/*****************************************************************************

 * av1_unpack.h: AV1 samples expander

 *****************************************************************************

 * Copyright (C) 2018 VideoLabs, VLC authors and VideoLAN

 *

 * This program 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.

 *

 * This program 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 this program; if not, write to the Free Software Foundation,

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

 *****************************************************************************/

#ifndef VLC_AV1_UNPACK_H

#define VLC_AV1_UNPACK_H

#include "../packetizer/av1_obu.h"

#include <vlc_common.h>

#include <vlc_block.h>

static inline uint8_t leb128_expected(uint32_t v)

{

    if     (v < (1U << 7))  return 1;

    else if(v < (1U << 14)) return 2;

    else if(v < (1U << 21)) return 3;

    else if(v < (1U << 28)) return 4;

    else                    return 5;

}

static inline void leb128_write(uint32_t v, uint8_t *p)

{

    for(;;)

    {

        *p = v & 0x7F;

        v >>= 7;

        if(v == 0)

            break;

        *p++ |= 0x80;

    }

}

static inline block_t * AV1_Unpack_Sample_ExpandSize(block_t *p_block)

{

    AV1_OBU_iterator_ctx_t ctx;

    AV1_OBU_iterator_init(&ctx, p_block->p_buffer, p_block->i_buffer);

    const uint8_t *p_obu = NULL; size_t i_obu;

    while(AV1_OBU_iterate_next(&ctx, &p_obu, &i_obu))

    {

        if(AV1_OBUHasSizeField(p_obu))

            continue;

        const uint8_t i_header = 1 + AV1_OBUHasExtensionField(p_obu);

        if(i_header > i_obu)

            break;

        const uint8_t i_sizelen = leb128_expected(i_obu - i_header);

        const size_t i_obu_offset = p_obu - p_block->p_buffer;

        /* Make room for i_sizelen after header */

        if(2 * (i_obu_offset + i_header) + i_sizelen < p_block->i_buffer)

        {

            /* move data to the left */

            p_block = block_Realloc(p_block, i_sizelen, p_block->i_buffer);

            if(p_block)

                memmove(p_block->p_buffer, &p_block->p_buffer[i_sizelen],

                        i_obu_offset + i_header);

        }

        else

        {

            /* move data to the right */

            p_block = block_Realloc(p_block, 0, p_block->i_buffer + i_sizelen);

            if(p_block)

            {

                const size_t i_off = i_obu_offset + i_header;

                memmove(&p_block->p_buffer[i_off + i_sizelen], &p_block->p_buffer[i_off],

                        p_block->i_buffer - i_off - i_sizelen);

            }

        }

        if(likely(p_block))

        {

            leb128_write(i_obu - i_header, &p_block->p_buffer[i_obu_offset + i_header]);

            p_block->p_buffer[i_obu_offset] |= 0x02;

        }

        break;

    }

    return p_block;

}

/*

    Restores TD OBU and last size field from MP4/MKV sample format

    to full AV1 low overhead format.

    AV1 ISOBMFF Mapping 2.4

    https://aomediacodec.github.io/av1-isobmff/#sampleformat

    Matroska/WebM

    https://github.com/Matroska-Org/matroska-specification/blob/master/codec/av1.md

*/

static inline block_t * AV1_Unpack_Sample(block_t *p_block)

{

    /* Restore last size field if missing */

    p_block = AV1_Unpack_Sample_ExpandSize(p_block);

    /* Reinsert removed TU: See av1-isobmff 2.4 */

    if(p_block &&

       (p_block->p_buffer[0] & 0x81) == 0 && /* reserved flags */

       (p_block->p_buffer[0] & 0x7A) != 0x12) /* no TEMPORAL_DELIMITER */

    {

        p_block = block_Realloc(p_block, 2, p_block->i_buffer);

        if(p_block)

        {

            p_block->p_buffer[0] = 0x12;

            p_block->p_buffer[1] = 0x00;

        }

    }

    return p_block;

}

#endif