mirror of https://github.com/tidwall/tile38.git
25 lines
630 B
Go
25 lines
630 B
Go
// +build amd64,go1.6
|
|
|
|
package geohash
|
|
|
|
// useAsm flag determines whether the assembly version of EncodeInt will be
|
|
// used. By Default we fall back to encodeInt.
|
|
var useAsm bool
|
|
|
|
// cpuid executes the CPUID instruction to obtain processor identification and
|
|
// feature information.
|
|
func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
|
|
|
|
// hasBMI2 returns whether the CPU supports Bit Manipulation Instruction Set
|
|
// 2.
|
|
func hasBMI2() bool {
|
|
_, ebx, _, _ := cpuid(7, 0)
|
|
return ebx&(1<<8) != 0
|
|
}
|
|
|
|
// init determines whether to use assembly version by performing CPU feature
|
|
// check.
|
|
func init() {
|
|
useAsm = hasBMI2()
|
|
}
|