1
2 /* intel_init.c - SSE2 optimized filter functions
3 *
4 * Copyright (c) 2016 Google, Inc.
5 * Written by Mike Klein and Matt Sarett
6 * Derived from arm/arm_init.c, which was
7 * Copyright (c) 2014,2016 Glenn Randers-Pehrson
8 *
9 * Last changed in libpng 1.6.22 [May 26, 2016]
10 *
11 * This code is released under the libpng license.
12 * For conditions of distribution and use, see the disclaimer
13 * and license in png.h
14 */
15
16 #include "../../pngpriv.h"
17
18 #ifdef PNG_READ_SUPPORTED
19 #if PNG_INTEL_SSE_IMPLEMENTATION > 0
20
21 void
png_init_filter_functions_sse2(png_structp pp,unsigned int bpp)22 png_init_filter_functions_sse2(png_structp pp, unsigned int bpp)
23 {
24 /* The techniques used to implement each of these filters in SSE operate on
25 * one pixel at a time.
26 * So they generally speed up 3bpp images about 3x, 4bpp images about 4x.
27 * They can scale up to 6 and 8 bpp images and down to 2 bpp images,
28 * but they'd not likely have any benefit for 1bpp images.
29 * Most of these can be implemented using only MMX and 64-bit registers,
30 * but they end up a bit slower than using the equally-ubiquitous SSE2.
31 */
32 png_debug(1, "in png_init_filter_functions_sse2");
33 if (bpp == 3)
34 {
35 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_sse2;
36 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_sse2;
37 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
38 png_read_filter_row_paeth3_sse2;
39 }
40 else if (bpp == 4)
41 {
42 pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_sse2;
43 pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_sse2;
44 pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
45 png_read_filter_row_paeth4_sse2;
46 }
47
48 /* No need optimize PNG_FILTER_VALUE_UP. The compiler should
49 * autovectorize.
50 */
51 }
52
53 #endif /* PNG_INTEL_SSE_IMPLEMENTATION > 0 */
54 #endif /* PNG_READ_SUPPORTED */
55