diff options
Diffstat (limited to 'src/pkg/sync/atomic/doc.go')
| -rw-r--r-- | src/pkg/sync/atomic/doc.go | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/src/pkg/sync/atomic/doc.go b/src/pkg/sync/atomic/doc.go index 27a12c984..17ba72fa1 100644 --- a/src/pkg/sync/atomic/doc.go +++ b/src/pkg/sync/atomic/doc.go @@ -13,6 +13,13 @@ // 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: // @@ -40,11 +47,31 @@ import ( // BUG(rsc): On x86-32, 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 both ARM and x86-32, it is the caller's responsibility to arrange for 64-bit // alignment of 64-bit words accessed atomically. The first word in a global // variable or in an allocated struct 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) @@ -67,12 +94,16 @@ func CompareAndSwapPointer(addr *unsafe.Pointer, old, new unsafe.Pointer) (swapp 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. |