FFmpeg/libavcodec/pnm_parser.c

/*
 * PNM image parser
 * Copyright (c) 2002, 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 "parser.h" //for ParseContext
#include "pnm.h"


static int pnm_parse(AVCodecParserContext *s,
                           AVCodecContext *avctx,
                           const uint8_t **poutbuf, int *poutbuf_size,
                           const uint8_t *buf, int buf_size)
{
    ParseContext *pc = s->priv_data;
    PNMContext pnmctx;
    int next;

    for(; pc->overread>0; pc->overread--){
        pc->buffer[pc->index++]= pc->buffer[pc->overread_index++];
    }
retry:
    if(pc->index){
        pnmctx.bytestream_start=
        pnmctx.bytestream= pc->buffer;
        pnmctx.bytestream_end= pc->buffer + pc->index;
    }else{
        pnmctx.bytestream_start=
        pnmctx.bytestream= (uint8_t *) buf; /* casts avoid warnings */
        pnmctx.bytestream_end= (uint8_t *) buf + buf_size;
    }
    if(ff_pnm_decode_header(avctx, &pnmctx) < 0){
        if(pnmctx.bytestream < pnmctx.bytestream_end){
            if(pc->index){
                pc->index=0;
            }else{
                buf++;
                buf_size--;
            }
            goto retry;
        }
#if 0
        if(pc->index && pc->index*2 + FF_INPUT_BUFFER_PADDING_SIZE < pc->buffer_size && buf_size > pc->index){
            memcpy(pc->buffer + pc->index, buf, pc->index);
            pc->index += pc->index;
            buf += pc->index;
            buf_size -= pc->index;
            goto retry;
        }
#endif
        next= END_NOT_FOUND;
    }else{
        next= pnmctx.bytestream - pnmctx.bytestream_start
            + avpicture_get_size(avctx->pix_fmt, avctx->width, avctx->height);
        if(pnmctx.bytestream_start!=buf)
            next-= pc->index;
        if(next > buf_size)
            next= END_NOT_FOUND;
    }

    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 pnm_parser = {
    { CODEC_ID_PGM, CODEC_ID_PGMYUV, CODEC_ID_PPM, CODEC_ID_PBM, CODEC_ID_PAM},
    sizeof(ParseContext),
    NULL,
    pnm_parse,
    ff_parse_close,
};