msg_queue.cpp

MPEG-4编解码的实现(包括MPEG4视音频编解码)

/*
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is MPEG4IP.
 * 
 * The Initial Developer of the Original Code is Cisco Systems Inc.
 * Portions created by Cisco Systems Inc. are
 * Copyright (C) Cisco Systems Inc. 2000, 2001.  All Rights Reserved.
 * 
 * Contributor(s): 
 *              Bill May        [e-mail]
 */
/*
 * msg_queue.cpp - generic class to send/receive messages.  Uses SDL mutexs
 * to protect queues
 */
#include <string.h>
#include "msg_queue.h"

/*****************************************************************************
 * CMsg class methods.  Defines information about a single message
 *****************************************************************************/
CMsg::CMsg (uint32_t value, unsigned char *msg, uint32_t msg_len)
{
  m_value = value;
  m_msg_len = 0;
  m_has_param = 0;
  m_next = NULL;

  if (msg_len) {
    m_msg = (unsigned char *)malloc(msg_len);
	if (m_msg) {
		memcpy(m_msg, msg, msg_len);
		m_msg_len = msg_len;
	}
  } else {
	m_msg = msg;
  }
}

CMsg::CMsg (uint32_t value, uint32_t param)
{
	m_value = value;
	m_msg_len = 0;
	m_has_param = 1;
	m_param = param;
}

CMsg::~CMsg (void) 
{
  if (m_msg_len) {
    free(m_msg);
    m_msg = NULL;
  }
}

const unsigned char *CMsg::get_message (uint32_t &len)
{
  len = m_msg_len;
  return (m_msg);
}

/*****************************************************************************
 * CMsgQueue class methods.  Defines information about a message queue
 *****************************************************************************/
CMsgQueue::CMsgQueue(void)
{
  m_msg_queue = NULL;
  m_msg_queue_mutex = SDL_CreateMutex();
}

CMsgQueue::~CMsgQueue (void) 
{
  CMsg *p;
  SDL_mutexP(m_msg_queue_mutex);
  while (m_msg_queue != NULL) {
    p = m_msg_queue->get_next();
    delete m_msg_queue;
    m_msg_queue = p;
  }
  SDL_DestroyMutex(m_msg_queue_mutex);
  m_msg_queue_mutex = NULL;
}

int CMsgQueue::send_message (uint32_t msgval, 
			     unsigned char *msg, 
			     uint32_t msg_len, 
			     SDL_sem *sem)
{
  CMsg *newmsg = new CMsg(msgval, msg, msg_len);

  if (newmsg == NULL) 
    return (-1);
  return (send_message(newmsg, sem));
}

int CMsgQueue::send_message (uint32_t msgval, uint32_t param, SDL_sem *sem)
{
	CMsg *newmsg = new CMsg(msgval, param);

	if (newmsg == NULL) return -1;

	return (send_message(newmsg, sem));
}

int CMsgQueue::send_message(CMsg *newmsg, SDL_sem *sem)
{

  SDL_mutexP(m_msg_queue_mutex);
  if (m_msg_queue == NULL) {
    m_msg_queue = newmsg;
  } else {
    CMsg *p = m_msg_queue;
    while (p->get_next() != NULL) p = p->get_next();
    p->set_next(newmsg);
  }
  SDL_mutexV(m_msg_queue_mutex);
  if (sem != NULL) {
    SDL_SemPost(sem);
  }
  return (0);
}

CMsg *CMsgQueue::get_message (void) 
{
  CMsg *ret;

  if (m_msg_queue == NULL) 
    return(NULL);

  SDL_mutexP(m_msg_queue_mutex);
  if (m_msg_queue == NULL) 
    ret = NULL;
  else {
    ret = m_msg_queue;
    m_msg_queue = ret->get_next();
  }
  SDL_mutexV(m_msg_queue_mutex);
  if (ret) {
    ret->set_next(NULL);
  }
  return (ret);
}
  
/* end file msg_queue.cpp */