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// 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.
//go:build arm
package atomic
import (
"internal/cpu"
"unsafe"
)
// Export some functions via linkname to assembly in sync/atomic.
//
//go:linkname Xchg
//go:linkname Xchguintptr
type spinlock struct {
v uint32
}
//go:nosplit
func (l *spinlock) lock() {
for {
if Cas(&l.v, 0, 1) {
return
}
}
}
//go:nosplit
func (l *spinlock) unlock() {
Store(&l.v, 0)
}
var locktab [57]struct {
l spinlock
pad [cpu.CacheLinePadSize - unsafe.Sizeof(spinlock{})]byte
}
func addrLock(addr *uint64) *spinlock {
return &locktab[(uintptr(unsafe.Pointer(addr))>>3)%uintptr(len(locktab))].l
}
// Atomic add and return new value.
//
//go:nosplit
func Xadd(val *uint32, delta int32) uint32 {
for {
oval := *val
nval := oval + uint32(delta)
if Cas(val, oval, nval) {
return nval
}
}
}
//go:noescape
func Xadduintptr(ptr *uintptr, delta uintptr) uintptr
//go:nosplit
func Xchg(addr *uint32, v uint32) uint32 {
for {
old := *addr
if Cas(addr, old, v) {
return old
}
}
}
//go:nosplit
func Xchguintptr(addr *uintptr, v uintptr) uintptr {
return uintptr(Xchg((*uint32)(unsafe.Pointer(addr)), uint32(v)))
}
// Not noescape -- it installs a pointer to addr.
func StorepNoWB(addr unsafe.Pointer, v unsafe.Pointer)
//go:noescape
func Store(addr *uint32, v uint32)
//go:noescape
func StoreRel(addr *uint32, v uint32)
//go:noescape
func StoreReluintptr(addr *uintptr, v uintptr)
//go:nosplit
func goCas64(addr *uint64, old, new uint64) bool {
if uintptr(unsafe.Pointer(addr))&7 != 0 {
*(*int)(nil) = 0 // crash on unaligned uint64
}
_ = *addr // if nil, fault before taking the lock
var ok bool
addrLock(addr).lock()
if *addr == old {
*addr = new
ok = true
}
addrLock(addr).unlock()
return ok
}
//go:nosplit
func goXadd64(addr *uint64, delta int64) uint64 {
if uintptr(unsafe.Pointer(addr))&7 != 0 {
*(*int)(nil) = 0 // crash on unaligned uint64
}
_ = *addr // if nil, fault before taking the lock
var r uint64
addrLock(addr).lock()
r = *addr + uint64(delta)
*addr = r
addrLock(addr).unlock()
return r
}
//go:nosplit
func goXchg64(addr *uint64, v uint64) uint64 {
if uintptr(unsafe.Pointer(addr))&7 != 0 {
*(*int)(nil) = 0 // crash on unaligned uint64
}
_ = *addr // if nil, fault before taking the lock
var r uint64
addrLock(addr).lock()
r = *addr
*addr = v
addrLock(addr).unlock()
return r
}
//go:nosplit
func goLoad64(addr *uint64) uint64 {
if uintptr(unsafe.Pointer(addr))&7 != 0 {
*(*int)(nil) = 0 // crash on unaligned uint64
}
_ = *addr // if nil, fault before taking the lock
var r uint64
addrLock(addr).lock()
r = *addr
addrLock(addr).unlock()
return r
}
//go:nosplit
func goStore64(addr *uint64, v uint64) {
if uintptr(unsafe.Pointer(addr))&7 != 0 {
*(*int)(nil) = 0 // crash on unaligned uint64
}
_ = *addr // if nil, fault before taking the lock
addrLock(addr).lock()
*addr = v
addrLock(addr).unlock()
}
//go:nosplit
func Or8(addr *uint8, v uint8) {
// Align down to 4 bytes and use 32-bit CAS.
uaddr := uintptr(unsafe.Pointer(addr))
addr32 := (*uint32)(unsafe.Pointer(uaddr &^ 3))
word := uint32(v) << ((uaddr & 3) * 8) // little endian
for {
old := *addr32
if Cas(addr32, old, old|word) {
return
}
}
}
//go:nosplit
func And8(addr *uint8, v uint8) {
// Align down to 4 bytes and use 32-bit CAS.
uaddr := uintptr(unsafe.Pointer(addr))
addr32 := (*uint32)(unsafe.Pointer(uaddr &^ 3))
word := uint32(v) << ((uaddr & 3) * 8) // little endian
mask := uint32(0xFF) << ((uaddr & 3) * 8) // little endian
word |= ^mask
for {
old := *addr32
if Cas(addr32, old, old&word) {
return
}
}
}
//go:nosplit
func Or(addr *uint32, v uint32) {
for {
old := *addr
if Cas(addr, old, old|v) {
return
}
}
}
//go:nosplit
func And(addr *uint32, v uint32) {
for {
old := *addr
if Cas(addr, old, old&v) {
return
}
}
}
//go:nosplit
func armcas(ptr *uint32, old, new uint32) bool
//go:noescape
func Load(addr *uint32) uint32
// NO go:noescape annotation; *addr escapes if result escapes (#31525)
func Loadp(addr unsafe.Pointer) unsafe.Pointer
//go:noescape
func Load8(addr *uint8) uint8
//go:noescape
func LoadAcq(addr *uint32) uint32
//go:noescape
func LoadAcquintptr(ptr *uintptr) uintptr
//go:noescape
func Cas64(addr *uint64, old, new uint64) bool
//go:noescape
func CasRel(addr *uint32, old, new uint32) bool
//go:noescape
func Xadd64(addr *uint64, delta int64) uint64
//go:noescape
func Xchg64(addr *uint64, v uint64) uint64
//go:noescape
func Load64(addr *uint64) uint64
//go:noescape
func Store8(addr *uint8, v uint8)
//go:noescape
func Store64(addr *uint64, v uint64)
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