'), L('2'),
M(10, 4), L('9'), L('3'), L('1'), L('0'), L('5'), L('1'), L('1'),
L('8'), L('5'), L('4'), L('8'), L('0'), L('7'), M(271, 4), L('3'),
L('7'), L('9'), L('9'), L('6'), L('2'), L('7'), L('4'), L('9'),
L('5'), L('6'), L('7'), L('3'), L('5'), L('1'), L('8'), L('8'),
L('5'), L('7'), L('5'), L('2'), L('7'), L('2'), L('4'), L('8'),
L('9'), L('1'), L('2'), L('2'), L('7'), L('9'), L('3'), L('8'),
L('1'), L('8'), L('3'), L('0'), L('1'), L('1'), L('9'), L('4'),
L('9'), L('1'), L('2'), L('9'), L('8'), L('3'), L('3'), L('6'),
L('7'), L('3'), L('3'), L('6'), L('2'), L('4'), L('4'), L('0'),
L('6'), L('5'), L('6'), L('6'), L('4'), L('3'), L('0'), L('8'),
L('6'), L('0'), L('2'), L('1'), L('3'), L('9'), L('4'), L('9'),
L('4'), L('6'), L('3'), L('9'), L('5'), L('2'), L('2'), L('4'),
L('7'), L('3'), L('7'), L('1'), L('9'), L('0'), L('7'), L('0'),
L('2'), L('1'), L('7'), L('9'), L('8'), M(154, 5), L('7'), L('0'),
L('2'), L('7'), L('7'), L('0'), L('5'), L('3'), L('9'), L('2'),
L('1'), L('7'), L('1'), L('7'), L('6'), L('2'), L('9'), L('3'),
L('1'), L('7'), L('6'), L('7'), L('5'), M(563, 5), L('7'), L('4'),
L('8'), L('1'), M(7, 4), L('6'), L('6'), L('9'), L('4'), L('0'),
M(488, 4), L('0'), L('0'), L('0'), L('5'), L('6'), L('8'), L('1'),
L('2'), L('7'), L('1'), L('4'), L('5'), L('2'), L('6'), L('3'),
L('5'), L('6'), L('0'), L('8'), L('2'), L('7'), L('7'), L('8'),
L('5'), L('7'), L('7'), L('1'), L('3'), L('4'), L('2'), L('7'),
L('5'), L('7'), L('7'), L('8'), L('9'), L('6'), M(298, 4), L('3'),
L('6'), L('3'), L('7'), L('1'), L('7'), L('8'), L('7'), L('2'),
L('1'), L('4'), L('6'), L('8'), L('4'), L('4'), L('0'), L('9'),
L('0'), L('1'), L('2'), L('2'), L('4'), L('9'), L('5'), L('3'),
L('4'), L('3'), L('0'), L('1'), L('4'), L('6'), L('5'), L('4'),
L('9'), L('5'), L('8'), L('5'), L('3'), L('7'), L('1'), L('0'),
L('5'), L('0'), L('7'), L('9'), M(203, 4), L('6'), M(340, 4), L('8'),
L('9'), L('2'), L('3'), L('5'), L('4'), M(458, 4), L('9'), L('5'),
L('6'), L('1'), L('1'), L('2'), L('1'), L('2'), L('9'), L('0'),
L('2'), L('1'), L('9'), L('6'), L('0'), L('8'), L('6'), L('4'),
L('0'), L('3'), L('4'), L('4'), L('1'), L('8'), L('1'), L('5'),
L('9'), L('8'), L('1'), L('3'), L('6'), L('2'), L('9'), L('7'),
L('7'), L('4'), M(117, 4), L('0'), L('9'), L('9'), L('6'), L('0'),
L('5'), L('1'), L('8'), L('7'), L('0'), L('7'), L('2'), L('1'),
L('1'), L('3'), L('4'), L('9'), M(1, 5), L('8'), L('3'), L('7'),
L('2'), L('9'), L('7'), L('8'), L('0'), L('4'), L('9'), L('9'),
M(731, 4), L('9'), L('7'), L('3'), L('1'), L('7'), L('3'), L('2'),
L('8'), M(395, 4), L('6'), L('3'), L('1'), L('8'), L('5'), M(770, 4),
M(745, 4), L('4'), L('5'), L('5'), L('3'), L('4'), L('6'), L('9'),
L('0'), L('8'), L('3'), L('0'), L('2'), L('6'), L('4'), L('2'),
L('5'), L('2'), L('2'), L('3'), L('0'), M(740, 4), M(616, 4), L('8'),
L('5'), L('0'), L('3'), L('5'), L('2'), L('6'), L('1'), L('9'),
L('3'), L('1'), L('1'), M(531, 4), L('1'), L('0'), L('1'), L('0'),
L('0'), L('0'), L('3'), L('1'), L('3'), L('7'), L('8'), L('3'),
L('8'), L('7'), L('5'), L('2'), L('8'), L('8'), L('6'), L('5'),
L('8'), L('7'), L('5'), L('3'), L('3'), L('2'), L('0'), L('8'),
L('3'), L('8'), L('1'), L('4'), L('2'), L('0'), L('6'), M(321, 4),
M(300, 4), L('1'), L('4'), L('7'), L('3'), L('0'), L('3'), L('5'),
L('9'), M(815, 5), L('9'), L('0'), L('4'), L('2'), L('8'), L('7'),
L('5'), L('5'), L('4'), L('6'), L('8'), L('7'), L('3'), L('1'),
L('1'), L('5'), L('9'), L('5'), M(854, 4), L('3'), L('8'), L('8'),
L('2'), L('3'), L('5'), L('3'), L('7'), L('8'), L('7'), L('5'),
M(896, 5), L('9'), M(315, 4), L('1'), M(329, 4), L('8'), L('0'), L('5'),
L('3'), M(395, 4), L('2'), L('2'), L('6'), L('8'), L('0'), L('6'),
L('6'), L('1'), L('3'), L('0'), L('0'), L('1'), L('9'), L('2'),
L('7'), L('8'), L('7'), L('6'), L('6'), L('1'), L('1'), L('1'),
L('9'), L('5'), L('9'), M(568, 4), L('6'), M(293, 5), L('8'), L('9'),
L('3'), L('8'), L('0'), L('9'), L('5'), L('2'), L('5'), L('7'),
L('2'), L('0'), L('1'), L('0'), L('6'), L('5'), L('4'), L('8'),
L('5'), L('8'), L('6'), L('3'), L('2'), L('7'), M(155, 4), L('9'),
L('3'), L('6'), L('1'), L('5'), L('3'), M(545, 4), M(349, 5), L('2'),
L('3'), L('0'), L('3'), L('0'), L('1'), L('9'), L('5'), L('2'),
L('0'), L('3'), L('5'), L('3'), L('0'), L('1'), L('8'), L('5'),
L('2'), M(370, 4), M(118, 4), L('3'), L('6'), L('2'), L('2'), L('5'),
L('9'), L('9'), L('4'), L('1'), L('3'), M(597, 4), L('4'), L('9'),
L('7'), L('2'), L('1'), L('7'), M(223, 4), L('3'), L('4'), L('7'),
L('9'), L('1'), L('3'), L('1'), L('5'), L('1'), L('5'), L('5'),
L('7'), L('4'), L('8'), L('5'), L('7'), L('2'), L('4'), L('2'),
L('4'), L('5'), L('4'), L('1'), L('5'), L('0'), L('6'), L('9'),
M(320, 4), L('8'), L('2'), L('9'), L('5'), L('3'), L('3'), L('1'),
L('1'), L('6'), L('8'), L('6'), L('1'), L('7'), L('2'), L('7'),
L('8'), M(824, 4), L('9'), L('0'), L('7'), L('5'), L('0'), L('9'),
M(270, 4), L('7'), L('5'), L('4'), L('6'), L('3'), L('7'), L('4'),
L('6'), L('4'), L('9'), L('3'), L('9'), L('3'), L('1'), L('9'),
L('2'), L('5'), L('5'), L('0'), L('6'), L('0'), L('4'), L('0'),
L('0'), L('9'), M(620, 4), L('1'), L('6'), L('7'), L('1'), L('1'),
L('3'), L('9'), L('0'), L('0'), L('9'), L('8'), M(822, 4), L('4'),
L('0'), L('1'), L('2'), L('8'), L('5'), L('8'), L('3'), L('6'),
L('1'), L('6'), L('0'), L('3'), L('5'), L('6'), L('3'), L('7'),
L('0'), L('7'), L('6'), L('6'), L('0'), L('1'), L('0'), L('4'),
M(371, 4), L('8'), L('1'), L('9'), L('4'), L('2'), L('9'), M(1055, 5),
M(240, 4), M(652, 4), L('7'), L('8'), L('3'), L('7'), L('4'), M(1193, 4),
L('8'), L('2'), L('5'), L('5'), L('3'), L('7'), M(522, 5), L('2'),
L('6'), L('8'), M(47, 4), L('4'), L('0'), L('4'), L('7'), M(466, 4),
L('4'), M(1206, 4), M(910, 4), L('8'), L('4'), M(937, 4), L('6'), M(800, 6),
L('3'), L('3'), L('1'), L('3'), L('6'), L('7'), L('7'), L('0'),
L('2'), L('8'), L('9'), L('8'), L('9'), L('1'), L('5'), L('2'),
M(99, 4), L('5'), L('2'), L('1'), L('6'), L('2'), L('0'), L('5'),
L('6'), L('9'), L('6'), M(1042, 4), L('0'), L('5'), L('8'), M(1144, 4),
L('5'), M(1177, 4), L('5'), L('1'), L('1'), M(522, 4), L('8'), L('2'),
L('4'), L('3'), L('0'), L('0'), L('3'), L('5'), L('5'), L('8'),
L('7'), L('6'), L('4'), L('0'), L('2'), L('4'), L('7'), L('4'),
L('9'), L('6'), L('4'), L('7'), L('3'), L('2'), L('6'), L('3'),
M(1087, 4), L('9'), L('9'), L('2'), M(1100, 4), L('4'), L('2'), L('6'),
L('9'), M(710, 6), L('7'), M(471, 4), L('4'), M(1342, 4), M(1054, 4), L('9'),
L('3'), L('4'), L('1'), L('7'), M(430, 4), L('1'), L('2'), M(43, 4),
L('4'), M(415, 4), L('1'), L('5'), L('0'), L('3'), L('0'), L('2'),
L('8'), L('6'), L('1'), L('8'), L('2'), L('9'), L('7'), L('4'),
L('5'), L('5'), L('5'), L('7'), L('0'), L('6'), L('7'), L('4'),
M(310, 4), L('5'), L('0'), L('5'), L('4'), L('9'), L('4'), L('5'),
L('8'), M(454, 4), L('9'), M(82, 4), L('5'), L('6'), M(493, 4), L('7'),
L('2'), L('1'), L('0'), L('7'), L('9'), M(346, 4), L('3'), L('0'),
M(267, 4), L('3'), L('2'), L('1'), L('1'), L('6'), L('5'), L('3'),
L('4'), L('4'), L('9'), L('8'), L('7'), L('2'), L('0'), L('2'),
L('7'), M(284, 4), L('0'), L('2'), L('3'), L('6'), L('4'), M(559, 4),
L('5'), L('4'), L('9'), L('9'), L('1'), L('1'), L('9'), L('8'),
M(1049, 4), L('4'), M(284, 4), L('5'), L('3'), L('5'), L('6'), L('6'),
L('3'), L('6'), L('9'), M(1105, 4), L('2'), L('6'), L('5'), M(741, 4),
L('7'), L('8'), L('6'), L('2'), L('5'), L('5'), L('1'), M(987, 4),
L('1'), L('7'), L('5'), L('7'), L('4'), L('6'), L('7'), L('2'),
L('8'), L('9'), L('0'), L('9'), L('7'), L('7'), L('7'), L('7'),
M(1108, 5), L('0'), L('0'), L('0'), M(1534, 4), L('7'), L('0'), M(1248, 4),
L('6'), M(1002, 4), L('4'), L('9'), L('1'), M(1055, 4), M(664, 4), L('2'),
L('1'), L('4'), L('7'), L('7'), L('2'), L('3'), L('5'), L('0'),
L('1'), L('4'), L('1'), L('4'), M(1604, 4), L('3'), L('5'), L('6'),
M(1200, 4), L('1'), L('6'), L('1'), L('3'), L('6'), L('1'), L('1'),
L('5'), L('7'), L('3'), L('5'), L('2'), L('5'), M(1285, 4), L('3'),
L('4'), M(92, 4), L('1'), L('8'), M(1148, 4), L('8'), L('4'), M(1512, 4),
L('3'), L('3'), L('2'), L('3'), L('9'), L('0'), L('7'), L('3'),
L('9'), L('4'), L('1'), L('4'), L('3'), L('3'), L('3'), L('4'),
L('5'), L('4'), L('7'), L('7'), L('6'), L('2'), L('4'), M(579, 4),
L('2'), L('5'), L('1'), L('8'), L('9'), L('8'), L('3'), L('5'),
L('6'), L('9'), L('4'), L('8'), L('5'), L('5'), L('6'), L('2'),
L('0'), L('9'), L('9'), L('2'), L('1'), L('9'), L('2'), L('2'),
L('2'), L('1'), L('8'), L('4'), L('2'), L('7'), M(575, 4), L('2'),
M(187, 4), L('6'), L('8'), L('8'), L('7'), L('6'), L('7'), L('1'),
L('7'), L('9'), L('0'), M(86, 4), L('0'), M(263, 5), L('6'), L('6'),
M(1000, 4), L('8'), L('8'), L('6'), L('2'), L('7'), L('2'), M(1757, 4),
L('1'), L('7'), L('8'), L('6'), L('0'), L('8'), L('5'), L('7'),
M(116, 4), L('3'), M(765, 5), L('7'), L('9'), L('7'), L('6'), L('6'),
L('8'), L('1'), M(702, 4), L('0'), L('0'), L('9'), L('5'), L('3'),
L('8'), L('8'), M(1593, 4), L('3'), M(1702, 4), L('0'), L('6'), L('8'),
L('0'), L('0'), L('6'), L('4'), L('2'), L('2'), L('5'), L('1'),
L('2'), L('5'), L('2'), M(1404, 4), L('7'), L('3'), L('9'), L('2'),
M(664, 4), M(1141, 4), L('4'), M(1716, 5), L('8'), L('6'), L('2'), L('6'),
L('9'), L('4'), L('5'), M(486, 4), L('4'), L('1'), L('9'), L('6'),
L('5'), L('2'), L('8'), L('5'), L('0'), M(154, 4), M(925, 4), L('1'),
L('8'), L('6'), L('3'), M(447, 4), L('4'), M(341, 5), L('2'), L('0'),
L('3'), L('9'), M(1420, 4), L('4'), L('5'), M(701, 4), L('2'), L('3'),
L('7'), M(1069, 4), L('6'), M(1297, 4), L('5'), L('6'), M(1593, 4), L('7'),
L('1'), L('9'), L('1'), L('7'), L('2'), L('8'), M(370, 4), L('7'),
L('6'), L('4'), L('6'), L('5'), L('7'), L('5'), L('7'), L('3'),
L('9'), M(258, 4), L('3'), L('8'), L('9'), M(1865, 4), L('8'), L('3'),
L('2'), L('6'), L('4'), L('5'), L('9'), L('9'), L('5'), L('8'),
M(1704, 4), L('0'), L('4'), L('7'), L('8'), M(479, 4), M(809, 4), L('9'),
M(46, 4), L('6'), L('4'), L('0'), L('7'), L('8'), L('9'), L('5'),
L('1'), M(143, 4), L('6'), L('8'), L('3'), M(304, 4), L('2'), L('5'),
L('9'), L('5'), L('7'), L('0'), M(1129, 4), L('8'), L('2'), L('2'),
M(713, 4), L('2'), M(1564, 4), L('4'), L('0'), L('7'), L('7'), L('2'),
L('6'), L('7'), L('1'), L('9'), L('4'), L('7'), L('8'), M(794, 4),
L('8'), L('2'), L('6'), L('0'), L('1'), L('4'), L('7'), L('6'),
L('9'), L('9'), L('0'), L('9'), M(1257, 4), L('0'), L('1'), L('3'),
L('6'), L('3'), L('9'), L('4'), L('4'), L('3'), M(640, 4), L('3'),
L('0'), M(262, 4), L('2'), L('0'), L('3'), L('4'), L('9'), L('6'),
L('2'), L('5'), L('2'), L('4'), L('5'), L('1'), L('7'), M(950, 4),
L('9'), L('6'), L('5'), L('1'), L('4'), L('3'), L('1'), L('4'),
L('2'), L('9'), L('8'), L('0'), L('9'), L('1'), L('9'), L('0'),
L('6'), L('5'), L('9'), L('2'), M(643, 4), L('7'), L('2'), L('2'),
L('1'), L('6'), L('9'), L('6'), L('4'), L('6'), M(1050, 4), M(123, 4),
L('5'), M(1295, 4), L('4'), M(1382, 5), L('8'), M(1370, 4), L('9'), L('7'),
M(1404, 4), L('5'), L('4'), M(1182, 4), M(575, 4), L('7'), M(1627, 4), L('8'),
L('4'), L('6'), L('8'), L('1'), L('3'), M(141, 4), L('6'), L('8'),
L('3'), L('8'), L('6'), L('8'), L('9'), L('4'), L('2'), L('7'),
L('7'), L('4'), L('1'), L('5'), L('5'), L('9'), L('9'), L('1'),
L('8'), L('5'), M(91, 4), L('2'), L('4'), L('5'), L('9'), L('5'),
L('3'), L('9'), L('5'), L('9'), L('4'), L('3'), L('1'), M(1464, 4),
L('7'), M(19, 4), L('6'), L('8'), L('0'), L('8'), L('4'), L('5'),
M(744, 4), L('7'), L('3'), M(2079, 4), L('9'), L('5'), L('8'), L('4'),
L('8'), L('6'), L('5'), L('3'), L('8'), M(1769, 4), L('6'), L('2'),
M(243, 4), L('6'), L('0'), L('9'), M(1207, 4), L('6'), L('0'), L('8'),
L('0'), L('5'), L('1'), L('2'), L('4'), L('3'), L('8'), L('8'),
L('4'), M(315, 4), M(12, 4), L('4'), L('1'), L('3'), M(784, 4), L('7'),
L('6'), L('2'), L('7'), L('8'), M(834, 4), L('7'), L('1'), L('5'),
M(1436, 4), L('3'), L('5'), L('9'), L('9'), L('7'), L('7'), L('0'),
L('0'), L('1'), L('2'), L('9'), M(1139, 4), L('8'), L('9'), L('4'),
L('4'), L('1'), M(632, 4), L('6'), L('8'), L('5'), L('5'), M(96, 4),
L('4'), L('0'), L('6'), L('3'), M(2279, 4), L('2'), L('0'), L('7'),
L('2'), L('2'), M(345, 4), M(516, 5), L('4'), L('8'), L('1'), L('5'),
L('8'), M(518, 4), M(511, 4), M(635, 4), M(665, 4), L('3'), L('9'), L('4'),
L('5'), L('2'), L('2'), L('6'), L('7'), M(1175, 6), L('8'), M(1419, 4),
L('2'), L('1'), M(747, 4), L('2'), M(904, 4), L('5'), L('4'), L('6'),
L('6'), L('6'), M(1308, 4), L('2'), L('3'), L('9'), L('8'), L('6'),
L('4'), L('5'), L('6'), M(1221, 4), L('1'), L('6'), L('3'), L('5'),
M(596, 5), M(2066, 4), L('7'), M(2222, 4), L('9'), L('8'), M(1119, 4), L('9'),
L('3'), L('6'), L('3'), L('4'), M(1884, 4), L('7'), L('4'), L('3'),
L('2'), L('4'), M(1148, 4), L('1'), L('5'), L('0'), L('7'), L('6'),
M(1212, 4), L('7'), L('9'), L('4'), L('5'), L('1'), L('0'), L('9'),
M(63, 4), L('0'), L('9'), L('4'), L('0'), M(1703, 4), L('8'), L('8'),
L('7'), L('9'), L('7'), L('1'), L('0'), L('8'), L('9'), L('3'),
M(2289, 4), L('6'), L('9'), L('1'), L('3'), L('6'), L('8'), L('6'),
L('7'), L('2'), M(604, 4), M(511, 4), L('5'), M(1344, 4), M(1129, 4), M(2050, 4),
L('1'), L('7'), L('9'), L('2'), L('8'), L('6'), L('8'), M(2253, 4),
L('8'), L('7'), L('4'), L('7'), M(1951, 5), L('8'), L('2'), L('4'),
M(2427, 4), L('8'), M(604, 4), L('7'), L('1'), L('4'), L('9'), L('0'),
L('9'), L('6'), L('7'), L('5'), L('9'), L('8'), M(1776, 4), L('3'),
L('6'), L('5'), M(309, 4), L('8'), L('1'), M(93, 4), M(1862, 4), M(2359, 4),
L('6'), L('8'), L('2'), L('9'), M(1407, 4), L('8'), L('7'), L('2'),
L('2'), L('6'), L('5'), L('8'), L('8'), L('0'), M(1554, 4), L('5'),
M(586, 4), L('4'), L('2'), L('7'), L('0'), L('4'), L('7'), L('7'),
L('5'), L('5'), M(2079, 4), L('3'), L('7'), L('9'), L('6'), L('4'),
L('1'), L('4'), L('5'), L('1'), L('5'), L('2'), M(1534, 4), L('2'),
L('3'), L('4'), L('3'), L('6'), L('4'), L('5'), L('4'), M(1503, 4),
L('4'), L('4'), L('4'), L('7'), L('9'), L('5'), M(61, 4), M(1316, 4),
M(2279, 5), L('4'), L('1'), M(1323, 4), L('3'), M(773, 4), L('5'), L('2'),
L('3'), L('1'), M(2114, 5), L('1'), L('6'), L('6'), L('1'), M(2227, 4),
L('5'), L('9'), L('6'), L('9'), L('5'), L('3'), L('6'), L('2'),
L('3'), L('1'), L('4'), M(1536, 4), L('2'), L('4'), L('8'), L('4'),
L('9'), L('3'), L('7'), L('1'), L('8'), L('7'), L('1'), L('1'),
L('0'), L('1'), L('4'), L('5'), L('7'), L('6'), L('5'), L('4'),
M(1890, 4), L('0'), L('2'), L('7'), L('9'), L('9'), L('3'), L('4'),
L('4'), L('0'), L('3'), L('7'), L('4'), L('2'), L('0'), L('0'),
L('7'), M(2368, 4), L('7'), L('8'), L('5'), L('3'), L('9'), L('0'),
L('6'), L('2'), L('1'), L('9'), M(666, 5), M(838, 4), L('8'), L('4'),
L('7'), M(979, 5), L('8'), L('3'), L('3'), L('2'), L('1'), L('4'),
L('4'), L('5'), L('7'), L('1'), M(645, 4), M(1911, 4), L('4'), L('3'),
L('5'), L('0'), M(2345, 4), M(1129, 4), L('5'), L('3'), L('1'), L('9'),
L('1'), L('0'), L('4'), L('8'), L('4'), L('8'), L('1'), L('0'),
L('0'), L('5'), L('3'), L('7'), L('0'), L('6'), M(2237, 4), M(1438, 5),
M(1922, 5), L('1'), M(1370, 4), L('7'), M(796, 4), L('5'), M(2029, 4), M(1037, 4),
L('6'), L('3'), M(2013, 5), L('4'), M(2418, 4), M(847, 5), M(1014, 5), L('8'),
M(1326, 5), M(2184, 5), L('9'), M(392, 4), L('9'), L('1'), M(2255, 4), L('8'),
L('1'), L('4'), L('6'), L('7'), L('5'), L('1'), M(1580, 4), L('1'),
L('2'), L('3'), L('9'), M(426, 6), L('9'), L('0'), L('7'), L('1'),
L('8'), L('6'), L('4'), L('9'), L('4'), L('2'), L('3'), L('1'),
L('9'), L('6'), L('1'), L('5'), L('6'), M(493, 4), M(1725, 4), L('9'),
L('5'), M(2343, 4), M(1130, 4), M(284, 4), L('6'), L('0'), L('3'), L('8'),
M(2598, 4), M(368, 4), M(901, 4), L('6'), L('2'), M(1115, 4), L('5'), M(2125, 4),
L('6'), L('3'), L('8'), L('9'), L('3'), L('7'), L('7'), L('8'),
L('7'), M(2246, 4), M(249, 4), L('9'), L('7'), L('9'), L('2'), L('0'),
L('7'), L('7'), L('3'), M(1496, 4), L('2'), L('1'), L('8'), L('2'),
L('5'), L('6'), M(2016, 4), L('6'), L('6'), M(1751, 4), L('4'), L('2'),
M(1663, 5), L('6'), M(1767, 4), L('4'), L('4'), M(37, 4), L('5'), L('4'),
L('9'), L('2'), L('0'), L('2'), L('6'), L('0'), L('5'), M(2740, 4),
M(997, 5), L('2'), L('0'), L('1'), L('4'), L('9'), M(1235, 4), L('8'),
L('5'), L('0'), L('7'), L('3'), M(1434, 4), L('6'), L('6'), L('6'),
L('0'), M(405, 4), L('2'), L('4'), L('3'), L('4'), L('0'), M(136, 4),
L('0'), M(1900, 4), L('8'), L('6'), L('3'), M(2391, 4), M(2021, 4), M(1068, 4),
M(373, 4), L('5'), L('7'), L('9'), L('6'), L('2'), L('6'), L('8'),
L('5'), L('6'), M(321, 4), L('5'), L('0'), L('8'), M(1316, 4), L('5'),
L('8'), L('7'), L('9'), L('6'), L('9'), L('9'), M(1810, 4), L('5'),
L('7'), L('4'), M(2585, 4), L('8'), L('4'), L('0'), M(2228, 4), L('1'),
L('4'), L('5'), L('9'), L('1'), M(1933, 4), L('7'), L('0'), M(565, 4),
L('0'), L('1'), M(3048, 4), L('1'), L('2'), M(3189, 4), L('0'), M(964, 4),
L('3'), L('9'), M(2859, 4), M(275, 4), L('7'), L('1'), L('5'), M(945, 4),
L('4'), L('2'), L('0'), M(3059, 5), L('9'), M(3011, 4), L('0'), L('7'),
M(834, 4), M(1942, 4), M(2736, 4), M(3171, 4), L('2'), L('1'), M(2401, 4), L('2'),
L('5'), L('1'), M(1404, 4), M(2373, 4), L('9'), L('2'), M(435, 4), L('8'),
L('2'), L('6'), M(2919, 4), L('2'), M(633, 4), L('3'), L('2'), L('1'),
L('5'), L('7'), L('9'), L('1'), L('9'), L('8'), L('4'), L('1'),
L('4'), M(2172, 5), L('9'), L('1'), L('6'), L('4'), M(1769, 5), L('9'),
M(2905, 5), M(2268, 4), L('7'), L('2'), L('2'), M(802, 4), L('5'), M(2213, 4),
M(322, 4), L('9'), L('1'), L('0'), M(189, 4), M(3164, 4), L('5'), L('2'),
L('8'), L('0'), L('1'), L('7'), M(562, 4), L('7'), L('1'), L('2'),
M(2325, 4), L('8'), L('3'), L('2'), M(884, 4), L('1'), M(1418, 4), L('0'),
L('9'), L('3'), L('5'), L('3'), L('9'), L('6'), L('5'), L('7'),
M(1612, 4), L('1'), L('0'), L('8'), L('3'), M(106, 4), L('5'), L('1'),
M(1915, 4), M(3419, 4), L('1'), L('4'), L('4'), L('4'), L('2'), L('1'),
L('0'), L('0'), M(515, 4), L('0'), L('3'), M(413, 4), L('1'), L('1'),
L('0'), L('3'), M(3202, 4), M(10, 4), M(39, 4), M(1539, 6), L('5'), L('1'),
L('6'), M(1498, 4), M(2180, 5), M(2347, 4), L('5'), M(3139, 5), L('8'), L('5'),
L('1'), L('7'), L('1'), L('4'), L('3'), L('7'), M(1542, 4), M(110, 4),
L('1'), L('5'), L('5'), L('6'), L('5'), L('0'), L('8'), L('8'),
M(954, 4), L('9'), L('8'), L('9'), L('8'), L('5'), L('9'), L('9'),
L('8'), L('2'), L('3'), L('8'), M(464, 4), M(2491, 4), L('3'), M(365, 4),
M(1087, 4), M(2500, 4), L('8'), M(3590, 5), L('3'), L('2'), M(264, 4), L('5'),
M(774, 4), L('3'), M(459, 4), L('9'), M(1052, 4), L('9'), L('8'), M(2174, 4),
L('4'), M(3257, 4), L('7'), M(1612, 4), L('0'), L('7'), M(230, 4), L('4'),
L('8'), L('1'), L('4'), L('1'), M(1338, 4), L('8'), L('5'), L('9'),
L('4'), L('6'), L('1'), M(3018, 4), L('8'), L('0'),
},
},
TestCase{
.input = "huffman-rand-1k.input",
.want = "huffman-rand-1k.{s}.expect",
.want_no_input = "huffman-rand-1k.{s}.expect-noinput",
.tokens = &[_]Token{
L(0xf8), L(0x8b), L(0x96), L(0x76), L(0x48), L(0xd), L(0x85), L(0x94), L(0x25), L(0x80), L(0xaf), L(0xc2), L(0xfe), L(0x8d),
L(0xe8), L(0x20), L(0xeb), L(0x17), L(0x86), L(0xc9), L(0xb7), L(0xc5), L(0xde), L(0x6), L(0xea), L(0x7d), L(0x18), L(0x8b),
L(0xe7), L(0x3e), L(0x7), L(0xda), L(0xdf), L(0xff), L(0x6c), L(0x73), L(0xde), L(0xcc), L(0xe7), L(0x6d), L(0x8d), L(0x4),
L(0x19), L(0x49), L(0x7f), L(0x47), L(0x1f), L(0x48), L(0x15), L(0xb0), L(0xe8), L(0x9e), L(0xf2), L(0x31), L(0x59), L(0xde),
L(0x34), L(0xb4), L(0x5b), L(0xe5), L(0xe0), L(0x9), L(0x11), L(0x30), L(0xc2), L(0x88), L(0x5b), L(0x7c), L(0x5d), L(0x14),
L(0x13), L(0x6f), L(0x23), L(0xa9), L(0xd), L(0xbc), L(0x2d), L(0x23), L(0xbe), L(0xd9), L(0xed), L(0x75), L(0x4), L(0x6c),
L(0x99), L(0xdf), L(0xfd), L(0x70), L(0x66), L(0xe6), L(0xee), L(0xd9), L(0xb1), L(0x9e), L(0x6e), L(0x83), L(0x59), L(0xd5),
L(0xd4), L(0x80), L(0x59), L(0x98), L(0x77), L(0x89), L(0x43), L(0x38), L(0xc9), L(0xaf), L(0x30), L(0x32), L(0x9a), L(0x20),
L(0x1b), L(0x46), L(0x3d), L(0x67), L(0x6e), L(0xd7), L(0x72), L(0x9e), L(0x4e), L(0x21), L(0x4f), L(0xc6), L(0xe0), L(0xd4),
L(0x7b), L(0x4), L(0x8d), L(0xa5), L(0x3), L(0xf6), L(0x5), L(0x9b), L(0x6b), L(0xdc), L(0x2a), L(0x93), L(0x77), L(0x28),
L(0xfd), L(0xb4), L(0x62), L(0xda), L(0x20), L(0xe7), L(0x1f), L(0xab), L(0x6b), L(0x51), L(0x43), L(0x39), L(0x2f), L(0xa0),
L(0x92), L(0x1), L(0x6c), L(0x75), L(0x3e), L(0xf4), L(0x35), L(0xfd), L(0x43), L(0x2e), L(0xf7), L(0xa4), L(0x75), L(0xda),
L(0xea), L(0x9b), L(0xa), L(0x64), L(0xb), L(0xe0), L(0x23), L(0x29), L(0xbd), L(0xf7), L(0xe7), L(0x83), L(0x3c), L(0xfb),
L(0xdf), L(0xb3), L(0xae), L(0x4f), L(0xa4), L(0x47), L(0x55), L(0x99), L(0xde), L(0x2f), L(0x96), L(0x6e), L(0x1c), L(0x43),
L(0x4c), L(0x87), L(0xe2), L(0x7c), L(0xd9), L(0x5f), L(0x4c), L(0x7c), L(0xe8), L(0x90), L(0x3), L(0xdb), L(0x30), L(0x95),
L(0xd6), L(0x22), L(0xc), L(0x47), L(0xb8), L(0x4d), L(0x6b), L(0xbd), L(0x24), L(0x11), L(0xab), L(0x2c), L(0xd7), L(0xbe),
L(0x6e), L(0x7a), L(0xd6), L(0x8), L(0xa3), L(0x98), L(0xd8), L(0xdd), L(0x15), L(0x6a), L(0xfa), L(0x93), L(0x30), L(0x1),
L(0x25), L(0x1d), L(0xa2), L(0x74), L(0x86), L(0x4b), L(0x6a), L(0x95), L(0xe8), L(0xe1), L(0x4e), L(0xe), L(0x76), L(0xb9),
L(0x49), L(0xa9), L(0x5f), L(0xa0), L(0xa6), L(0x63), L(0x3c), L(0x7e), L(0x7e), L(0x20), L(0x13), L(0x4f), L(0xbb), L(0x66),
L(0x92), L(0xb8), L(0x2e), L(0xa4), L(0xfa), L(0x48), L(0xcb), L(0xae), L(0xb9), L(0x3c), L(0xaf), L(0xd3), L(0x1f), L(0xe1),
L(0xd5), L(0x8d), L(0x42), L(0x6d), L(0xf0), L(0xfc), L(0x8c), L(0xc), L(0x0), L(0xde), L(0x40), L(0xab), L(0x8b), L(0x47),
L(0x97), L(0x4e), L(0xa8), L(0xcf), L(0x8e), L(0xdb), L(0xa6), L(0x8b), L(0x20), L(0x9), L(0x84), L(0x7a), L(0x66), L(0xe5),
L(0x98), L(0x29), L(0x2), L(0x95), L(0xe6), L(0x38), L(0x32), L(0x60), L(0x3), L(0xe3), L(0x9a), L(0x1e), L(0x54), L(0xe8),
L(0x63), L(0x80), L(0x48), L(0x9c), L(0xe7), L(0x63), L(0x33), L(0x6e), L(0xa0), L(0x65), L(0x83), L(0xfa), L(0xc6), L(0xba),
L(0x7a), L(0x43), L(0x71), L(0x5), L(0xf5), L(0x68), L(0x69), L(0x85), L(0x9c), L(0xba), L(0x45), L(0xcd), L(0x6b), L(0xb),
L(0x19), L(0xd1), L(0xbb), L(0x7f), L(0x70), L(0x85), L(0x92), L(0xd1), L(0xb4), L(0x64), L(0x82), L(0xb1), L(0xe4), L(0x62),
L(0xc5), L(0x3c), L(0x46), L(0x1f), L(0x92), L(0x31), L(0x1c), L(0x4e), L(0x41), L(0x77), L(0xf7), L(0xe7), L(0x87), L(0xa2),
L(0xf), L(0x6e), L(0xe8), L(0x92), L(0x3), L(0x6b), L(0xa), L(0xe7), L(0xa9), L(0x3b), L(0x11), L(0xda), L(0x66), L(0x8a),
L(0x29), L(0xda), L(0x79), L(0xe1), L(0x64), L(0x8d), L(0xe3), L(0x54), L(0xd4), L(0xf5), L(0xef), L(0x64), L(0x87), L(0x3b),
L(0xf4), L(0xc2), L(0xf4), L(0x71), L(0x13), L(0xa9), L(0xe9), L(0xe0), L(0xa2), L(0x6), L(0x14), L(0xab), L(0x5d), L(0xa7),
L(0x96), L(0x0), L(0xd6), L(0xc3), L(0xcc), L(0x57), L(0xed), L(0x39), L(0x6a), L(0x25), L(0xcd), L(0x76), L(0xea), L(0xba),
L(0x3a), L(0xf2), L(0xa1), L(0x95), L(0x5d), L(0xe5), L(0x71), L(0xcf), L(0x9c), L(0x62), L(0x9e), L(0x6a), L(0xfa), L(0xd5),
L(0x31), L(0xd1), L(0xa8), L(0x66), L(0x30), L(0x33), L(0xaa), L(0x51), L(0x17), L(0x13), L(0x82), L(0x99), L(0xc8), L(0x14),
L(0x60), L(0x9f), L(0x4d), L(0x32), L(0x6d), L(0xda), L(0x19), L(0x26), L(0x21), L(0xdc), L(0x7e), L(0x2e), L(0x25), L(0x67),
L(0x72), L(0xca), L(0xf), L(0x92), L(0xcd), L(0xf6), L(0xd6), L(0xcb), L(0x97), L(0x8a), L(0x33), L(0x58), L(0x73), L(0x70),
L(0x91), L(0x1d), L(0xbf), L(0x28), L(0x23), L(0xa3), L(0xc), L(0xf1), L(0x83), L(0xc3), L(0xc8), L(0x56), L(0x77), L(0x68),
L(0xe3), L(0x82), L(0xba), L(0xb9), L(0x57), L(0x56), L(0x57), L(0x9c), L(0xc3), L(0xd6), L(0x14), L(0x5), L(0x3c), L(0xb1),
L(0xaf), L(0x93), L(0xc8), L(0x8a), L(0x57), L(0x7f), L(0x53), L(0xfa), L(0x2f), L(0xaa), L(0x6e), L(0x66), L(0x83), L(0xfa),
L(0x33), L(0xd1), L(0x21), L(0xab), L(0x1b), L(0x71), L(0xb4), L(0x7c), L(0xda), L(0xfd), L(0xfb), L(0x7f), L(0x20), L(0xab),
L(0x5e), L(0xd5), L(0xca), L(0xfd), L(0xdd), L(0xe0), L(0xee), L(0xda), L(0xba), L(0xa8), L(0x27), L(0x99), L(0x97), L(0x69),
L(0xc1), L(0x3c), L(0x82), L(0x8c), L(0xa), L(0x5c), L(0x2d), L(0x5b), L(0x88), L(0x3e), L(0x34), L(0x35), L(0x86), L(0x37),
L(0x46), L(0x79), L(0xe1), L(0xaa), L(0x19), L(0xfb), L(0xaa), L(0xde), L(0x15), L(0x9), L(0xd), L(0x1a), L(0x57), L(0xff),
L(0xb5), L(0xf), L(0xf3), L(0x2b), L(0x5a), L(0x6a), L(0x4d), L(0x19), L(0x77), L(0x71), L(0x45), L(0xdf), L(0x4f), L(0xb3),
L(0xec), L(0xf1), L(0xeb), L(0x18), L(0x53), L(0x3e), L(0x3b), L(0x47), L(0x8), L(0x9a), L(0x73), L(0xa0), L(0x5c), L(0x8c),
L(0x5f), L(0xeb), L(0xf), L(0x3a), L(0xc2), L(0x43), L(0x67), L(0xb4), L(0x66), L(0x67), L(0x80), L(0x58), L(0xe), L(0xc1),
L(0xec), L(0x40), L(0xd4), L(0x22), L(0x94), L(0xca), L(0xf9), L(0xe8), L(0x92), L(0xe4), L(0x69), L(0x38), L(0xbe), L(0x67),
L(0x64), L(0xca), L(0x50), L(0xc7), L(0x6), L(0x67), L(0x42), L(0x6e), L(0xa3), L(0xf0), L(0xb7), L(0x6c), L(0xf2), L(0xe8),
L(0x5f), L(0xb1), L(0xaf), L(0xe7), L(0xdb), L(0xbb), L(0x77), L(0xb5), L(0xf8), L(0xcb), L(0x8), L(0xc4), L(0x75), L(0x7e),
L(0xc0), L(0xf9), L(0x1c), L(0x7f), L(0x3c), L(0x89), L(0x2f), L(0xd2), L(0x58), L(0x3a), L(0xe2), L(0xf8), L(0x91), L(0xb6),
L(0x7b), L(0x24), L(0x27), L(0xe9), L(0xae), L(0x84), L(0x8b), L(0xde), L(0x74), L(0xac), L(0xfd), L(0xd9), L(0xb7), L(0x69),
L(0x2a), L(0xec), L(0x32), L(0x6f), L(0xf0), L(0x92), L(0x84), L(0xf1), L(0x40), L(0xc), L(0x8a), L(0xbc), L(0x39), L(0x6e),
L(0x2e), L(0x73), L(0xd4), L(0x6e), L(0x8a), L(0x74), L(0x2a), L(0xdc), L(0x60), L(0x1f), L(0xa3), L(0x7), L(0xde), L(0x75),
L(0x8b), L(0x74), L(0xc8), L(0xfe), L(0x63), L(0x75), L(0xf6), L(0x3d), L(0x63), L(0xac), L(0x33), L(0x89), L(0xc3), L(0xf0),
L(0xf8), L(0x2d), L(0x6b), L(0xb4), L(0x9e), L(0x74), L(0x8b), L(0x5c), L(0x33), L(0xb4), L(0xca), L(0xa8), L(0xe4), L(0x99),
L(0xb6), L(0x90), L(0xa1), L(0xef), L(0xf), L(0xd3), L(0x61), L(0xb2), L(0xc6), L(0x1a), L(0x94), L(0x7c), L(0x44), L(0x55),
L(0xf4), L(0x45), L(0xff), L(0x9e), L(0xa5), L(0x5a), L(0xc6), L(0xa0), L(0xe8), L(0x2a), L(0xc1), L(0x8d), L(0x6f), L(0x34),
L(0x11), L(0xb9), L(0xbe), L(0x4e), L(0xd9), L(0x87), L(0x97), L(0x73), L(0xcf), L(0x3d), L(0x23), L(0xae), L(0xd5), L(0x1a),
L(0x5e), L(0xae), L(0x5d), L(0x6a), L(0x3), L(0xf9), L(0x22), L(0xd), L(0x10), L(0xd9), L(0x47), L(0x69), L(0x15), L(0x3f),
L(0xee), L(0x52), L(0xa3), L(0x8), L(0xd2), L(0x3c), L(0x51), L(0xf4), L(0xf8), L(0x9d), L(0xe4), L(0x98), L(0x89), L(0xc8),
L(0x67), L(0x39), L(0xd5), L(0x5e), L(0x35), L(0x78), L(0x27), L(0xe8), L(0x3c), L(0x80), L(0xae), L(0x79), L(0x71), L(0xd2),
L(0x93), L(0xf4), L(0xaa), L(0x51), L(0x12), L(0x1c), L(0x4b), L(0x1b), L(0xe5), L(0x6e), L(0x15), L(0x6f), L(0xe4), L(0xbb),
L(0x51), L(0x9b), L(0x45), L(0x9f), L(0xf9), L(0xc4), L(0x8c), L(0x2a), L(0xfb), L(0x1a), L(0xdf), L(0x55), L(0xd3), L(0x48),
L(0x93), L(0x27), L(0x1), L(0x26), L(0xc2), L(0x6b), L(0x55), L(0x6d), L(0xa2), L(0xfb), L(0x84), L(0x8b), L(0xc9), L(0x9e),
L(0x28), L(0xc2), L(0xef), L(0x1a), L(0x24), L(0xec), L(0x9b), L(0xae), L(0xbd), L(0x60), L(0xe9), L(0x15), L(0x35), L(0xee),
L(0x42), L(0xa4), L(0x33), L(0x5b), L(0xfa), L(0xf), L(0xb6), L(0xf7), L(0x1), L(0xa6), L(0x2), L(0x4c), L(0xca), L(0x90),
L(0x58), L(0x3a), L(0x96), L(0x41), L(0xe7), L(0xcb), L(0x9), L(0x8c), L(0xdb), L(0x85), L(0x4d), L(0xa8), L(0x89), L(0xf3),
L(0xb5), L(0x8e), L(0xfd), L(0x75), L(0x5b), L(0x4f), L(0xed), L(0xde), L(0x3f), L(0xeb), L(0x38), L(0xa3), L(0xbe), L(0xb0),
L(0x73), L(0xfc), L(0xb8), L(0x54), L(0xf7), L(0x4c), L(0x30), L(0x67), L(0x2e), L(0x38), L(0xa2), L(0x54), L(0x18), L(0xba),
L(0x8), L(0xbf), L(0xf2), L(0x39), L(0xd5), L(0xfe), L(0xa5), L(0x41), L(0xc6), L(0x66), L(0x66), L(0xba), L(0x81), L(0xef),
L(0x67), L(0xe4), L(0xe6), L(0x3c), L(0xc), L(0xca), L(0xa4), L(0xa), L(0x79), L(0xb3), L(0x57), L(0x8b), L(0x8a), L(0x75),
L(0x98), L(0x18), L(0x42), L(0x2f), L(0x29), L(0xa3), L(0x82), L(0xef), L(0x9f), L(0x86), L(0x6), L(0x23), L(0xe1), L(0x75),
L(0xfa), L(0x8), L(0xb1), L(0xde), L(0x17), L(0x4a),
},
},
TestCase{
.input = "huffman-rand-limit.input",
.want = "huffman-rand-limit.{s}.expect",
.want_no_input = "huffman-rand-limit.{s}.expect-noinput",
.tokens = &[_]Token{
L(0x61), M(1, 74), L(0xa), L(0xf8), L(0x8b), L(0x96), L(0x76), L(0x48), L(0xa), L(0x85), L(0x94), L(0x25), L(0x80),
L(0xaf), L(0xc2), L(0xfe), L(0x8d), L(0xe8), L(0x20), L(0xeb), L(0x17), L(0x86), L(0xc9), L(0xb7), L(0xc5), L(0xde),
L(0x6), L(0xea), L(0x7d), L(0x18), L(0x8b), L(0xe7), L(0x3e), L(0x7), L(0xda), L(0xdf), L(0xff), L(0x6c), L(0x73),
L(0xde), L(0xcc), L(0xe7), L(0x6d), L(0x8d), L(0x4), L(0x19), L(0x49), L(0x7f), L(0x47), L(0x1f), L(0x48), L(0x15),
L(0xb0), L(0xe8), L(0x9e), L(0xf2), L(0x31), L(0x59), L(0xde), L(0x34), L(0xb4), L(0x5b), L(0xe5), L(0xe0), L(0x9),
L(0x11), L(0x30), L(0xc2), L(0x88), L(0x5b), L(0x7c), L(0x5d), L(0x14), L(0x13), L(0x6f), L(0x23), L(0xa9), L(0xa),
L(0xbc), L(0x2d), L(0x23), L(0xbe), L(0xd9), L(0xed), L(0x75), L(0x4), L(0x6c), L(0x99), L(0xdf), L(0xfd), L(0x70),
L(0x66), L(0xe6), L(0xee), L(0xd9), L(0xb1), L(0x9e), L(0x6e), L(0x83), L(0x59), L(0xd5), L(0xd4), L(0x80), L(0x59),
L(0x98), L(0x77), L(0x89), L(0x43), L(0x38), L(0xc9), L(0xaf), L(0x30), L(0x32), L(0x9a), L(0x20), L(0x1b), L(0x46),
L(0x3d), L(0x67), L(0x6e), L(0xd7), L(0x72), L(0x9e), L(0x4e), L(0x21), L(0x4f), L(0xc6), L(0xe0), L(0xd4), L(0x7b),
L(0x4), L(0x8d), L(0xa5), L(0x3), L(0xf6), L(0x5), L(0x9b), L(0x6b), L(0xdc), L(0x2a), L(0x93), L(0x77), L(0x28),
L(0xfd), L(0xb4), L(0x62), L(0xda), L(0x20), L(0xe7), L(0x1f), L(0xab), L(0x6b), L(0x51), L(0x43), L(0x39), L(0x2f),
L(0xa0), L(0x92), L(0x1), L(0x6c), L(0x75), L(0x3e), L(0xf4), L(0x35), L(0xfd), L(0x43), L(0x2e), L(0xf7), L(0xa4),
L(0x75), L(0xda), L(0xea), L(0x9b), L(0xa),
},
},
TestCase{
.input = "huffman-shifts.input",
.want = "huffman-shifts.{s}.expect",
.want_no_input = "huffman-shifts.{s}.expect-noinput",
.tokens = &[_]Token{
L('1'), L('0'), M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258),
M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258),
M(2, 258), M(2, 76), L(0xd), L(0xa), L('2'), L('3'), M(2, 258), M(2, 258),
M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 258), M(2, 256),
},
},
TestCase{
.input = "huffman-text-shift.input",
.want = "huffman-text-shift.{s}.expect",
.want_no_input = "huffman-text-shift.{s}.expect-noinput",
.tokens = &[_]Token{
L('/'), L('/'), L('C'), L('o'), L('p'), L('y'), L('r'), L('i'),
L('g'), L('h'), L('t'), L('2'), L('0'), L('0'), L('9'), L('T'),
L('h'), L('G'), L('o'), L('A'), L('u'), L('t'), L('h'), L('o'),
L('r'), L('.'), L('A'), L('l'), L('l'), M(23, 5), L('r'), L('r'),
L('v'), L('d'), L('.'), L(0xd), L(0xa), L('/'), L('/'), L('U'),
L('o'), L('f'), L('t'), L('h'), L('i'), L('o'), L('u'), L('r'),
L('c'), L('c'), L('o'), L('d'), L('i'), L('g'), L('o'), L('v'),
L('r'), L('n'), L('d'), L('b'), L('y'), L('B'), L('S'), L('D'),
L('-'), L('t'), L('y'), L('l'), M(33, 4), L('l'), L('i'), L('c'),
L('n'), L('t'), L('h'), L('t'), L('c'), L('n'), L('b'), L('f'),
L('o'), L('u'), L('n'), L('d'), L('i'), L('n'), L('t'), L('h'),
L('L'), L('I'), L('C'), L('E'), L('N'), L('S'), L('E'), L('f'),
L('i'), L('l'), L('.'), L(0xd), L(0xa), L(0xd), L(0xa), L('p'),
L('c'), L('k'), L('g'), L('m'), L('i'), L('n'), M(11, 4), L('i'),
L('m'), L('p'), L('o'), L('r'), L('t'), L('"'), L('o'), L('"'),
M(13, 4), L('f'), L('u'), L('n'), L('c'), L('m'), L('i'), L('n'),
L('('), L(')'), L('{'), L(0xd), L(0xa), L(0x9), L('v'), L('r'),
L('b'), L('='), L('m'), L('k'), L('('), L('['), L(']'), L('b'),
L('y'), L('t'), L(','), L('6'), L('5'), L('5'), L('3'), L('5'),
L(')'), L(0xd), L(0xa), L(0x9), L('f'), L(','), L('_'), L(':'),
L('='), L('o'), L('.'), L('C'), L('r'), L('t'), L('('), L('"'),
L('h'), L('u'), L('f'), L('f'), L('m'), L('n'), L('-'), L('n'),
L('u'), L('l'), L('l'), L('-'), L('m'), L('x'), L('.'), L('i'),
L('n'), L('"'), M(34, 5), L('.'), L('W'), L('r'), L('i'), L('t'),
L('('), L('b'), L(')'), L(0xd), L(0xa), L('}'), L(0xd), L(0xa),
L('A'), L('B'), L('C'), L('D'), L('E'), L('F'), L('G'), L('H'),
L('I'), L('J'), L('K'), L('L'), L('M'), L('N'), L('O'), L('P'),
L('Q'), L('R'), L('S'), L('T'), L('U'), L('V'), L('X'), L('x'),
L('y'), L('z'), L('!'), L('"'), L('#'), L(0xc2), L(0xa4), L('%'),
L('&'), L('/'), L('?'), L('"'),
},
},
TestCase{
.input = "huffman-text.input",
.want = "huffman-text.{s}.expect",
.want_no_input = "huffman-text.{s}.expect-noinput",
.tokens = &[_]Token{
L('/'), L('/'), L(' '), L('z'), L('i'), L('g'), L(' '), L('v'),
L('0'), L('.'), L('1'), L('0'), L('.'), L('0'), L(0xa), L('/'),
L('/'), L(' '), L('c'), L('r'), L('e'), L('a'), L('t'), L('e'),
L(' '), L('a'), L(' '), L('f'), L('i'), L('l'), L('e'), M(5, 4),
L('l'), L('e'), L('d'), L(' '), L('w'), L('i'), L('t'), L('h'),
L(' '), L('0'), L('x'), L('0'), L('0'), L(0xa), L('c'), L('o'),
L('n'), L('s'), L('t'), L(' '), L('s'), L('t'), L('d'), L(' '),
L('='), L(' '), L('@'), L('i'), L('m'), L('p'), L('o'), L('r'),
L('t'), L('('), L('"'), L('s'), L('t'), L('d'), L('"'), L(')'),
L(';'), L(0xa), L(0xa), L('p'), L('u'), L('b'), L(' '), L('f'),
L('n'), L(' '), L('m'), L('a'), L('i'), L('n'), L('('), L(')'),
L(' '), L('!'), L('v'), L('o'), L('i'), L('d'), L(' '), L('{'),
L(0xa), L(' '), L(' '), L(' '), L(' '), L('v'), L('a'), L('r'),
L(' '), L('b'), L(' '), L('='), L(' '), L('['), L('1'), L(']'),
L('u'), L('8'), L('{'), L('0'), L('}'), L(' '), L('*'), L('*'),
L(' '), L('6'), L('5'), L('5'), L('3'), L('5'), L(';'), M(31, 5),
M(86, 6), L('f'), L(' '), L('='), L(' '), L('t'), L('r'), L('y'),
M(94, 4), L('.'), L('f'), L('s'), L('.'), L('c'), L('w'), L('d'),
L('('), L(')'), L('.'), M(144, 6), L('F'), L('i'), L('l'), L('e'),
L('('), M(43, 5), M(1, 4), L('"'), L('h'), L('u'), L('f'), L('f'),
L('m'), L('a'), L('n'), L('-'), L('n'), L('u'), L('l'), L('l'),
L('-'), L('m'), L('a'), L('x'), L('.'), L('i'), L('n'), L('"'),
L(','), M(31, 9), L('.'), L('{'), L(' '), L('.'), L('r'), L('e'),
L('a'), L('d'), M(79, 5), L('u'), L('e'), L(' '), L('}'), M(27, 6),
L(')'), M(108, 6), L('d'), L('e'), L('f'), L('e'), L('r'), L(' '),
L('f'), L('.'), L('c'), L('l'), L('o'), L('s'), L('e'), L('('),
M(183, 4), M(22, 4), L('_'), M(124, 7), L('f'), L('.'), L('w'), L('r'),
L('i'), L('t'), L('e'), L('A'), L('l'), L('l'), L('('), L('b'),
L('['), L('0'), L('.'), L('.'), L(']'), L(')'), L(';'), L(0xa),
L('}'), L(0xa),
},
},
TestCase{
.input = "huffman-zero.input",
.want = "huffman-zero.{s}.expect",
.want_no_input = "huffman-zero.{s}.expect-noinput",
.tokens = &[_]Token{ L(0x30), ml, M(1, 49) },
},
TestCase{
.input = "",
.want = "",
.want_no_input = "null-long-match.{s}.expect-noinput",
.tokens = &[_]Token{
L(0x0), ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml,
ml, ml, ml, M(1, 8),
},
},
};
};

0
lib/std/compress/deflate/testdata/huffman-null-max.dyn.expect → lib/std/compress/flate/testdata/block_writer/huffman-null-max.dyn.expect vendored
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0
lib/std/compress/deflate/testdata/huffman-null-max.dyn.expect-noinput → lib/std/compress/flate/testdata/block_writer/huffman-null-max.dyn.expect-noinput vendored
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lib/std/compress/deflate/testdata/huffman-text.wb.expect → lib/std/compress/flate/testdata/block_writer/huffman-text.wb.expect vendored
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lib/std/compress/deflate/testdata/huffman-zero.wb.expect → lib/std/compress/flate/testdata/block_writer/huffman-zero.wb.expect vendored
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lib/std/compress/flate/testdata/fuzz/deflate-stream.expect vendored Normal file
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@@ -0,0 +1,22 @@
[
{ id: "brieflz",
name: "BriefLZ",
libraryUrl: "https://github.com/jibsen/brieflz",
license: "MIT",
revision: "bcaa6a1ee7ccf005512b5c23aa92b40cf75f9ed1",
codecs: [ { name: "brieflz" } ], },
{ id: "brotli",
name: "Brotli",
libraryUrl: "https://github.com/google/brotli",
license: "Apache 2.0",
revision: "1dd66ef114fd244778d9dcb5da09c28b49a0df33",
codecs: [ { name: "brotli",
levels: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
streaming: true } ], },
{ id: "bsc",
name: "bsc",
libraryUrl: "http://libbsc.com/",
license: "Apache 2.0",
revision: "b2b07421381b19b2fada8b291f3cdead10578abc",
codecs: [ { name: "bsc" } ] }
]

3
lib/std/compress/flate/testdata/fuzz/deflate-stream.input vendored Normal file
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@@ -0,0 +1,3 @@
•<EFBFBD>=oÂ0†çò+Ṉ<>„ÄÙÚ­R»µKƒ}>W!AI@j+þ{
¨|ˆª–¼<çóÝóÎFÎx[ÀØ´ž\õ9f;Pë%ü0৷#®¼iuûñÚV¡¸èûUWDQéûÅÚL°YFïÞtTGç¿U©î†Ÿ_Ž´¥<C2B4>ï|SãQë©D¢ã<M…4)ÊXk%MÂÑe©SdűKØ0 û]Ca s[vª×ô•¿´;¡É•MSV™ó®ƒÛýJã‚@Nø5EaítJNˆÄY™$Y–[eѤVs…27‰Òܺ8¾­¸}wÓ†ª¡.H1ƒ„AÊ`Ê c<>3P W̺¾%½ôuY@ß®éjNž‡ô]$
,<ÙôïLŒ4<K¤ˆsa„2Òi«s#•p1ZÒVð4˵Á›™„ýØŽæ£o

BIN
lib/std/compress/flate/testdata/fuzz/empty-distance-alphabet01.input vendored Normal file
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lib/std/compress/flate/testdata/fuzz/empty-distance-alphabet02.input vendored Normal file
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1
lib/std/compress/flate/testdata/fuzz/end-of-stream.input vendored Normal file
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@@ -0,0 +1 @@
武=oﾂ0<10>0

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lib/std/compress/flate/testdata/fuzz/invalid-distance.input vendored Normal file
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1
lib/std/compress/flate/testdata/fuzz/invalid-tree01.input vendored Normal file
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000

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lib/std/compress/flate/testdata/fuzz/invalid-tree02.input vendored Normal file
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lib/std/compress/flate/testdata/fuzz/invalid-tree03.input vendored Normal file
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1
lib/std/compress/flate/testdata/fuzz/lengths-overflow.input vendored Normal file
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<EFBFBD>$<24><><EFBFBD>9

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lib/std/compress/flate/testdata/fuzz/out-of-codes.input vendored Normal file
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