bitpack.cpp

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 ***** */ 

#include "bitpack.h"

#include "hlxclib/string.h"
#include "hxassert.h"
#include "bitstream.h"

static const UINT32 z_mask[9] = {0x00, 0x01, 0x03, 0x07, 0x0f,
				 0x1f, 0x3f, 0x7f, 0xff};
BitPacker::BitPacker(UINT8* pBuf, ULONG32 ulBufSize) :
    m_pBuf(pBuf),
    m_ulBufSize(ulBufSize),
    m_pCur(pBuf),
    m_bitsLeft(8)
{
    ::memset(m_pCur, 0, ulBufSize);
}

void BitPacker::PackBits(UINT32 bits, ULONG32 bitCount)
{
    HX_ASSERT(bitCount <= 32);

    if (bitCount > m_bitsLeft)
    {
	// Finish up this byte
	bitCount -= m_bitsLeft;
	*m_pCur++ |= (UINT8)((bits >> bitCount) & z_mask[m_bitsLeft]);

	m_bitsLeft = 8;

	while(bitCount >= 8)
	{
	    bitCount -= 8;
	    *m_pCur++ = (UINT8)((bits >> bitCount) & 0xff);
	}
    }

    if (bitCount)
    {
    	m_bitsLeft -= bitCount;
	*m_pCur |= (bits & z_mask[bitCount]) << m_bitsLeft;
	
	if (m_bitsLeft == 0)
	{
	    m_bitsLeft = 8;
	    m_pCur++;
	}
    }
}

void BitPacker::PackBits(const UINT8* pBuf, ULONG32 bitCount,
			 ULONG32 ulStartOffset)
{
    // Reference implementation
    Bitstream bs;
    bs.SetBuffer(pBuf);

    bs.GetBits(ulStartOffset);

    while(bitCount)
    {
	int bits = (bitCount > 8) ? 8 : bitCount;
	PackBits(bs.GetBits(bits), bits);
	bitCount -= bits;
    }
}

UINT32 BitPacker::ByteAlign()
{
  UINT32 bits = m_bitsLeft & 7 ;
  PackBits(0, bits) ;
  return bits ;
}

ULONG32 BitPacker::BytesUsed() const
{
    return (m_pCur - m_pBuf);
}