cringbuf.h

著名的 helix realplayer 基于手机 symbian 系统的 播放器全套源代码

/* ***** BEGIN LICENSE BLOCK ***** 
 * Version: RCSL 1.0/RPSL 1.0 
 *  
 * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 
 *      
 * The contents of this file, and the files included with this file, are 
 * subject to the current version of the RealNetworks Public Source License 
 * Version 1.0 (the "RPSL") available at 
 * http://www.helixcommunity.org/content/rpsl unless you have licensed 
 * the file under the RealNetworks Community Source License Version 1.0 
 * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, 
 * in which case the RCSL will apply. You may also obtain the license terms 
 * directly from RealNetworks.  You may not use this file except in 
 * compliance with the RPSL or, if you have a valid RCSL with RealNetworks 
 * applicable to this file, the RCSL.  Please see the applicable RPSL or 
 * RCSL for the rights, obligations and limitations governing use of the 
 * contents of the file.  
 *  
 * This file is part of the Helix DNA Technology. RealNetworks is the 
 * developer of the Original Code and owns the copyrights in the portions 
 * it created. 
 *  
 * This file, and the files included with this file, is distributed and made 
 * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 
 * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES, 
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS 
 * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 
 * 
 * Technology Compatibility Kit Test Suite(s) Location: 
 *    http://www.helixcommunity.org/content/tck 
 * 
 * Contributor(s): 
 *  
 * ***** END LICENSE BLOCK ***** */ 

#ifndef _CRINGBUF_
#define _CRINGBUF_

/****************************************************************************
 *  Includes
 */
#define RNGBF_FULL_SIZE	    0x7FFFFFFF


/****************************************************************************
 *  Includes
 */
#include "hxtypes.h"
#include "hxresult.h"
#include "hxassert.h"


/****************************************************************************
 *  CRingBuffer
 */
class CRingBuffer
{
public:
    CRingBuffer(ULONG32 ulSize)
	: m_pDataStart(NULL)
	, m_pDataEnd(NULL)
	, m_pHead(NULL)
	, m_pTail(NULL)
	, m_ulSize(ulSize)
	, m_lMaxCount((LONG32) ulSize)
    {
	HX_ASSERT(ulSize);

	m_pDataStart = new void* [ulSize + 1];

	HX_ASSERT(m_pDataStart);

	m_pDataEnd = &(m_pDataStart[ulSize]);

	m_pHead = m_pDataStart;
	m_pTail = m_pHead;
    }

    ~CRingBuffer()
    {
	delete [] m_pDataStart;
    }

    BOOL Put(void* pData)
    {	
	if (Count() < m_lMaxCount)
	{
	    *m_pHead = pData;
	    m_pHead = Advance(m_pHead);
	    
	    return TRUE;
	}

	return FALSE;
    }

    void* Get(void)
    {
	void* pData = NULL;

	if (m_pTail != m_pHead)
	{
	    pData = *m_pTail;
	    m_pTail = Advance(m_pTail);
	}

	return pData;
    }

    void* Peek(void)
    {
	void* pData = NULL;

	if (m_pTail != m_pHead)
	{
	    pData = *m_pTail;
	}

	return pData;
    }

    LONG32 Count(void)
    {
	LONG32 lCount = m_pHead - m_pTail;

	if (lCount < 0)
	{
	    lCount += (m_ulSize + 1);
	}

	return lCount;
    }

    BOOL IsFull(void)
    {
	return (Count() >= m_lMaxCount);
    }

    void SetMaxCount(LONG32 lMaxCount)
    {
	if (lMaxCount <= ((LONG32) m_ulSize))
	{
	    m_lMaxCount = lMaxCount;
	}
	else
	{
	    m_lMaxCount = (LONG32) m_ulSize;
	}
    }

    LONG32 MaxCount(void)
    {
	return m_lMaxCount;
    }

    ULONG32 Size(void)
    {
	return m_ulSize;
    }

private:
    void** Advance(void** pDataPtr)
    {
	if (pDataPtr != m_pDataEnd)
	{
	    pDataPtr++;
	}
	else
	{
	    pDataPtr = m_pDataStart;
	}

	return pDataPtr;
    }

    ULONG32 m_ulSize;
    LONG32 m_lMaxCount;
    void** m_pDataStart;
    void** m_pDataEnd;
    void** m_pHead;
    void** m_pTail;
};

#endif	// _CRINGBUF_