/*
 * 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
 * Slice multithreading support functions
 * @see doc/multithreading.txt
 */

#include "avcodec.h"
#include "codec_internal.h"
#include "internal.h"
#include "pthread_internal.h"
#include "thread.h"

#include "libavutil/attributes.h"
#include "libavutil/cpu.h"
#include "libavutil/macros.h"
#include "libavutil/mem.h"
#include "libavutil/slicethread.h"

typedef int (action_func)(AVCodecContext *c, void *arg);
typedef int (action_func2)(AVCodecContext *c, void *arg, int jobnr, int threadnr);
typedef int (main_func)(AVCodecContext *c);

typedef struct SliceThreadContext {
    AVSliceThread *thread;
    action_func *func;
    action_func2 *func2;
    main_func *mainfunc;
    void *args;
    int *rets;
    int job_size;
} SliceThreadContext;

static int main_function(void *priv) {
    AVCodecContext *avctx = priv;
    SliceThreadContext *c = avctx->internal->thread_ctx;
    c->mainfunc(avctx);
    return 0;
}

static int worker_func(void *priv, int jobnr, int threadnr, int nb_jobs, int nb_threads)
{
    AVCodecContext *avctx = priv;
    SliceThreadContext *c = avctx->internal->thread_ctx;
    int ret;

    ret = c->func ? c->func(avctx, (char *)c->args + c->job_size * jobnr)
                  : c->func2(avctx, c->args, jobnr, threadnr);
    if (c->rets)
        c->rets[jobnr] = ret;

    return 0;
}

av_cold void ff_slice_thread_free(AVCodecContext *avctx)
{
    SliceThreadContext *c = avctx->internal->thread_ctx;

    avpriv_slicethread_free(&c->thread);

    av_freep(&avctx->internal->thread_ctx);
}

static int thread_execute(AVCodecContext *avctx, action_func* func, void *arg, int *ret, int job_count, int job_size)
{
    SliceThreadContext *c = avctx->internal->thread_ctx;

    if (!(avctx->active_thread_type&FF_THREAD_SLICE) || avctx->thread_count <= 1)
        return avcodec_default_execute(avctx, func, arg, ret, job_count, job_size);

    if (job_count <= 0)
        return 0;

    c->job_size = job_size;
    c->args = arg;
    c->func = func;
    c->rets = ret;

    avpriv_slicethread_execute2(c->thread, job_count, !!c->mainfunc  );
    return 0;
}

static int thread_execute2(AVCodecContext *avctx, action_func2* func2, void *arg, int *ret, int job_count)
{
    SliceThreadContext *c = avctx->internal->thread_ctx;
    c->func2 = func2;
    return thread_execute(avctx, NULL, arg, ret, job_count, 0);
}

int ff_slice_thread_execute_with_mainfunc(AVCodecContext *avctx, action_func2* func2, main_func *mainfunc, void *arg, int *ret, int job_count)
{
    SliceThreadContext *c = avctx->internal->thread_ctx;
    c->func2 = func2;
    c->mainfunc = mainfunc;
    return thread_execute(avctx, NULL, arg, ret, job_count, 0);
}

av_cold int ff_slice_thread_init(AVCodecContext *avctx)
{
    SliceThreadContext *c;
    int thread_count = avctx->thread_count;
    int (*mainfunc)(void *);

    if (!thread_count) {
        int nb_cpus = av_cpu_count();
        if  (avctx->height)
            nb_cpus = FFMIN(nb_cpus, (avctx->height+15)/16);
        // use number of cores + 1 as thread count if there is more than one
        if (nb_cpus > 1)
            thread_count = avctx->thread_count = FFMIN(nb_cpus + 1, MAX_AUTO_THREADS);
        else
            thread_count = avctx->thread_count = 1;
    }

    if (thread_count <= 1) {
        avctx->active_thread_type = 0;
        return 0;
    }

    avctx->internal->thread_ctx = c = av_mallocz(sizeof(*c));
    if (!c)
        return AVERROR(ENOMEM);
    mainfunc = ffcodec(avctx->codec)->caps_internal & FF_CODEC_CAP_SLICE_THREAD_HAS_MF ? &main_function : NULL;
    thread_count = avpriv_slicethread_create2(&c->thread, avctx, worker_func,
                                              mainfunc, thread_count);
    if (thread_count <= 1) {
        ff_slice_thread_free(avctx);
        avctx->thread_count = 1;
        avctx->active_thread_type = 0;
        return thread_count < 0 ? thread_count : 0;
    }
    avctx->thread_count = thread_count;

    avctx->execute = thread_execute;
    avctx->execute2 = thread_execute2;
    return 0;
}
