[FFmpeg-cvslog] r21219 - in trunk/libavcodec: aac.c arm/aac.h

[Alex Converse]

2010/1/15 M?ns Rullg?rd <mans at mansr.com>:
> Michael Niedermayer <michaelni at gmx.at> writes:
>
>> On Fri, Jan 15, 2010 at 09:17:24PM +0000, M?ns Rullg?rd wrote:
>>> Michael Niedermayer <michaelni at gmx.at> writes:
>>>
>>> > maybe a header that describes in english what the functions do and contains
>>> > ISO C implementations named like VMUL2_C.
>>> > And a seperate header for each arch that contains a full set of these
>>> > implementations using "#define VMUL2 VMUL2_C" where no better is available.
>>> > Also there would then be a ISO C only header that contained a
>>> > #define VMUL2 VMUL2_C
>>> > for every function.
>>> > That way there would be no ifdefs except for including the right header
>>>
>>> That would require creating and maintaining dummy headers for every
>>> arch. ?I consider that for more of a burden than looking at 4 simple
>>> ifdefs from time to time.
>>
>> I dont think it would need dummy headers
>>
>> #if ARCH_X86
>> #include "x86/foo.h"
>> #else if ARCH_ARM
>> #include "arm/foo.h"
>> #else
>> #include "foo.h"
>> #endif
>> // not yet implemented for alpha & sparc
>
> What if only a subset is implemented for some arch?
>
>> also, having a complete list of optimized functions in each arch file is a
>> great reminder of what is not optimized yet and could be optimized.
>
> It also means that any changes have to be done to *all* arch headers.
> I know from experience that this will not work very well.
>

It doesn't ahve to be taht bad. Consider...

+++ aacopt.h
static av_always_inline float FUNC_C(...) {
    //ISO C90 stuff
}
#define FUNC FUNC_C

+++ arm/aac.h
#include "aacopt.h"
static av_always_inline float FUNC_NEON(...) {
   //Your super awesome neon stuff
}
#undef FUNC
#define FUNC FUNC_NEON

Adding new functions doesn't break any other archs.

The unused static functions should be eliminated at compile time.

Everybody wins!

>> anyway iam not aac maintainer so its none of my business but for files
>> i maintain i dont want such ifdefery
>
> Files you maintain? ?Bah! ?As far as I can tell, I'm the only one
> doing anything resembling $arch maintenance, and I've *reduced* the
> amount of ugly ifdeffery substantially compared to what it used to be,
> so please don't complain to me. ?There is still a lot of cleanup work
> to be done, but I hope to get round to it sooner or later.
>

I was unaware cleaning up after others gives you license to make new messes.