PeerStreamer

/*

 * Copyright (c) 2004 François Revol <revol@free.fr>

 *

 * This library 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 of the License, or (at your option) any later version.

 *

 * This library 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 library; if not, write to the Free Software

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

 *

 */

//#define DEBUG

#include "avcodec.h"

#include "common.h"

#include <OS.h>

typedef struct ThreadContext{

    AVCodecContext *avctx;

    thread_id thread;

    sem_id work_sem;

    sem_id done_sem;

    int (*func)(AVCodecContext *c, void *arg);

    void *arg;

    int ret;

}ThreadContext;

// it's odd Be never patented that :D

struct benaphore {

        vint32 atom;

        sem_id sem;

};

static inline int lock_ben(struct benaphore *ben)

{

        if (atomic_add(&ben->atom, 1) > 0)

                return acquire_sem(ben->sem);

        return B_OK;

}

static inline int unlock_ben(struct benaphore *ben)

{

        if (atomic_add(&ben->atom, -1) > 1)

                return release_sem(ben->sem);

        return B_OK;

}

static struct benaphore av_thread_lib_ben;

static int32 ff_thread_func(void *v){

    ThreadContext *c= v;

    for(;;){

//printf("thread_func %X enter wait\n", (int)v); fflush(stdout);

        acquire_sem(c->work_sem);

//printf("thread_func %X after wait (func=%X)\n", (int)v, (int)c->func); fflush(stdout);

        if(c->func)

            c->ret= c->func(c->avctx, c->arg);

        else

            return 0;

//printf("thread_func %X signal complete\n", (int)v); fflush(stdout);

        release_sem(c->done_sem);

    }

    return B_OK;

}

/**

 * free what has been allocated by avcodec_thread_init().

 * must be called after decoding has finished, especially dont call while avcodec_thread_execute() is running

 */

void avcodec_thread_free(AVCodecContext *s){

    ThreadContext *c= s->thread_opaque;

    int i;

    int32 ret;

    for(i=0; i<s->thread_count; i++){

        c[i].func= NULL;

        release_sem(c[i].work_sem);

        wait_for_thread(c[i].thread, &ret);

        if(c[i].work_sem > B_OK) delete_sem(c[i].work_sem);

        if(c[i].done_sem > B_OK) delete_sem(c[i].done_sem);

    }

    av_freep(&s->thread_opaque);

}

int avcodec_thread_execute(AVCodecContext *s, int (*func)(AVCodecContext *c2, void *arg2),void **arg, int *ret, int count){

    ThreadContext *c= s->thread_opaque;

    int i;

    assert(s == c->avctx);

    assert(count <= s->thread_count);

    /* note, we can be certain that this is not called with the same AVCodecContext by different threads at the same time */

    for(i=0; i<count; i++){

        c[i].arg= arg[i];

        c[i].func= func;

        c[i].ret= 12345;

        release_sem(c[i].work_sem);

    }

    for(i=0; i<count; i++){

        acquire_sem(c[i].done_sem);

        c[i].func= NULL;

        if(ret) ret[i]= c[i].ret;

    }

    return 0;

}

int avcodec_thread_init(AVCodecContext *s, int thread_count){

    int i;

    ThreadContext *c;

    s->thread_count= thread_count;

    assert(!s->thread_opaque);

    c= av_mallocz(sizeof(ThreadContext)*thread_count);

    s->thread_opaque= c;

    for(i=0; i<thread_count; i++){

//printf("init semaphors %d\n", i); fflush(stdout);

        c[i].avctx= s;

        if((c[i].work_sem = create_sem(0, "ff work sem")) < B_OK)

            goto fail;

        if((c[i].done_sem = create_sem(0, "ff done sem")) < B_OK)

            goto fail;

//printf("create thread %d\n", i); fflush(stdout);

        c[i].thread = spawn_thread(ff_thread_func, "libavcodec thread", B_LOW_PRIORITY, &c[i] );

        if( c[i].thread < B_OK ) goto fail;

        resume_thread(c[i].thread );

    }

//printf("init done\n"); fflush(stdout);

    s->execute= avcodec_thread_execute;

    return 0;

fail:

    avcodec_thread_free(s);

    return -1;

}

/* provide a mean to serialize calls to avcodec_*() for thread safety. */

int avcodec_thread_lock_lib(void)

{

        return lock_ben(&av_thread_lib_ben);

}

int avcodec_thread_unlock_lib(void)

{

        return unlock_ben(&av_thread_lib_ben);

}

/* our versions of _init and _fini (which are called by those actually from crt.o) */

void initialize_after(void)

{

        av_thread_lib_ben.atom = 0;

        av_thread_lib_ben.sem = create_sem(0, "libavcodec benaphore");

}

void uninitialize_before(void)

{

        delete_sem(av_thread_lib_ben.sem);

}