semaphore.cpp

FreeAMP(MP3播放)程序源代码-用来研究MP3解码

/*____________________________________________________________________________
	
	FreeAmp - The Free MP3 Player

	Portions Copyright (C) 1998-1999 EMusic.com

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program 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 General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	
	$Id: semaphore.cpp,v 1.7 2000/05/04 11:28:31 robert Exp $
____________________________________________________________________________*/

#include <limits.h>

#include "semaphore.h"

Semaphore::Semaphore(int cnt) {
    m_count = cnt;
    m_sem = CreateSemaphore(NULL, 
		    				cnt,
							LONG_MAX,
							""); 
}

Semaphore::~Semaphore() {
   CloseHandle(m_sem);
}

bool Semaphore::Wait(int ms) 
{	
   if (ms > 0)
   {
	   if (WaitForSingleObject(m_sem, ms) == WAIT_TIMEOUT)
          return false;

      return true;
   }

	WaitForSingleObject(m_sem, INFINITE);	
   return true;
}

void Semaphore::Signal() {
	long dummy;
    ReleaseSemaphore(	m_sem,
    					1,
    					&dummy);
}