Ganesh Ajjanagadde 07a8fbaa55 lavc/nellymoserenc: avoid wasteful pow ...

exp2 suffices here. Some trivial speedup is done in addition here by
reusing results.

This retains accuracy, and in particular results in identical values
with GNU libm + gcc/clang.

sample benchmark (Haswell, GNU/Linux):
proposed : 424160 decicycles in pow_table,     512 runs,      0 skips
exp2 only: 1262093 decicycles in pow_table,     512 runs,      0 skips
old      : 2849085 decicycles in pow_table,     512 runs,      0 skips

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>

2015-12-17 08:12:41 -08:00

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