1 
2 /* intel_init.c - SSE2 optimized filter functions
3  *
4  * Copyright (c) 2018 Cosmin Truta
5  * Copyright (c) 2016-2017 Glenn Randers-Pehrson
6  * Written by Mike Klein and Matt Sarett, Google, Inc.
7  * Derived from arm/arm_init.c
8  *
9  * This code is released under the libpng license.
10  * For conditions of distribution and use, see the disclaimer
11  * and license in png.h
12  */
13 
14 #include "../pngpriv.h"
15 
16 #ifdef PNG_READ_SUPPORTED
17 #if PNG_INTEL_SSE_IMPLEMENTATION > 0
18 
19 void
png_init_filter_functions_sse2(png_structp pp,unsigned int bpp)20 png_init_filter_functions_sse2(png_structp pp, unsigned int bpp)
21 {
22    /* The techniques used to implement each of these filters in SSE operate on
23     * one pixel at a time.
24     * So they generally speed up 3bpp images about 3x, 4bpp images about 4x.
25     * They can scale up to 6 and 8 bpp images and down to 2 bpp images,
26     * but they'd not likely have any benefit for 1bpp images.
27     * Most of these can be implemented using only MMX and 64-bit registers,
28     * but they end up a bit slower than using the equally-ubiquitous SSE2.
29    */
30    png_debug(1, "in png_init_filter_functions_sse2");
31    if (bpp == 3)
32    {
33       pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_sse2;
34       pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_sse2;
35       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
36          png_read_filter_row_paeth3_sse2;
37    }
38    else if (bpp == 4)
39    {
40       pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_sse2;
41       pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_sse2;
42       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
43           png_read_filter_row_paeth4_sse2;
44    }
45 
46    /* No need optimize PNG_FILTER_VALUE_UP.  The compiler should
47     * autovectorize.
48     */
49 }
50 
51 #endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
52 #endif /* PNG_READ_SUPPORTED */
53