[flac-dev] [PATCH] new SSE code to calculate autocorrelation

[lvqcl]

This patch accelerates FLAC__lpc_compute_autocorrelation_intrin_sse_lag_NN
routines for AMD and newer Intel CPUs. But it's slower on older Intel CPUs.
('Newer Intel CPUs' means Core i aka Nehalem and newer)

According to tests at HA: <http://www.hydrogenaud.io/forums/index.php?s=&showtopic=101082&view=findpost&p=870753>

  CPU                 flac -5           flac -8

  Athlon XP           +5 %              +2.4 %
  Athlon 64 X2        +9 %              +4 %
  Core i              +7 %              +1 % ... +2.7 %
  Core 2              ?                 -3.5 %

According to Steam HW survey <http://store.steampowered.com/hwsurvey/>
69% of Steam users have SSE4.2 which means that the new code is faster for them.
There are also AMD users that don't have SSE4.2, so I think that about 75%
of Steam users will benefit from this patch.

(If somebody knows a better source of stat data please tell.)
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