| // Copyright 2009 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 runtime |
| |
| import "unsafe" |
| |
| const ( |
| _AT_PLATFORM = 15 // introduced in at least 2.6.11 |
| |
| _HWCAP_VFP = 1 << 6 // introduced in at least 2.6.11 |
| _HWCAP_VFPv3 = 1 << 13 // introduced in 2.6.30 |
| _HWCAP_IDIVA = 1 << 17 |
| ) |
| |
| var randomNumber uint32 |
| var armArch uint8 = 6 // we default to ARMv6 |
| var hwcap uint32 // set by archauxv |
| var hardDiv bool // set if a hardware divider is available |
| |
| func archauxv(tag, val uintptr) { |
| switch tag { |
| case _AT_RANDOM: |
| // sysargs filled in startupRandomData, but that |
| // pointer may not be word aligned, so we must treat |
| // it as a byte array. |
| randomNumber = uint32(startupRandomData[4]) | uint32(startupRandomData[5])<<8 | |
| uint32(startupRandomData[6])<<16 | uint32(startupRandomData[7])<<24 |
| |
| case _AT_PLATFORM: // v5l, v6l, v7l |
| t := *(*uint8)(unsafe.Pointer(val + 1)) |
| if '5' <= t && t <= '7' { |
| armArch = t - '0' |
| } |
| |
| case _AT_HWCAP: // CPU capability bit flags |
| hwcap = uint32(val) |
| hardDiv = (hwcap & _HWCAP_IDIVA) != 0 |
| } |
| } |