commit d8a423c62d37f923d0b17f04edd8fc46c2be8824
author David Barker <david.barker@argondesign.com> Wed Apr 19 10:32:43 2017 +0100
committer David Barker <david.barker@argondesign.com> Thu May 04 11:15:26 2017 +0100
tree d8fab80d59a2c7f7e8e8a5a9d30d59b63acd4819
parent 0757fd8f59f9e147f22c8abf86b4891835917587

Add SSSE3 warp filter + const-ify warp filters

The SSSE3 filter is very similar to the SSE2 filter, but
the horizontal pass is sped up by using the 8x8->16
multiplies added in SSSE3.

Also apply const-correctness to all versions of the filter

The timings of the existing filters are unchanged, and the
lowbd SSSE3 filter is ~17% faster than the lowbd SSE2 filter.

Timings per 8x8 block:
lowbd SSE2: 320ns
lowbd SSSE3: 273ns
highbd SSSE3: 300ns

Filter output is unchanged.

Change-Id: Ifb428a33b106d900cde1b080794796c0754ae182