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// Copyright 2017 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
const CacheLinePadSize = 32
// arm doesn't have a 'cpuid' equivalent, so we rely on HWCAP/HWCAP2.
// These are initialized by archauxv() and should not be changed after they are
// initialized.
var HWCap uint
var HWCap2 uint
var Platform string
// HWCAP/HWCAP2 bits. These are exposed by Linux and FreeBSD.
const (
hwcap_VFPv4 = 1 << 16
hwcap_IDIVA = 1 << 17
hwcap_LPAE = 1 << 20
)
func doinit() {
options = []option{
{Name: "vfpv4", Feature: &ARM.HasVFPv4},
{Name: "idiva", Feature: &ARM.HasIDIVA},
{Name: "v7atomics", Feature: &ARM.HasV7Atomics},
}
// HWCAP feature bits
ARM.HasVFPv4 = isSet(HWCap, hwcap_VFPv4)
ARM.HasIDIVA = isSet(HWCap, hwcap_IDIVA)
// lpae is required to make the 64-bit instructions LDRD and STRD (and variants) atomic.
// See ARMv7 manual section B1.6.
// We also need at least a v7 chip, for the DMB instruction.
ARM.HasV7Atomics = isSet(HWCap, hwcap_LPAE) && isV7(Platform)
}
func isSet(hwc uint, value uint) bool {
return hwc&value != 0
}
func isV7(s string) bool {
if s == "aarch64" {
return true
}
return s >= "v7" // will be something like v5, v7, v8, v8l
}
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