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unsafe: document use of &^ to round/align pointers 

Follow-up to CL 27156

Change-Id: I4f1cfced2dced9c9fc8a05bbc00ec4229e85c5c9
Reviewed-on: https://go-review.googlesource.com/27314
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2016-08-17 16:23:40 -07:00
parent a7277e5494
commit 29df4c8f00
1 changed files with 4 additions and 2 deletions
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6
src/unsafe/unsafe.go
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@ -76,8 +76,10 @@ type ArbitraryType int
// // equivalent to e := unsafe.Pointer(&x[i])
// e := unsafe.Pointer(uintptr(unsafe.Pointer(&x[0])) + i*unsafe.Sizeof(x[0]))
//
// It is valid both to add and to subtract offsets from a pointer in this way,
// but the result must continue to point into the original allocated object.
// It is valid both to add and to subtract offsets from a pointer in this way.
// It is also valid to use &^ to round pointers, usually for alignment.
// In all cases, the result must continue to point into the original allocated object.
//
// Unlike in C, it is not valid to advance a pointer just beyond the end of
// its original allocation:
//