/*
  * PNG image format

  * Copyright (c) 2003 Fabrice Bellard

  *

  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

  * version 2.1 of the License, or (at your option) any later version.

  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  */
 #include "avcodec.h"

 #include "png.h"

 
 /* Mask to determine which y pixels are valid in a pass */

 const uint8_t ff_png_pass_ymask[NB_PASSES] = {

     0x80, 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55,
 };
 
 /* minimum x value */

 static const uint8_t ff_png_pass_xmin[NB_PASSES] = {

     0, 4, 0, 2, 0, 1, 0
 };
 
 /* x shift to get row width */

 static const uint8_t ff_png_pass_xshift[NB_PASSES] = {

     3, 3, 2, 2, 1, 1, 0
 };
 

 void *ff_png_zalloc(void *opaque, unsigned int items, unsigned int size)

 {

     return av_mallocz_array(items, size);

 }
 

 void ff_png_zfree(void *opaque, void *ptr)

 {
     av_free(ptr);
 }
 

 int ff_png_get_nb_channels(int color_type)

 {
     int channels;
     channels = 1;
     if ((color_type & (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)) ==
         PNG_COLOR_MASK_COLOR)
         channels = 3;
     if (color_type & PNG_COLOR_MASK_ALPHA)
         channels++;
     return channels;
 }
 
 /* compute the row size of an interleaved pass */

 int ff_png_pass_row_size(int pass, int bits_per_pixel, int width)

 {
     int shift, xmin, pass_width;
 

     xmin = ff_png_pass_xmin[pass];

     if (width <= xmin)
         return 0;

     shift      = ff_png_pass_xshift[pass];

     pass_width = (width - xmin + (1 << shift) - 1) >> shift;
     return (pass_width * bits_per_pixel + 7) >> 3;
 }