port_fifo.c

一个有限状态机的实现源代码。C语言实现。

/*
  The oSIP library implements the Session Initiation Protocol (SIP -rfc2543-)
  Copyright (C) 2001  Aymeric MOIZARD [e-mail]
  
  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 2.1 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <stdlib.h>
#include <stdio.h>

#include <osip/fifo.h>
#include <osip/port.h>


/* always use this method to initiate fifo_t.
*/
void
fifo_init(fifo_t *ff)
{
#ifdef OSIP_MT
  ff->qislocked = smutex_init();
  /*INIT SEMA TO BLOCK ON GET() WHEN QUEUE IS EMPTY */
  ff->qisempty = ssem_init( 0 );
#endif
  ff->queue = (list_t *)smalloc(sizeof(list_t));
  list_init(ff->queue);
  /* ff->nb_elt = 0; */
  ff->etat   = vide;
}

int
fifo_add(fifo_t *ff , void *el)
{
#ifdef OSIP_MT
  smutex_lock(ff->qislocked);
#endif

  if (ff->etat != plein)
    {
      /* ff->nb_elt++; */
      list_add(ff->queue,el,-1); /* insert at end of queue */
    }
  else
    {
      fprintf(stdout,"<port_fifo.c> (fifo_t:%x) WARNING STACK IS OVERLOADED\n",(int)ff);
#ifdef OSIP_MT
      smutex_unlock(ff->qislocked);
#endif
      return -1;      /* stack is full */
    }
  /* if (ff->nb_elt >= MAX_LEN) */
  if (list_size(ff->queue) >= MAX_LEN)
    ff->etat = plein;
  else
    ff->etat = ok;

#ifdef OSIP_MT
  ssem_post(ff->qisempty);
  smutex_unlock(ff->qislocked);
#endif
  return 0;
}

#ifdef OSIP_MT

void*
fifo_get(fifo_t *ff)
{
  void *el;
  ssem_wait(ff->qisempty);
  smutex_lock(ff->qislocked);

  if (ff->etat != vide)
    {
      el = list_get(ff->queue,0);
      list_remove(ff->queue,0);
      /* ff->nb_elt--; */
    }
  else
    {
    fprintf(stdout,"<port_fifo.c>  (fifo_t:%x) No element available?\n",(int)ff);
    smutex_unlock(ff->qislocked);
    return 0;      /* pile vide */
    }
  /* if (ff->nb_elt <= 0) */
  if (list_size(ff->queue) <= 0)
    ff->etat = vide;
  else
    ff->etat = ok;

  smutex_unlock(ff->qislocked);
  return el;
}

#endif

void *
fifo_tryget(fifo_t *ff)
{
  void *el;

#ifdef OSIP_MT
  if (0>ssem_trywait(ff->qisempty))
    {/* no elements... */
      return NULL;
    }
  smutex_lock(ff->qislocked);
#else
  if (ff->etat == vide)
    return NULL;
#endif

  if (ff->etat != vide)
    {
      el = list_get(ff->queue,0);
      list_remove(ff->queue,0);
      /* ff->nb_elt--; */
    }
#ifdef OSIP_MT
  else
    { /* this case MUST never happen... */
    fprintf(stdout,"<port_fifo.c>  (fifo_t:%x) No element available?\n",(int)ff);
    smutex_unlock(ff->qislocked);
    return 0;
    }
#endif

  /* if (ff->nb_elt <= 0) */
  if (list_size(ff->queue) <= 0)
    ff->etat = vide;
  else
    ff->etat = ok;

#ifdef OSIP_MT
  smutex_unlock(ff->qislocked);
#endif
  return el;
}

void
fifo_free(fifo_t *ff)
{
#ifdef OSIP_MT
  smutex_destroy(ff->qislocked);
#ifndef __VXWORKS_OS__
  sfree(ff->qislocked);
#endif 
  /* seems that pthread_mutex_destroy does not free space by itself */
  ssem_destroy(ff->qisempty);
#ifndef __VXWORKS_OS__
  sfree(ff->qisempty);
#endif 
#endif
  sfree(ff->queue);
}