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// Copyright 2018 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,!amd64p32,!386
package cpu
import (
"encoding/binary"
"io/ioutil"
"runtime"
)
const (
_AT_HWCAP = 16
_AT_HWCAP2 = 26
procAuxv = "/proc/self/auxv"
uintSize uint = 32 << (^uint(0) >> 63)
)
// For those platforms don't have a 'cpuid' equivalent we use HWCAP/HWCAP2
// These are initialized in cpu_$GOARCH.go
// and should not be changed after they are initialized.
var HWCap uint
var HWCap2 uint
func init() {
buf, err := ioutil.ReadFile(procAuxv)
if err != nil {
panic("read proc auxv failed: " + err.Error())
}
pb := int(uintSize / 8)
for i := 0; i < len(buf)-pb*2; i += pb * 2 {
var tag, val uint
switch uintSize {
case 32:
tag = uint(binary.LittleEndian.Uint32(buf[i:]))
val = uint(binary.LittleEndian.Uint32(buf[i+pb:]))
case 64:
if runtime.GOARCH == "ppc64" {
tag = uint(binary.BigEndian.Uint64(buf[i:]))
val = uint(binary.BigEndian.Uint64(buf[i+pb:]))
} else {
tag = uint(binary.LittleEndian.Uint64(buf[i:]))
val = uint(binary.LittleEndian.Uint64(buf[i+pb:]))
}
}
switch tag {
case _AT_HWCAP:
HWCap = val
case _AT_HWCAP2:
HWCap2 = val
}
}
doinit()
}
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