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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package intsets
import (
"math/rand"
"testing"
)
func TestNLZ(t *testing.T) {
// Test the platform-specific edge case.
// NB: v must be a var (not const) so that the word() conversion is dynamic.
// Otherwise the compiler will report an error.
v := uint64(0x0000801000000000)
n := nlz(word(v))
want := 32 // (on 32-bit)
if bitsPerWord == 64 {
want = 16
}
if n != want {
t.Errorf("%d-bit nlz(%d) = %d, want %d", bitsPerWord, v, n, want)
}
}
// Backdoor for testing.
func (s *Sparse) Check() error { return s.check() }
func dumbPopcount(x word) int {
var popcnt int
for i := uint(0); i < bitsPerWord; i++ {
if x&(1<<i) != 0 {
popcnt++
}
}
return popcnt
}
func TestPopcount(t *testing.T) {
for i := 0; i < 1e5; i++ {
x := word(rand.Uint32())
if bitsPerWord == 64 {
x = x | (word(rand.Uint32()) << 32)
}
want := dumbPopcount(x)
got := popcount(x)
if got != want {
t.Errorf("popcount(%d) = %d, want %d", x, got, want)
}
}
}
func BenchmarkPopcount(b *testing.B) {
for i := 0; i < b.N; i++ {
popcount(word(i))
}
}
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