You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
56 lines
1.2 KiB
56 lines
1.2 KiB
// Copyright 2019 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 cpu
|
|
|
|
import (
|
|
"io/ioutil"
|
|
)
|
|
|
|
const (
|
|
_AT_HWCAP = 16
|
|
_AT_HWCAP2 = 26
|
|
|
|
procAuxv = "/proc/self/auxv"
|
|
|
|
uintSize = int(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 readHWCAP() error {
|
|
buf, err := ioutil.ReadFile(procAuxv)
|
|
if err != nil {
|
|
// e.g. on android /proc/self/auxv is not accessible, so silently
|
|
// ignore the error and leave Initialized = false. On some
|
|
// architectures (e.g. arm64) doinit() implements a fallback
|
|
// readout and will set Initialized = true again.
|
|
return err
|
|
}
|
|
bo := hostByteOrder()
|
|
for len(buf) >= 2*(uintSize/8) {
|
|
var tag, val uint
|
|
switch uintSize {
|
|
case 32:
|
|
tag = uint(bo.Uint32(buf[0:]))
|
|
val = uint(bo.Uint32(buf[4:]))
|
|
buf = buf[8:]
|
|
case 64:
|
|
tag = uint(bo.Uint64(buf[0:]))
|
|
val = uint(bo.Uint64(buf[8:]))
|
|
buf = buf[16:]
|
|
}
|
|
switch tag {
|
|
case _AT_HWCAP:
|
|
hwCap = val
|
|
case _AT_HWCAP2:
|
|
hwCap2 = val
|
|
}
|
|
}
|
|
return nil
|
|
}
|