Line data    Source code

       1             : /*
       2             :  * PNG image format
       3             :  * Copyright (c) 2008 Loren Merrit <lorenm@u.washington.edu>
       4             :  *
       5             :  * This file is part of FFmpeg.
       6             :  *
       7             :  * FFmpeg is free software; you can redistribute it and/or
       8             :  * modify it under the terms of the GNU Lesser General Public
       9             :  * License as published by the Free Software Foundation; either
      10             :  * version 2.1 of the License, or (at your option) any later version.
      11             :  *
      12             :  * FFmpeg is distributed in the hope that it will be useful,
      13             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      14             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      15             :  * Lesser General Public License for more details.
      16             :  *
      17             :  * You should have received a copy of the GNU Lesser General Public
      18             :  * License along with FFmpeg; if not, write to the Free Software
      19             :  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
      20             :  */
      21             : 
      22             : #include "libavutil/attributes.h"
      23             : #include "libavutil/common.h"
      24             : #include "png.h"
      25             : #include "pngdsp.h"
      26             : 
      27             : // 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
      28             : #define pb_7f (~0UL / 255 * 0x7f)
      29             : #define pb_80 (~0UL / 255 * 0x80)
      30             : 
      31        6037 : static void add_bytes_l2_c(uint8_t *dst, uint8_t *src1, uint8_t *src2, int w)
      32             : {
      33             :     long i;
      34      486361 :     for (i = 0; i <= w - (int) sizeof(long); i += sizeof(long)) {
      35      480324 :         long a = *(long *)(src1 + i);
      36      480324 :         long b = *(long *)(src2 + i);
      37      480324 :         *(long *)(dst + i) = ((a & pb_7f) + (b & pb_7f)) ^ ((a ^ b) & pb_80);
      38             :     }
      39       17563 :     for (; i < w; i++)
      40       11526 :         dst[i] = src1[i] + src2[i];
      41        6037 : }
      42             : 
      43         100 : av_cold void ff_pngdsp_init(PNGDSPContext *dsp)
      44             : {
      45         100 :     dsp->add_bytes_l2         = add_bytes_l2_c;
      46         100 :     dsp->add_paeth_prediction = ff_add_png_paeth_prediction;
      47             : 
      48             :     if (ARCH_X86)
      49         100 :         ff_pngdsp_init_x86(dsp);
      50         100 : }