mirror
/
go
mirror of https://github.com/golang/go.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

sync/atomic: explain how to subtract an unsigned constant 

Explain for those unfamiliar with twos-complement arithmetic how to
implement negation of signed positive constant.
Fixes #6408.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/14267044
This commit is contained in:
Rob Pike 2013-10-03 10:40:42 -07:00
parent 01479b6c4a
commit c4579635cf
1 changed files with 4 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/pkg/sync/atomic/doc.go
View File

@ -94,12 +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.