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/* intel_init.c - SSE2 optimized filter functions
*
* Copyright (c) 2016 Google, Inc.
*
* Last changed in libpng 1.6.22 [(PENDING RELEASE)]
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
#include "../../pngpriv.h"
#ifdef PNG_READ_SUPPORTED
#if PNG_INTEL_SSE_IMPLEMENTATION > 0
void
png_init_filter_functions_sse2(png_structp pp, unsigned int bpp)
{
// The techniques used to implement each of these filters in SSE operate on
// one pixel at a time.
// So they generally speed up 3bpp images about 3x, 4bpp images about 4x.
// They can scale up to 6 and 8 bpp images and down to 2 bpp images,
// but they'd not likely have any benefit for 1bpp images.
// Most of these can be implemented using only MMX and 64-bit registers,
// but they end up a bit slower than using the equally-ubiquitous SSE2.
if (bpp == 3)
{
pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_sse2;
pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_sse2;
pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
png_read_filter_row_paeth3_sse2;
}
else if (bpp == 4)
{
pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_sse2;
pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_sse2;
pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
png_read_filter_row_paeth4_sse2;
}
// No need optimize PNG_FILTER_VALUE_UP. The compiler should autovectorize.
}
#endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
#endif /* PNG_READ_SUPPORTED */
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