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

 * vlc_timestamp_helper.h : timestamp handling helpers

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

 * Copyright (C) 2014 VLC authors and VideoLAN

 *

 * Authors: Felix Abecassis <felix.abecassis@gmail.com>

 *

 * 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_TIMESTAMP_H

#define VLC_TIMESTAMP_H 1

#include <vlc_tick.h>

/* Implementation of a circular buffer of timestamps with overwriting

 * of older values. MediaCodec has only one type of timestamp, if a

 * block has no PTS, we send the DTS instead. Some hardware decoders

 * cannot cope with this situation and output the frames in the wrong

 * order. As a workaround in this case, we use a FIFO of timestamps in

 * order to remember which input packets had no PTS.  Since an

 * hardware decoder can silently drop frames, this might cause a

 * growing desynchronization with the actual timestamp. Thus the

 * circular buffer has a limited size and will overwrite older values.

 */

typedef struct

{

    uint32_t          begin;

    uint32_t          size;

    uint32_t          capacity;

    vlc_tick_t        *buffer;

} timestamp_fifo_t;

static inline timestamp_fifo_t *timestamp_FifoNew(uint32_t capacity)

{

    timestamp_fifo_t *fifo = (timestamp_fifo_t *)calloc(1, sizeof(*fifo));

    if (!fifo)

        return NULL;

    fifo->buffer = (vlc_tick_t*)vlc_alloc(capacity, sizeof(*fifo->buffer));

    if (!fifo->buffer) {

        free(fifo);

        return NULL;

    }

    fifo->capacity = capacity;

    return fifo;

}

static inline void timestamp_FifoRelease(timestamp_fifo_t *fifo)

{

    free(fifo->buffer);

    free(fifo);

}

static inline bool timestamp_FifoIsEmpty(timestamp_fifo_t *fifo)

{

    return fifo->size == 0;

}

static inline bool timestamp_FifoIsFull(timestamp_fifo_t *fifo)

{

    return fifo->size == fifo->capacity;

}

static inline void timestamp_FifoEmpty(timestamp_fifo_t *fifo)

{

    fifo->size = 0;

}

static inline void timestamp_FifoPut(timestamp_fifo_t *fifo, vlc_tick_t ts)

{

    uint32_t end = (fifo->begin + fifo->size) % fifo->capacity;

    fifo->buffer[end] = ts;

    if (!timestamp_FifoIsFull(fifo))

        fifo->size += 1;

    else

        fifo->begin = (fifo->begin + 1) % fifo->capacity;

}

static inline vlc_tick_t timestamp_FifoGet(timestamp_fifo_t *fifo)

{

    if (timestamp_FifoIsEmpty(fifo))

        return VLC_TICK_INVALID;

    vlc_tick_t result = fifo->buffer[fifo->begin];

    fifo->begin = (fifo->begin + 1) % fifo->capacity;

    fifo->size -= 1;

    return result;

}

#endif