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// Copyright 2022 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
//go:build go1.14
// +build go1.14
package apd
import (
"testing"
"testing/quick"
)
//////////////////////////////////////////////////////////////////////////////////
// The following tests were copied from the standard library's math/big package //
//////////////////////////////////////////////////////////////////////////////////
func checkGcd(aBytes, bBytes []byte) bool {
x := new(BigInt)
y := new(BigInt)
a := new(BigInt).SetBytes(aBytes)
b := new(BigInt).SetBytes(bBytes)
d := new(BigInt).GCD(x, y, a, b)
x.Mul(x, a)
y.Mul(y, b)
x.Add(x, y)
return x.Cmp(d) == 0
}
var gcdTests = []struct {
d, x, y, a, b string
}{
// a <= 0 || b <= 0
{"0", "0", "0", "0", "0"},
{"7", "0", "1", "0", "7"},
{"7", "0", "-1", "0", "-7"},
{"11", "1", "0", "11", "0"},
{"7", "-1", "-2", "-77", "35"},
{"935", "-3", "8", "64515", "24310"},
{"935", "-3", "-8", "64515", "-24310"},
{"935", "3", "-8", "-64515", "-24310"},
{"1", "-9", "47", "120", "23"},
{"7", "1", "-2", "77", "35"},
{"935", "-3", "8", "64515", "24310"},
{"935000000000000000", "-3", "8", "64515000000000000000", "24310000000000000000"},
{"1", "-221", "22059940471369027483332068679400581064239780177629666810348940098015901108344", "98920366548084643601728869055592650835572950932266967461790948584315647051443", "991"},
}
func testGcd(t *testing.T, d, x, y, a, b *BigInt) {
var X *BigInt
if x != nil {
X = new(BigInt)
}
var Y *BigInt
if y != nil {
Y = new(BigInt)
}
D := new(BigInt).GCD(X, Y, a, b)
if D.Cmp(d) != 0 {
t.Errorf("GCD(%s, %s, %s, %s): got d = %s, want %s", x, y, a, b, D, d)
}
if x != nil && X.Cmp(x) != 0 {
t.Errorf("GCD(%s, %s, %s, %s): got x = %s, want %s", x, y, a, b, X, x)
}
if y != nil && Y.Cmp(y) != 0 {
t.Errorf("GCD(%s, %s, %s, %s): got y = %s, want %s", x, y, a, b, Y, y)
}
// check results in presence of aliasing (issue #11284)
a2 := new(BigInt).Set(a)
b2 := new(BigInt).Set(b)
a2.GCD(X, Y, a2, b2) // result is same as 1st argument
if a2.Cmp(d) != 0 {
t.Errorf("aliased z = a GCD(%s, %s, %s, %s): got d = %s, want %s", x, y, a, b, a2, d)
}
if x != nil && X.Cmp(x) != 0 {
t.Errorf("aliased z = a GCD(%s, %s, %s, %s): got x = %s, want %s", x, y, a, b, X, x)
}
if y != nil && Y.Cmp(y) != 0 {
t.Errorf("aliased z = a GCD(%s, %s, %s, %s): got y = %s, want %s", x, y, a, b, Y, y)
}
a2 = new(BigInt).Set(a)
b2 = new(BigInt).Set(b)
b2.GCD(X, Y, a2, b2) // result is same as 2nd argument
if b2.Cmp(d) != 0 {
t.Errorf("aliased z = b GCD(%s, %s, %s, %s): got d = %s, want %s", x, y, a, b, b2, d)
}
if x != nil && X.Cmp(x) != 0 {
t.Errorf("aliased z = b GCD(%s, %s, %s, %s): got x = %s, want %s", x, y, a, b, X, x)
}
if y != nil && Y.Cmp(y) != 0 {
t.Errorf("aliased z = b GCD(%s, %s, %s, %s): got y = %s, want %s", x, y, a, b, Y, y)
}
a2 = new(BigInt).Set(a)
b2 = new(BigInt).Set(b)
D = new(BigInt).GCD(a2, b2, a2, b2) // x = a, y = b
if D.Cmp(d) != 0 {
t.Errorf("aliased x = a, y = b GCD(%s, %s, %s, %s): got d = %s, want %s", x, y, a, b, D, d)
}
if x != nil && a2.Cmp(x) != 0 {
t.Errorf("aliased x = a, y = b GCD(%s, %s, %s, %s): got x = %s, want %s", x, y, a, b, a2, x)
}
if y != nil && b2.Cmp(y) != 0 {
t.Errorf("aliased x = a, y = b GCD(%s, %s, %s, %s): got y = %s, want %s", x, y, a, b, b2, y)
}
a2 = new(BigInt).Set(a)
b2 = new(BigInt).Set(b)
D = new(BigInt).GCD(b2, a2, a2, b2) // x = b, y = a
if D.Cmp(d) != 0 {
t.Errorf("aliased x = b, y = a GCD(%s, %s, %s, %s): got d = %s, want %s", x, y, a, b, D, d)
}
if x != nil && b2.Cmp(x) != 0 {
t.Errorf("aliased x = b, y = a GCD(%s, %s, %s, %s): got x = %s, want %s", x, y, a, b, b2, x)
}
if y != nil && a2.Cmp(y) != 0 {
t.Errorf("aliased x = b, y = a GCD(%s, %s, %s, %s): got y = %s, want %s", x, y, a, b, a2, y)
}
}
// This was not supported in go1.13. See https://go.dev/doc/go1.14:
// > The GCD method now allows the inputs a and b to be zero or negative.
func TestBigIntGcd(t *testing.T) {
for _, test := range gcdTests {
d, _ := new(BigInt).SetString(test.d, 0)
x, _ := new(BigInt).SetString(test.x, 0)
y, _ := new(BigInt).SetString(test.y, 0)
a, _ := new(BigInt).SetString(test.a, 0)
b, _ := new(BigInt).SetString(test.b, 0)
testGcd(t, d, nil, nil, a, b)
testGcd(t, d, x, nil, a, b)
testGcd(t, d, nil, y, a, b)
testGcd(t, d, x, y, a, b)
}
if err := quick.Check(checkGcd, nil); err != nil {
t.Error(err)
}
}
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