// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "internal/cpu"
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const (
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_HWCAP_VFP = 1 << 6 // introduced in at least 2.6.11
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_HWCAP_VFPv3 = 1 << 13 // introduced in 2.6.30
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)
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var randomNumber uint32
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func checkgoarm() {
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// On Android, /proc/self/auxv might be unreadable and hwcap won't
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// reflect the CPU capabilities. Assume that every Android arm device
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// has the necessary floating point hardware available.
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if GOOS == "android" {
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return
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}
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if goarm > 5 && cpu.HWCap&_HWCAP_VFP == 0 {
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print("runtime: this CPU has no floating point hardware, so it cannot run\n")
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print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n")
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exit(1)
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}
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if goarm > 6 && cpu.HWCap&_HWCAP_VFPv3 == 0 {
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print("runtime: this CPU has no VFPv3 floating point hardware, so it cannot run\n")
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print("this GOARM=", goarm, " binary. Recompile using GOARM=5 or GOARM=6.\n")
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exit(1)
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}
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}
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func archauxv(tag, val uintptr) {
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switch tag {
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case _AT_RANDOM:
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// sysargs filled in startupRandomData, but that
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// pointer may not be word aligned, so we must treat
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// it as a byte array.
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randomNumber = uint32(startupRandomData[4]) | uint32(startupRandomData[5])<<8 |
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uint32(startupRandomData[6])<<16 | uint32(startupRandomData[7])<<24
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case _AT_HWCAP:
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cpu.HWCap = uint(val)
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case _AT_HWCAP2:
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cpu.HWCap2 = uint(val)
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}
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}
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//go:nosplit
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func cputicks() int64 {
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// Currently cputicks() is used in blocking profiler and to seed fastrand().
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// nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
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// randomNumber provides better seeding of fastrand.
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return nanotime() + int64(randomNumber)
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}
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