github.com/gogf/gkafka@v1.0.1-0.20190702070843-033a14468069/third/golang.org/x/sys/cpu/cpu_linux.go (about)

     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  
     7  package cpu
     8  
     9  import (
    10  	"encoding/binary"
    11  	"io/ioutil"
    12  	"runtime"
    13  )
    14  
    15  const (
    16  	_AT_HWCAP  = 16
    17  	_AT_HWCAP2 = 26
    18  
    19  	procAuxv = "/proc/self/auxv"
    20  
    21  	uintSize uint = 32 << (^uint(0) >> 63)
    22  )
    23  
    24  // For those platforms don't have a 'cpuid' equivalent we use HWCAP/HWCAP2
    25  // These are initialized in cpu_$GOARCH.go
    26  // and should not be changed after they are initialized.
    27  var HWCap uint
    28  var HWCap2 uint
    29  
    30  func init() {
    31  	buf, err := ioutil.ReadFile(procAuxv)
    32  	if err != nil {
    33  		panic("read proc auxv failed: " + err.Error())
    34  	}
    35  
    36  	pb := int(uintSize / 8)
    37  
    38  	for i := 0; i < len(buf)-pb*2; i += pb * 2 {
    39  		var tag, val uint
    40  		switch uintSize {
    41  		case 32:
    42  			tag = uint(binary.LittleEndian.Uint32(buf[i:]))
    43  			val = uint(binary.LittleEndian.Uint32(buf[i+pb:]))
    44  		case 64:
    45  			if runtime.GOARCH == "ppc64" {
    46  				tag = uint(binary.BigEndian.Uint64(buf[i:]))
    47  				val = uint(binary.BigEndian.Uint64(buf[i+pb:]))
    48  			} else {
    49  				tag = uint(binary.LittleEndian.Uint64(buf[i:]))
    50  				val = uint(binary.LittleEndian.Uint64(buf[i+pb:]))
    51  			}
    52  		}
    53  		switch tag {
    54  		case _AT_HWCAP:
    55  			HWCap = val
    56  		case _AT_HWCAP2:
    57  			HWCap2 = val
    58  		}
    59  	}
    60  	doinit()
    61  }