yading@10: /*
yading@10:  * PNG image format
yading@10:  * Copyright (c) 2008 Loren Merrit <lorenm@u.washington.edu>
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #include "libavutil/common.h"
yading@10: #include "png.h"
yading@10: #include "pngdsp.h"
yading@10: 
yading@10: // 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
yading@10: #define pb_7f (~0UL/255 * 0x7f)
yading@10: #define pb_80 (~0UL/255 * 0x80)
yading@10: 
yading@10: static void add_bytes_l2_c(uint8_t *dst, uint8_t *src1, uint8_t *src2, int w)
yading@10: {
yading@10:     long i;
yading@10:     for (i = 0; i <= w - sizeof(long); i += sizeof(long)) {
yading@10:         long a = *(long *)(src1 + i);
yading@10:         long b = *(long *)(src2 + i);
yading@10:         *(long *)(dst + i) = ((a & pb_7f) + (b & pb_7f)) ^ ((a ^ b) & pb_80);
yading@10:     }
yading@10:     for (; i < w; i++)
yading@10:         dst[i] = src1[i] + src2[i];
yading@10: }
yading@10: 
yading@10: void ff_pngdsp_init(PNGDSPContext *dsp)
yading@10: {
yading@10:     dsp->add_bytes_l2         = add_bytes_l2_c;
yading@10:     dsp->add_paeth_prediction = ff_add_png_paeth_prediction;
yading@10: 
yading@10:     if (ARCH_X86) ff_pngdsp_init_x86(dsp);
yading@10: }