authorgravatar for marc@tiehu.isMarc Tiehuis <marc@tiehu.is> 2022-03-10 18:27:26+13:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2022-03-10 13:56:07-05:00
log8bab1b405f0b398a7e98e373f9d0cc26cb8496a6
tree56aa036324d3b0d2990f2e7c2067117ef0675840
parent6e49ba77f3001fe04d4b2177a5c37d28bd422758

math: fix big.int div, gcd and bitAnd edge-cases

Fixes #10932.

2 files changed, 68 insertions(+), 2 deletions(-)

lib/std/math/big/int.zig+6-2
......@@ -1358,7 +1358,7 @@ pub const Mutable = struct {
13581358 var tmp_x = try Managed.init(limbs_buffer.allocator);
13591359 defer tmp_x.deinit();
13601360
1361 while (y.len() > 1) {
1361 while (y.len() > 1 and !y.eqZero()) {
13621362 assert(x.isPositive() and y.isPositive());
13631363 assert(x.len() >= y.len());
13641364
......@@ -1576,6 +1576,10 @@ pub const Mutable = struct {
15761576 // for i from n down to t + 1, do
15771577 var i = n;
15781578 while (i >= t + 1) : (i -= 1) {
1579 if (x.eqZero()) {
1580 break;
1581 }
1582
15791583 const k = i - t - 1;
15801584 // 3.1.
15811585 // if x_i == y_t:
......@@ -3676,8 +3680,8 @@ fn llsignedor(r: []Limb, a: []const Limb, a_positive: bool, b: []const Limb, b_p
36763680fn llsignedand(r: []Limb, a: []const Limb, a_positive: bool, b: []const Limb, b_positive: bool) bool {
36773681 @setRuntimeSafety(debug_safety);
36783682 assert(a.len != 0 and b.len != 0);
3679 assert(r.len >= a.len);
36803683 assert(a.len >= b.len);
3684 assert(r.len >= if (!a_positive and !b_positive) a.len + 1 else b.len);
36813685
36823686 if (a_positive and b_positive) {
36833687 // Trivial case, result is positive.
lib/std/math/big/int_test.zig+62
......@@ -1345,6 +1345,68 @@ test "big.int div trunc single-single -/-" {
13451345 try testing.expect((try r.to(i32)) == er);
13461346}
13471347
1348test "big.int divFloor #10932" {
1349 var a = try Managed.init(testing.allocator);
1350 defer a.deinit();
1351
1352 var b = try Managed.init(testing.allocator);
1353 defer b.deinit();
1354
1355 var res = try Managed.init(testing.allocator);
1356 defer res.deinit();
1357
1358 try a.setString(10, "40000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000");
1359 try b.setString(10, "8000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000");
1360
1361 var mod = try Managed.init(testing.allocator);
1362 defer mod.deinit();
1363
1364 try res.divFloor(&mod, a.toConst(), b.toConst());
1365
1366 const ress = try res.toString(testing.allocator, 16, .lower);
1367 defer testing.allocator.free(ress);
1368 try testing.expect(std.mem.eql(u8, ress, "194bd136316c046d070b763396297bf8869a605030216b52597015902a172b2a752f62af1568dcd431602f03725bfa62b0be71ae86616210972c0126e173503011ca48c5747ff066d159c95e46b69cbb14c8fc0bd2bf0919f921be96463200000000000000000000000000000000000000000000000000000000000000000000000000000000"));
1369 try testing.expect((try mod.to(i32)) == 0);
1370}
1371
1372test "big.int gcd #10932" {
1373 var a = try Managed.init(testing.allocator);
1374 defer a.deinit();
1375
1376 var b = try Managed.init(testing.allocator);
1377 defer b.deinit();
1378
1379 var res = try Managed.init(testing.allocator);
1380 defer res.deinit();
1381
1382 try a.setString(10, "3000000000000000000000000000000000000000000000000000000000000000000000001461501637330902918203684832716283019655932542975000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000");
1383 try b.setString(10, "10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200001001500000000000000000100000000040000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000003000000000000000000000000000000000000000000000000000058715661000000000000000000000000000000000000023553252000000000180000000000000000000000000000000000000000000000000250000000000000000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001005000002000000000000000000000000000000000000000021000000001000000000000000000000000100000000000000000000000000010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000600000000000000000000000000000000000000000200000000000000000000004000000000000000000000000000000000000000000000301000000000000000000000000000500000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000");
1384
1385 try res.gcd(a, b);
1386
1387 const ress = try res.toString(testing.allocator, 16, .lower);
1388 defer testing.allocator.free(ress);
1389 try testing.expect(std.mem.eql(u8, ress, "1a974a5c9734476ff5a3604bcc678a756beacfc21b4427d1f2c1f56f5d4e411a162c56136e20000000000000000000000000000000"));
1390}
1391
1392test "big.int bitAnd #10932" {
1393 var a = try Managed.init(testing.allocator);
1394 defer a.deinit();
1395
1396 var b = try Managed.init(testing.allocator);
1397 defer b.deinit();
1398
1399 var res = try Managed.init(testing.allocator);
1400 defer res.deinit();
1401
1402 try a.setString(10, "154954885951624787839743960731760616696");
1403 try b.setString(10, "55000000000915215865915724129619485917228346934191537590366734850266784978214506142389798064826139649163838075568111457203909393174933092857416500785632012953993352521899237655507306575657169267399324107627651067352600878339870446048204062696260567762088867991835386857942106708741836433444432529637331429212430394179472179237695833247299409249810963487516399177133175950185719220422442438098353430605822151595560743492661038899294517012784306863064670126197566982968906306814338148792888550378533207318063660581924736840687332023636827401670268933229183389040490792300121030647791095178823932734160000000000000000000000000000000000000555555550000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000");
1404
1405 try res.bitAnd(a, b);
1406
1407 try testing.expect((try res.to(i32)) == 0);
1408}
1409
13481410test "big.int div floor single-single +/+" {
13491411 const u: i32 = 5;
13501412 const v: i32 = 3;