/*
  * PNG parser
  * Copyright (c) 2009 Peter Holik
  *
  * 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
  */
 
 /**

  * @file

  * PNG parser
  */
 
 #include "parser.h"

 #include "png.h"

 typedef struct PNGParseContext {

     ParseContext pc;

     uint32_t chunk_pos;           ///< position inside current chunk
     uint32_t chunk_length;        ///< length of the current chunk
     uint32_t remaining_size;      ///< remaining size of the current chunk

 } PNGParseContext;
 
 static int png_parse(AVCodecParserContext *s, AVCodecContext *avctx,
                      const uint8_t **poutbuf, int *poutbuf_size,
                      const uint8_t *buf, int buf_size)
 {
     PNGParseContext *ppc = s->priv_data;
     int next = END_NOT_FOUND;
     int i = 0;
 

     s->pict_type = AV_PICTURE_TYPE_NONE;
 

     *poutbuf_size = 0;
 
     if (!ppc->pc.frame_start_found) {
         uint64_t state64 = ppc->pc.state64;
         for (; i < buf_size; i++) {
             state64 = (state64 << 8) | buf[i];
             if (state64 == PNGSIG || state64 == MNGSIG) {
                 i++;
                 ppc->pc.frame_start_found = 1;
                 break;
             }
         }
         ppc->pc.state64 = state64;

     } else if (ppc->remaining_size) {
         i = FFMIN(ppc->remaining_size, buf_size);
         ppc->remaining_size -= i;
         if (ppc->remaining_size)
             goto flush;
         if (ppc->chunk_pos == -1) {
             next = i;
             goto flush;

         }

     }

     for (; ppc->pc.frame_start_found && i < buf_size; i++) {
         ppc->pc.state = (ppc->pc.state << 8) | buf[i];
         if (ppc->chunk_pos == 3) {

             ppc->chunk_length = ppc->pc.state;

             if (ppc->chunk_length > 0x7fffffff) {

                 ppc->chunk_pos = ppc->pc.frame_start_found = 0;

                 goto flush;
             }
             ppc->chunk_length += 4;

         } else if (ppc->chunk_pos == 7) {

             if (ppc->chunk_length >= buf_size - i)

                 ppc->remaining_size = ppc->chunk_length - buf_size + i + 1;

             if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) {

                 if (ppc->remaining_size)

                     ppc->chunk_pos = -1;

                 else
                     next = ppc->chunk_length + i + 1;
                 break;
             } else {

                 ppc->chunk_pos = 0;

                 if (ppc->remaining_size)
                     break;
                 else
                     i += ppc->chunk_length;
                 continue;
             }
         }

         ppc->chunk_pos++;

     }

 flush:
     if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0)
         return buf_size;
 

     ppc->chunk_pos = ppc->pc.frame_start_found = 0;

 
     *poutbuf      = buf;
     *poutbuf_size = buf_size;
     return next;
 }
 
 AVCodecParser ff_png_parser = {

     .codec_ids      = { AV_CODEC_ID_PNG },

     .priv_data_size = sizeof(PNGParseContext),
     .parser_parse   = png_parse,
     .parser_close   = ff_parse_close,

 };