diff options
Diffstat (limited to 'src/vendor/golang.org/x/sys/cpu/hwcap_linux.go')
-rw-r--r-- | src/vendor/golang.org/x/sys/cpu/hwcap_linux.go | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/src/vendor/golang.org/x/sys/cpu/hwcap_linux.go b/src/vendor/golang.org/x/sys/cpu/hwcap_linux.go new file mode 100644 index 0000000..f3baa37 --- /dev/null +++ b/src/vendor/golang.org/x/sys/cpu/hwcap_linux.go @@ -0,0 +1,56 @@ +// 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 +} |