mirror of
https://github.com/golang/go
synced 2024-11-18 19:24:39 -07:00
21 lines
465 B
Go
21 lines
465 B
Go
|
// Copyright 2015 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.
|
||
|
|
|
||
|
|
// +build amd64
|
||
|
|
|
||
|
|
package intsets
|
||
|
|
|
||
|
|
func popcnt(x word) int
|
||
|
|
func havePOPCNT() bool
|
||
|
|
|
||
|
|
var hasPOPCNT = havePOPCNT()
|
||
|
|
|
||
|
|
// popcount returns the population count (number of set bits) of x.
|
||
|
|
func popcount(x word) int {
|
||
|
|
if hasPOPCNT {
|
||
|
|
return popcnt(x)
|
||
|
|
}
|
||
|
|
return popcountTable(x) // faster than Hacker's Delight
|
||
|
|
}
|