/*

 * 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 "parser_internal.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;

    *poutbuf = NULL;

    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;

}

const FFCodecParser ff_png_parser = {

    PARSER_CODEC_LIST(AV_CODEC_ID_PNG),

    .priv_data_size = sizeof(PNGParseContext),

    .parse          = png_parse,

    .close          = ff_parse_close,

};