[FFmpeg-devel] [PATCH 02/12] mips/float_dsp: replace assembly with C implementations

Nedeljko Babic Nedeljko.Babic at imgtec.com
Wed Mar 4 12:08:20 CET 2015

>The assembly versions have a few problems
>- They only work with mips32r2 enabled
>- They don't work on 64-bits
>- They're massive and complex
>So replace them with C implementations which solve these problems and let GCC
>magically optimize for different platforms. All the functions are manually
>unrolled 4 times (like the assembly code). With the addition of a few restrict
>keywords, the functions produce almost identical assembly to the original
>versions when compiled with gcc -O3.
>Since this code now uses no fpu assembly, drop the HAVE_MIPSFPU guard as well.

All improvements of the C code should be put in generic C code so all architectures
can benefit from them.

The purpose of this code was to create optimizations for specific architecture.
In this way optimizations for mips32r2 architecture are here even without tweaking
configure line and even for older compilers.

By putting these optimizations under HAVE_MIPS32R2 problem with building mips64 should
be resolved and this can be optimized for mips64 later if needed.


More information about the ffmpeg-devel mailing list