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big ints: tighten some more division memory requirements

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This commit is contained in:
Robin Voetter
2021-10-24 02:55:23 +02:00
parent 83bdbb2abb
commit c563521d44
2 changed files with 10 additions and 11 deletions
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13
lib/std/math/big/int.zig
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@@ -763,8 +763,8 @@ pub const Mutable = struct {
/// q may alias with a or b.
///
/// Asserts there is enough memory to store q and r.
/// The upper bound for r limb count is b.limbs.len.
/// The upper bound for q limb count is given by `a.limbs.len + b.limbs.len`.
/// The upper bound for r limb count is `b.limbs.len`.
/// The upper bound for q limb count is given by `a.limbs`.
///
/// If `allocator` is provided, it will be used for temporary storage to improve
/// multiplication performance. `error.OutOfMemory` is handled with a fallback algorithm.
@@ -893,9 +893,8 @@ pub const Mutable = struct {
/// q may alias with a or b.
///
/// Asserts there is enough memory to store q and r.
/// The upper bound for r limb count is a.limbs.len.
/// The upper bound for q limb count is given by `calcQuotientLimbLen`. This accounts
/// for temporary space used by the division algorithm.
/// The upper bound for r limb count is `b.limbs.len`.
/// The upper bound for q limb count is given by `a.limbs.len`.
///
/// If `allocator` is provided, it will be used for temporary storage to improve
/// multiplication performance. `error.OutOfMemory` is handled with a fallback algorithm.
@@ -2569,7 +2568,7 @@ pub const Managed = struct {
///
/// Returns an error if memory could not be allocated.
pub fn divFloor(q: *Managed, r: *Managed, a: Const, b: Const) !void {
try q.ensureCapacity(a.limbs.len + b.limbs.len);
try q.ensureCapacity(a.limbs.len);
try r.ensureCapacity(b.limbs.len);
var mq = q.toMutable();
var mr = r.toMutable();
@@ -2586,7 +2585,7 @@ pub const Managed = struct {
///
/// Returns an error if memory could not be allocated.
pub fn divTrunc(q: *Managed, r: *Managed, a: Const, b: Const) !void {
try q.ensureCapacity(a.limbs.len + b.limbs.len);
try q.ensureCapacity(a.limbs.len);
try r.ensureCapacity(b.limbs.len);
var mq = q.toMutable();
var mr = r.toMutable();

8
src/value.zig
View File

@@ -2301,7 +2301,7 @@ pub const Value = extern union {
const rhs_bigint = rhs.toBigInt(&rhs_space);
const limbs_q = try allocator.alloc(
std.math.big.Limb,
lhs_bigint.limbs.len + rhs_bigint.limbs.len,
lhs_bigint.limbs.len,
);
const limbs_r = try allocator.alloc(
std.math.big.Limb,
@@ -2332,7 +2332,7 @@ pub const Value = extern union {
const rhs_bigint = rhs.toBigInt(&rhs_space);
const limbs_q = try allocator.alloc(
std.math.big.Limb,
lhs_bigint.limbs.len + rhs_bigint.limbs.len,
lhs_bigint.limbs.len,
);
const limbs_r = try allocator.alloc(
std.math.big.Limb,
@@ -2363,7 +2363,7 @@ pub const Value = extern union {
const rhs_bigint = rhs.toBigInt(&rhs_space);
const limbs_q = try allocator.alloc(
std.math.big.Limb,
lhs_bigint.limbs.len + rhs_bigint.limbs.len,
lhs_bigint.limbs.len,
);
const limbs_r = try allocator.alloc(
std.math.big.Limb,
@@ -2396,7 +2396,7 @@ pub const Value = extern union {
const rhs_bigint = rhs.toBigInt(&rhs_space);
const limbs_q = try allocator.alloc(
std.math.big.Limb,
lhs_bigint.limbs.len + rhs_bigint.limbs.len,
lhs_bigint.limbs.len,
);
const limbs_r = try allocator.alloc(
std.math.big.Limb,