[mythtv] [PATCH] Clogged filters

[Nigel Pearson]

>> 1) A lot of the filters have common stuff that should be abstracted
>>     (e.g. mm_support() or emms() for non-Intel compilation,
>>           content of .pro files are nearly identical)
>> 2) Several dummy functions are needlessly defined for non-MMX
>> 3) Altivec accelleration is not determined at run time
>> 4) Using i386 instead of MMX.
> 1/3) Why not have mm_support() return MM_ALTIVEC if altivec is 
> available?
> This is already implemented in libs/libavcodec/ppc/dsputil_ppc.c

	That is the plan - patched linearblend/filter_linearblend.c
(the only filter with Altivec acceleration) uses libavcodec's.


> 2) ok, get rid of these.
> 4) Can't do it. i386 != MMX. MMX is defined when the processor is any
> MMX supporting processor, while i386 is defined when the processor is a
> IA32 processor supporting MMX. The problem is that the instruction
> mnemonics have different meanings on a x86-64, popl still pops a long
> off the stack, but now a long is 64 bits not 32 bits, so it won't fit 
> in
> eax... Anyway, some algorithms have been ported to work on a x86-64, 
> and
> others haven't so we need the two defines.

	Aah. OK, that makes (a bit more) sense now.
Maybe having MMX and MMX64 would be clearer?


>> 	Better names (or other criticism) gladly accepted/debated,
>> otherwise I will commit in a few days?
> Thanks for not committing right away, I already did the
> i386 -> MMX change a few weeks ago, and had to revert...

	I had initially changed all the MMXs to i386,
and the HAVE_ALTIVECs to ARCH_POWERPC, but then had
to think about what MMX or HAVE_ALTIVEC really meant.

	In a perfect world, we might have USE_MMX, USE_MMX64,
and USE_ALTIVEC, which configure would disable if the
build was not that architecture, or the compiler was not
capable of dealing with those extensions. But backwards
compatibility means we are stuck with the current symbols?

--
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