[FFmpeg-devel] [PATCH] some SIMD write-combining for h264

Måns Rullgård mans
Mon Jan 18 02:36:50 CET 2010

M?ns Rullg?rd <mans at mansr.com> writes:

> Alexander Strange <astrange at ithinksw.com> writes:
>> On Sun, Jan 17, 2010 at 7:54 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
>>> Alexander Strange <astrange <at> ithinksw.com> writes:
>>>> >>> also what sets __MMX__ ? we have our own defines for that
>>>> >>
>>>> >> It's a gcc builtin define, set based on ./configure --cpu=x adding
>>>> >> -march. ?HAVE_MMX is for the build and not the host cpu family, and
>>>> >> this is inlined asm, so it can't use it.
>>>> >
>>>> > Huh? ?Host... build???
>>>> Oh, that was supposed to be "target"...
>>>> Anyway, this is MMX being used like the cmov/clz inlines, so it depends on the
>>>> given --cpu and not on the build system's capabilities.
>>> Could you explain once more why this shouldn't be HAVE_MMX?
>>> If the user passes --disable-mmx to configure, he imo expects MMX to be disabled.
>>> Carl Eugen
>> HAVE_MMX isn't enough to enable it - './configure --cpu=i586' enables
>> HAVE_MMX, but i586 doesn't have it.
> Not anymore.

Hmm, I guess SSE et al have the same problem...

M?ns Rullg?rd
mans at mansr.com

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