| // Copyright 2011 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 atomic provides low-level atomic memory primitives |
| // useful for implementing synchronization algorithms. |
| // |
| // These functions require great care to be used correctly. |
| // Except for special, low-level applications, synchronization is better |
| // done with channels or the facilities of the sync package. |
| // Share memory by communicating; |
| // don't communicate by sharing memory. |
| // |
| // The swap operation, implemented by the SwapT functions, is the atomic |
| // equivalent of: |
| // |
| // old = *addr |
| // *addr = new |
| // return old |
| // |
| // The compare-and-swap operation, implemented by the CompareAndSwapT |
| // functions, is the atomic equivalent of: |
| // |
| // if *addr == old { |
| // *addr = new |
| // return true |
| // } |
| // return false |
| // |
| // The add operation, implemented by the AddT functions, is the atomic |
| // equivalent of: |
| // |
| // *addr += delta |
| // return *addr |
| // |
| // The load and store operations, implemented by the LoadT and StoreT |
| // functions, are the atomic equivalents of "return *addr" and |
| // "*addr = val". |
| // |
| package atomic |
| |
| import ( |
| "unsafe" |
| ) |
| |
| // BUG(rsc): On 386, the 64-bit functions use instructions unavailable before the Pentium MMX. |
| // |
| // On non-Linux ARM, the 64-bit functions use instructions unavailable before the ARMv6k core. |
| // |
| // On ARM, 386, and 32-bit MIPS, it is the caller's responsibility |
| // to arrange for 64-bit alignment of 64-bit words accessed atomically. |
| // The first word in a variable or in an allocated struct, array, or slice can |
| // be relied upon to be 64-bit aligned. |
| |
| // SwapInt32 atomically stores new into *addr and returns the previous *addr value. |
| func SwapInt32(addr *int32, new int32) (old int32) |
| |
| // SwapInt64 atomically stores new into *addr and returns the previous *addr value. |
| func SwapInt64(addr *int64, new int64) (old int64) |
| |
| // SwapUint32 atomically stores new into *addr and returns the previous *addr value. |
| func SwapUint32(addr *uint32, new uint32) (old uint32) |
| |
| // SwapUint64 atomically stores new into *addr and returns the previous *addr value. |
| func SwapUint64(addr *uint64, new uint64) (old uint64) |
| |
| // SwapUintptr atomically stores new into *addr and returns the previous *addr value. |
| func SwapUintptr(addr *uintptr, new uintptr) (old uintptr) |
| |
| // SwapPointer atomically stores new into *addr and returns the previous *addr value. |
| func SwapPointer(addr *unsafe.Pointer, new unsafe.Pointer) (old unsafe.Pointer) |
| |
| // CompareAndSwapInt32 executes the compare-and-swap operation for an int32 value. |
| func CompareAndSwapInt32(addr *int32, old, new int32) (swapped bool) |
| |
| // CompareAndSwapInt64 executes the compare-and-swap operation for an int64 value. |
| func CompareAndSwapInt64(addr *int64, old, new int64) (swapped bool) |
| |
| // CompareAndSwapUint32 executes the compare-and-swap operation for a uint32 value. |
| func CompareAndSwapUint32(addr *uint32, old, new uint32) (swapped bool) |
| |
| // CompareAndSwapUint64 executes the compare-and-swap operation for a uint64 value. |
| func CompareAndSwapUint64(addr *uint64, old, new uint64) (swapped bool) |
| |
| // CompareAndSwapUintptr executes the compare-and-swap operation for a uintptr value. |
| func CompareAndSwapUintptr(addr *uintptr, old, new uintptr) (swapped bool) |
| |
| // CompareAndSwapPointer executes the compare-and-swap operation for a unsafe.Pointer value. |
| func CompareAndSwapPointer(addr *unsafe.Pointer, old, new unsafe.Pointer) (swapped bool) |
| |
| // AddInt32 atomically adds delta to *addr and returns the new value. |
| func AddInt32(addr *int32, delta int32) (new int32) |
| |
| // AddUint32 atomically adds delta to *addr and returns the new value. |
| // To subtract a signed positive constant value c from x, do AddUint32(&x, ^uint32(c-1)). |
| // In particular, to decrement x, do AddUint32(&x, ^uint32(0)). |
| func AddUint32(addr *uint32, delta uint32) (new uint32) |
| |
| // AddInt64 atomically adds delta to *addr and returns the new value. |
| func AddInt64(addr *int64, delta int64) (new int64) |
| |
| // AddUint64 atomically adds delta to *addr and returns the new value. |
| // To subtract a signed positive constant value c from x, do AddUint64(&x, ^uint64(c-1)). |
| // In particular, to decrement x, do AddUint64(&x, ^uint64(0)). |
| func AddUint64(addr *uint64, delta uint64) (new uint64) |
| |
| // AddUintptr atomically adds delta to *addr and returns the new value. |
| func AddUintptr(addr *uintptr, delta uintptr) (new uintptr) |
| |
| // LoadInt32 atomically loads *addr. |
| func LoadInt32(addr *int32) (val int32) |
| |
| // LoadInt64 atomically loads *addr. |
| func LoadInt64(addr *int64) (val int64) |
| |
| // LoadUint32 atomically loads *addr. |
| func LoadUint32(addr *uint32) (val uint32) |
| |
| // LoadUint64 atomically loads *addr. |
| func LoadUint64(addr *uint64) (val uint64) |
| |
| // LoadUintptr atomically loads *addr. |
| func LoadUintptr(addr *uintptr) (val uintptr) |
| |
| // LoadPointer atomically loads *addr. |
| func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer) |
| |
| // StoreInt32 atomically stores val into *addr. |
| func StoreInt32(addr *int32, val int32) |
| |
| // StoreInt64 atomically stores val into *addr. |
| func StoreInt64(addr *int64, val int64) |
| |
| // StoreUint32 atomically stores val into *addr. |
| func StoreUint32(addr *uint32, val uint32) |
| |
| // StoreUint64 atomically stores val into *addr. |
| func StoreUint64(addr *uint64, val uint64) |
| |
| // StoreUintptr atomically stores val into *addr. |
| func StoreUintptr(addr *uintptr, val uintptr) |
| |
| // StorePointer atomically stores val into *addr. |
| func StorePointer(addr *unsafe.Pointer, val unsafe.Pointer) |