1
2 /* intel_init.c - SSE2 optimized filter functions
3 *
4 * Copyright (c) 2016-2017 Glenn Randers-Pehrson
5 * Written by Mike Klein and Matt Sarett, Google, Inc.
6 * Derived from arm/arm_init.c
7 *
8 * Last changed in libpng 1.6.29 [March 16, 2017]
9 *
10 * This code is released under the libpng license.
11 * For conditions of distribution and use, see the disclaimer
12 * and license in png.h
13 */
14
15 #include "../pngpriv.h"
16
17 #ifdef PNG_READ_SUPPORTED
18 #if PNG_INTEL_SSE_IMPLEMENTATION > 0
19
20 void
png_init_filter_functions_sse2(png_structp pp,unsigned int bpp)21 png_init_filter_functions_sse2(png_structp pp, unsigned int bpp)
22 {
23 /* The techniques used to implement each of these filters in SSE operate on
24 * one pixel at a time.
25 * So they generally speed up 3bpp images about 3x, 4bpp images about 4x.
26 * They can scale up to 6 and 8 bpp images and down to 2 bpp images,
27 * but they'd not likely have any benefit for 1bpp images.
28 * Most of these can be implemented using only MMX and 64-bit registers,
29 * but they end up a bit slower than using the equally-ubiquitous SSE2.
30 */
31 png_debug(1, "in png_init_filter_functions_sse2");
32 if (bpp == 3)
33 {
34 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_sse2;
35 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_sse2;
36 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
37 png_read_filter_row_paeth3_sse2;
38 }
39 else if (bpp == 4)
40 {
41 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_sse2;
42 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_sse2;
43 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
44 png_read_filter_row_paeth4_sse2;
45 }
46
47 /* No need optimize PNG_FILTER_VALUE_UP. The compiler should
48 * autovectorize.
49 */
50 }
51
52 #endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
53 #endif /* PNG_READ_SUPPORTED */
54