commit 1e6a32f1af8066fd0b718b11f00cb09104280f49
author Ronald S. Bultje <rbultje@google.com> Thu Jun 20 15:59:48 2013 -0700
committer Ronald S. Bultje <rbultje@google.com> Thu Jun 20 15:59:48 2013 -0700
tree bdcc489ed869497e0852ef4d139b1c9329c440af
parent 8fb6c58191251792765c2910af3f9d6da22d6c11

SSE2/SSSE3 optimizations and unit test for sub_pixel_avg_variance().

Encoding of bus @ 1500kbps (first 50 frames) goes from 3min57 to
3min35, i.e. approximately a 10.5% speedup. Note that the SIMD versions
which use a bilinear filter (x_offset & 7 || y_offset & 7) aren't
perfectly interleaved, and can probably be improved further in the
future. I've marked this with a few TODOs/FIXMEs in the code.

Change-Id: I5c9e900c0f0d32e431a50fecae213b510b2549f9