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