FFmpeg

20300 Commits

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488 MiB

Tag: Branch: Tree: abfc8d056e

Commit Graph

Author	SHA1	Message	Date
Måns Rullgård	3c55ce039d	ARM asm for AV_RN() ARMv6 and later support unaligned loads and stores for single word/halfword but not double/multiple. GCC is ignorant of this and will always use bytewise accesses for unaligned data. Casting to an int32_t pointer is dangerous since a load/store double or multiple instruction might be used (this happens with some code in FFmpeg). Implementing the AV_[RW] macros with inline asm using only supported instructions gives fast and safe unaligned accesses. ARM RVCT does the right thing with generic code. This gives an overall speedup of up to 10%. Originally committed as revision 18601 to svn://svn.ffmpeg.org/ffmpeg/trunk	16 years ago

Author

SHA1

Message

Date

Måns Rullgård

3c55ce039d

ARM asm for AV_RN*()

ARMv6 and later support unaligned loads and stores for single
word/halfword but not double/multiple.  GCC is ignorant of this and
will always use bytewise accesses for unaligned data.  Casting to an
int32_t pointer is dangerous since a load/store double or multiple
instruction might be used (this happens with some code in FFmpeg).
Implementing the AV_[RW]* macros with inline asm using only supported
instructions gives fast and safe unaligned accesses.  ARM RVCT does
the right thing with generic code.

This gives an overall speedup of up to 10%.

Originally committed as revision 18601 to svn://svn.ffmpeg.org/ffmpeg/trunk

16 years ago

1 Commits (abfc8d056ea99fe69b656dd21f7fdc1e32eaa41f)