/*
  * H261 parser
  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
  * Copyright (c) 2004 Maarten Daniels
  *
  * 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 libavcodec/h261_parser.c

  * h261codec.
  */
 
 #include "parser.h"
 
 
 static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
     int vop_found, i, j;
     uint32_t state;
 
     vop_found= pc->frame_start_found;
     state= pc->state;
 
     for(i=0; i<buf_size && !vop_found; i++){
         state= (state<<8) | buf[i];
         for(j=0; j<8; j++){

             if(((state>>j)&0xFFFFF0) == 0x000100){

                 vop_found=1;
                 break;
             }
         }
     }
     if(vop_found){
         for(; i<buf_size; i++){
             state= (state<<8) | buf[i];
             for(j=0; j<8; j++){

                 if(((state>>j)&0xFFFFF0) == 0x000100){

                     pc->frame_start_found=0;

                     pc->state= (state>>(3*8))+0xFF00;
                     return i-2;

                 }
             }
         }
     }
 
     pc->frame_start_found= vop_found;
     pc->state= state;
     return END_NOT_FOUND;
 }
 
 static int h261_parse(AVCodecParserContext *s,
                       AVCodecContext *avctx,

                       const uint8_t **poutbuf, int *poutbuf_size,

                       const uint8_t *buf, int buf_size)
 {
     ParseContext *pc = s->priv_data;
     int next;
 
     next= h261_find_frame_end(pc,avctx, buf, buf_size);

     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

         *poutbuf = NULL;
         *poutbuf_size = 0;
         return buf_size;
     }

     *poutbuf = buf;

     *poutbuf_size = buf_size;
     return next;
 }
 
 AVCodecParser h261_parser = {
     { CODEC_ID_H261 },
     sizeof(ParseContext),
     NULL,
     h261_parse,
     ff_parse_close,
 };