[FFmpeg-devel] [PATCH] MMX VP3 Loop Filter

[Jason Garrett-Glaser]

On Sat, Oct 11, 2008 at 1:53 AM, David Conrad <lessen42 at gmail.com> wrote:
> filter_limit *= 0x02020202;
>"movd     "#flim", %%mm5 \n\t" \
>"punpcklbw  %%mm5, %%mm5 \n\t" \

Which is faster, this, or SPLATB in the form of punpcklbw + pshufw +
psllw (psllw because the filter_limit values are guaranteed to be <
128, so a word left shift is equivalent to a byte left shift)?

The SPLATB would avoid the integer multiply, and perhaps also as
importantly avoid the register->mm move, since you'll be able to load
it directly off the stack.

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