The default timer register pmccntr_el0 usually requires enabling
access with e.g. a kernel module (while it is accessible by
default on Windows). On Linux, the default for checkasm benchmarks
is to use perf (if suitable headers are available) though.
On macOS, using cntvct_el0 gives measurements with the same
magnitude as mach_absolute_time (which is used currently), but
possibly with a little less overhead/noise.
Signed-off-by: Martin Storsjö <martin@martin.st>
It will fallback to mach_absolute_time inside libavutil/timer.h
Reviewed-by: Martin Storsjö <martin@martin.st>
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
This is much less precise than the cycle counter register, but
the cycle counter register is not available on apple platforms
(and on linux, it requires a kernel module for allowing user mode
access).
Signed-off-by: Martin Storsjö <martin@martin.st>
The ISB (instruction synchronization barrier) might be too heavy for
START/STOPTIMER use but should be more accurate in checkasm where the
timing overhead is subtracted.
Consistently apply this rule: the guard name is obtained from the
filename by stripping the leading "lib", converting '/' and '.' to
'_' and uppercasing the resulting name. Guard names in the root
directory have to be prefixed by "FFMPEG_".
Originally committed as revision 15120 to svn://svn.ffmpeg.org/ffmpeg/trunk
depending on CONFIG_SMALL this can either be compiled to a fully unrolled kernel / rfc reference style md5 routine
or a single loop similar to what mplayer uses
Originally committed as revision 5565 to svn://svn.ffmpeg.org/ffmpeg/trunk
Martin Storsjö
Zhao Zhili
Janne Grunau
Mans Rullgard
Stefano Sabatini
Diego Biurrun
Ivo van Poorten
Michael Niedermayer