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Add alias-safe aligned AV_[RW]N macros

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Originally committed as revision 21880 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Måns Rullgård 2010-02-18 13:44:38 +00:00
parent 7a6053ef72
commit f4a7434f16
1 changed files with 32 additions and 0 deletions
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32
libavutil/intreadwrite.h
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@ -422,6 +422,38 @@ union unaligned_16 { uint16_t l; } __attribute__((packed)) av_alias;
} while(0)
#endif
/*
* The AV_[RW]NA macros access naturally aligned data
* in a type-safe way.
*/
#define AV_RNA(s, p) (((const av_alias##s*)(p))->u##s)
#define AV_WNA(s, p, v) (((av_alias##s*)(p))->u##s = (v))
#ifndef AV_RN16A
# define AV_RN16A(p) AV_RNA(16, p)
#endif
#ifndef AV_RN32A
# define AV_RN32A(p) AV_RNA(32, p)
#endif
#ifndef AV_RN64A
# define AV_RN64A(p) AV_RNA(64, p)
#endif
#ifndef AV_WN16A
# define AV_WN16A(p, v) AV_WNA(16, p, v)
#endif
#ifndef AV_WN32A
# define AV_WN32A(p, v) AV_WNA(32, p, v)
#endif
#ifndef AV_WN64A
# define AV_WN64A(p, v) AV_WNA(64, p, v)
#endif
/* Parameters for AV_COPY*, AV_SWAP*, AV_ZERO* must be
* naturally aligned. They may be implemented using MMX,
* so emms_c() must be called before using any float code