/*

 * Copyright (c) 2004 Roman Shaposhnik

 * Copyright (c) 2008 Alexander Strange (astrange@ithinksw.com)

 *

 * Many thanks to Steven M. Schultz for providing clever ideas and

 * to Michael Niedermayer <michaelni@gmx.at> for writing initial

 * implementation.

 *

 * 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

 * Multithreading support functions

 * @see doc/multithreading.txt

 */

#include "libavutil/attributes.h"

#include "libavutil/thread.h"

#include "avcodec.h"

#include "avcodec_internal.h"

#include "codec_internal.h"

#include "pthread_internal.h"

/**

 * Set the threading algorithms used.

 *

 * Threading requires more than one thread.

 * Frame threading requires entire frames to be passed to the codec,

 * and introduces extra decoding delay, so is incompatible with low_delay.

 *

 * @param avctx The context.

 */

static av_cold void validate_thread_parameters(AVCodecContext *avctx)

{

    int frame_threading_supported = (avctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS)

                                && !(avctx->flags  & AV_CODEC_FLAG_LOW_DELAY)

                                && !(avctx->flags2 & AV_CODEC_FLAG2_CHUNKS);

    if (avctx->thread_count == 1) {

        avctx->active_thread_type = 0;

    } else if (frame_threading_supported && (avctx->thread_type & FF_THREAD_FRAME)) {

        avctx->active_thread_type = FF_THREAD_FRAME;

    } else if (avctx->codec->capabilities & AV_CODEC_CAP_SLICE_THREADS &&

               avctx->thread_type & FF_THREAD_SLICE) {

        avctx->active_thread_type = FF_THREAD_SLICE;

    } else if (!(ffcodec(avctx->codec)->caps_internal & FF_CODEC_CAP_AUTO_THREADS)) {

        avctx->thread_count       = 1;

        avctx->active_thread_type = 0;

    }

    if (avctx->thread_count > MAX_AUTO_THREADS)

        av_log(avctx, AV_LOG_WARNING,

               "Application has requested %d threads. Using a thread count greater than %d is not recommended.\n",

               avctx->thread_count, MAX_AUTO_THREADS);

}

av_cold int ff_thread_init(AVCodecContext *avctx)

{

    validate_thread_parameters(avctx);

    if (avctx->active_thread_type&FF_THREAD_SLICE)

        return ff_slice_thread_init(avctx);

    else if (avctx->active_thread_type&FF_THREAD_FRAME)

        return ff_frame_thread_init(avctx);

    return 0;

}

av_cold void ff_thread_free(AVCodecContext *avctx)

{

    if (avctx->active_thread_type&FF_THREAD_FRAME)

        ff_frame_thread_free(avctx, avctx->thread_count);

    else

        ff_slice_thread_free(avctx);

}

av_cold void ff_pthread_free(void *obj, const unsigned offsets[])

{

    unsigned cnt = *(unsigned*)((char*)obj + offsets[0]);

    const unsigned *cur_offset = offsets;

    *(unsigned*)((char*)obj + offsets[0]) = 0;

    for (; *(++cur_offset) != THREAD_SENTINEL && cnt; cnt--)

        pthread_mutex_destroy((pthread_mutex_t*)((char*)obj + *cur_offset));

    for (; *(++cur_offset) != THREAD_SENTINEL && cnt; cnt--)

        pthread_cond_destroy ((pthread_cond_t *)((char*)obj + *cur_offset));

}

av_cold int ff_pthread_init(void *obj, const unsigned offsets[])

{

    const unsigned *cur_offset = offsets;

    unsigned cnt = 0;

    int err;

#define PTHREAD_INIT_LOOP(type)                                               \

    for (; *(++cur_offset) != THREAD_SENTINEL; cnt++) {                       \

        pthread_ ## type ## _t *dst = (void*)((char*)obj + *cur_offset);      \

        err = pthread_ ## type ## _init(dst, NULL);                           \

        if (err) {                                                            \

            err = AVERROR(err);                                               \

            goto fail;                                                        \

        }                                                                     \

    }

    PTHREAD_INIT_LOOP(mutex)

    PTHREAD_INIT_LOOP(cond)

fail:

    *(unsigned*)((char*)obj + offsets[0]) = cnt;

    return err;

}