text: /*
   * Copyright (c) 2004 François Revol <revol@free.fr>
   *
   * 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
   */
  //#define DEBUG
  
  #include "avcodec.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 do not 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);
  }
  
  static int avcodec_thread_execute(AVCodecContext *s, int (*func)(AVCodecContext *c2, void *arg2),void *arg, int *ret, int count, int size){
      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= (char*)arg + i*size;
          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;
  
      if (thread_count <= 1)
          return 0;
  
      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);
  }
  
  
  
  