Replace the 2d histograms with uint32_t 1d versions (to avoid
pointer casting and to use the optimized VP8LAddVectorEq).
Change-Id: I90b0fe98390b49e3fd03e3484289571cf7ae6eca
The histograms count the occurrences of len/dist in entropy images.
Those (at most (1<<14) by (1<<14)) are sub-sampled by at least
MIN_HUFFMAN_BITS == 2, hence at most 24 bits in a histogram value.
At most, we multiply by 19 (because the longest histogram is of
size 40 and we do 40>>1, cf code) for the bit cost. So it all fits
in 32 bits.
Change-Id: Ife24b035f54794851ff31f2fac07901f724c6d7f
_mm_set1_epi16 takes a short argument
from clang-7 integer sanitizer:
implicit conversion from type 'int' of value 65280 (32-bit, signed) to
type 'short' changed the value to -256 (16-bit, signed)
Change-Id: Iad64f6209a8c130a7df67515451ded45b3f91702
Changed the code (again) to process 4 pixels at a time. Loop is more
involved, but overall it's faster.
Removed the SSE4.1 implementation which is now slower than SSE2.
Change-Id: I7734e371033ad8929ace7f7e1373ba930d9bb5f1
New implementations: SubtractGreenFromBlueAndRed and TransformColor
around 1-2% faster lossless encoding.
Change-Id: I1668e36fdc316ba55b3b798b91b4a3e36ce62861
