modti3.zig (1380B) - Raw
1 //! Ported from: 2 //! 3 //! https://github.com/llvm/llvm-project/blob/2ffb1b0413efa9a24eb3c49e710e36f92e2cb50b/compiler-rt/lib/builtins/modti3.c 4 5 const std = @import("std"); 6 const builtin = @import("builtin"); 7 const udivmod = @import("udivmod.zig").udivmod; 8 const common = @import("common.zig"); 9 10 pub const panic = common.panic; 11 12 comptime { 13 if (common.want_windows_v2u64_abi) { 14 @export(&__modti3_windows_x86_64, .{ .name = "__modti3", .linkage = common.linkage, .visibility = common.visibility }); 15 } else { 16 @export(&__modti3, .{ .name = "__modti3", .linkage = common.linkage, .visibility = common.visibility }); 17 } 18 } 19 20 pub fn __modti3(a: i128, b: i128) callconv(.c) i128 { 21 return mod(a, b); 22 } 23 24 const v2u64 = @Vector(2, u64); 25 26 fn __modti3_windows_x86_64(a: v2u64, b: v2u64) callconv(.c) v2u64 { 27 return @bitCast(mod(@as(i128, @bitCast(a)), @as(i128, @bitCast(b)))); 28 } 29 30 inline fn mod(a: i128, b: i128) i128 { 31 const s_a = a >> (128 - 1); // s = a < 0 ? -1 : 0 32 const s_b = b >> (128 - 1); // s = b < 0 ? -1 : 0 33 34 const an = (a ^ s_a) -% s_a; // negate if s == -1 35 const bn = (b ^ s_b) -% s_b; // negate if s == -1 36 37 var r: u128 = undefined; 38 _ = udivmod(u128, @as(u128, @bitCast(an)), @as(u128, @bitCast(bn)), &r); 39 return (@as(i128, @bitCast(r)) ^ s_a) -% s_a; // negate if s == -1 40 } 41 42 test { 43 _ = @import("modti3_test.zig"); 44 }