1// Copyright 2018 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5//+build !amd64,!amd64p32,!386
6
7package cpu
8
9import (
10	"io/ioutil"
11)
12
13const (
14	_AT_HWCAP  = 16
15	_AT_HWCAP2 = 26
16
17	procAuxv = "/proc/self/auxv"
18
19	uintSize = int(32 << (^uint(0) >> 63))
20)
21
22// For those platforms don't have a 'cpuid' equivalent we use HWCAP/HWCAP2
23// These are initialized in cpu_$GOARCH.go
24// and should not be changed after they are initialized.
25var HWCap uint
26var HWCap2 uint
27
28func init() {
29	buf, err := ioutil.ReadFile(procAuxv)
30	if err != nil {
31		panic("read proc auxv failed: " + err.Error())
32	}
33
34	bo := hostByteOrder()
35	for len(buf) >= 2*(uintSize/8) {
36		var tag, val uint
37		switch uintSize {
38		case 32:
39			tag = uint(bo.Uint32(buf[0:]))
40			val = uint(bo.Uint32(buf[4:]))
41			buf = buf[8:]
42		case 64:
43			tag = uint(bo.Uint64(buf[0:]))
44			val = uint(bo.Uint64(buf[8:]))
45			buf = buf[16:]
46		}
47		switch tag {
48		case _AT_HWCAP:
49			HWCap = val
50		case _AT_HWCAP2:
51			HWCap2 = val
52		}
53	}
54	doinit()
55}
56