[Ffmpeg-devel] Re: [PATCH] Machine endian bytestream functions

[Ramiro Polla]

Hello,

Reimar D?ffinger escreveu:
> Hello,
> On Sat, Mar 10, 2007 at 11:06:41PM -0300, ramiro at lisha.ufsc.br wrote:
>   
>> Attached patch makes the AV_{R,W}{L,B}xx macros have a machine endian for
>> the simple 16 and 32 bit types. Those macros are then #ifdef'd for the
>> correct endianess. 24 bit remains the same, as it would be more complex.
>>     
>
> They completely ignore alignment issues...
>
>   
You're right.

Attached patch makes use of machine endianess where unaligned data 
accesses are possible, and faster than what gcc is currently doing.

I have only tested this on a p4, but the following program should detect 
this on any architecture. Compile bytes.c and main.c with the same 
options FFmpeg gives to libavcodec files, link them, and test the speed 
both for patched and unpatched FFmpeg. bytes.c should be changed to 'be' 
on big-endian architectures.

Regression tests pass.

Ramiro Polla
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