BitStream.h

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/*
 * The Progressive Graphics File; http://www.libpgf.org
 * 
 * $Date: 2006-06-04 22:05:59 +0200 (So, 04 Jun 2006) $
 * $Revision: 229 $
 * 
 * This file Copyright (C) 2006 xeraina GmbH, Switzerland
 * 
 * This program 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 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

 
#ifndef PGF_BITSTREAM_H
#define PGF_BITSTREAM_H
 
#include "PGFtypes.h"
 
// constants
//static const WordWidth = 32;
//static const WordWidthLog = 5;
static const UINT32 Filled = 0xFFFFFFFF;

#define MAKEU64(a, b) ((UINT64) (((UINT32) (a)) | ((UINT64) ((UINT32) (b))) << 32)) 
 
// these procedures have to be inlined because of performance reasons

inline void SetBit(UINT32* stream, UINT32 pos) {
        stream[pos >> WordWidthLog] |= (1 << (pos%WordWidth));
}

inline void ClearBit(UINT32* stream, UINT32 pos) {
        stream[pos >> WordWidthLog] &= ~(1 << (pos%WordWidth)); 
}

inline bool GetBit(UINT32* stream, UINT32 pos)  {
        return (stream[pos >> WordWidthLog] & (1 << (pos%WordWidth))) > 0;
 
}

inline bool CompareBitBlock(UINT32* stream, UINT32 pos, UINT32 k, UINT32 val) {
        const UINT32 iLoInt = pos >> WordWidthLog;
        const UINT32 iHiInt = (pos + k - 1) >> WordWidthLog;
        ASSERT(iLoInt <= iHiInt);
        const UINT32 mask = (Filled >> (WordWidth - k));
 
        if (iLoInt == iHiInt) {
                // fits into one integer
                val &= mask;
                val <<= (pos%WordWidth);
                return (stream[iLoInt] & val) == val;
        } else {
                // must be splitted over integer boundary
                UINT64 v1 = MAKEU64(stream[iLoInt], stream[iHiInt]);
                UINT64 v2 = UINT64(val & mask) << (pos%WordWidth);
                return (v1 & v2) == v2;
        }
}

inline void SetValueBlock(UINT32* stream, UINT32 pos, UINT32 val, UINT32 k) {
        const UINT32 offset = pos%WordWidth;
        const UINT32 iLoInt = pos >> WordWidthLog;
        const UINT32 iHiInt = (pos + k - 1) >> WordWidthLog;
        ASSERT(iLoInt <= iHiInt);
        const UINT32 loMask = Filled << offset;
        const UINT32 hiMask = Filled >> (WordWidth - 1 - ((pos + k - 1)%WordWidth));
 
        if (iLoInt == iHiInt) {
                // fits into one integer
                stream[iLoInt] &= ~(loMask & hiMask); // clear bits
                stream[iLoInt] |= val << offset; // write value
        } else {
                // must be splitted over integer boundary
                stream[iLoInt] &= ~loMask; // clear bits
                stream[iLoInt] |= val << offset; // write lower part of value
                stream[iHiInt] &= ~hiMask; // clear bits
                stream[iHiInt] |= val >> (WordWidth - offset); // write higher part of value
        }
}

inline UINT32 GetValueBlock(UINT32* stream, UINT32 pos, UINT32 k) {
        UINT32 count, hiCount;
        const UINT32 iLoInt = pos >> WordWidthLog;                              // integer of first bit
        const UINT32 iHiInt = (pos + k - 1) >> WordWidthLog;            // integer of last bit
        const UINT32 loMask = Filled << (pos%WordWidth);
        const UINT32 hiMask = Filled >> (WordWidth - 1 - ((pos + k - 1)%WordWidth));
        
        if (iLoInt == iHiInt) {
                // inside integer boundary
                count = stream[iLoInt] & (loMask & hiMask);
                count >>= pos%WordWidth;
        } else {
                // overlapping integer boundary
                count = stream[iLoInt] & loMask;
                count >>= pos%WordWidth;
                hiCount = stream[iHiInt] & hiMask;
                hiCount <<= WordWidth - (pos%WordWidth);
                count |= hiCount;
        }
        return count;
}

inline void ClearBitBlock(UINT32* stream, UINT32 pos, UINT32 len) {
        ASSERT(len > 0);
        const UINT32 iFirstInt = pos >> WordWidthLog;
        const UINT32 iLastInt = (pos + len - 1) >> WordWidthLog;
 
        const UINT32 startMask = Filled << (pos%WordWidth);
//      const UINT32 endMask=Filled>>(WordWidth-1-((pos+len-1)%WordWidth));
 
        if (iFirstInt == iLastInt) {
                stream[iFirstInt] &= ~(startMask /*& endMask*/);
        } else {
                stream[iFirstInt] &= ~startMask;
                for (UINT32 i = iFirstInt + 1; i <= iLastInt; i++) { // changed <=
                        stream[i] = 0;
                }
                //stream[iLastInt] &= ~endMask;
        }
}

inline void SetBitBlock(UINT32* stream, UINT32 pos, UINT32 len) {
        ASSERT(len > 0);
 
        const UINT32 iFirstInt = pos >> WordWidthLog;
        const UINT32 iLastInt = (pos + len - 1) >> WordWidthLog;
 
        const UINT32 startMask = Filled << (pos%WordWidth);
//      const UINT32 endMask=Filled>>(WordWidth-1-((pos+len-1)%WordWidth));
 
        if (iFirstInt == iLastInt) {
                stream[iFirstInt] |= (startMask /*& endMask*/);
        } else {
                stream[iFirstInt] |= startMask;
                for (UINT32 i = iFirstInt + 1; i <= iLastInt; i++) { // changed <=
                        stream[i] = Filled;
                }
                //stream[iLastInt] &= ~endMask;
        }
}

inline UINT32 SeekBitRange(UINT32* stream, UINT32 pos, UINT32 len) {
        UINT32 count = 0;
        UINT32 testMask = 1 << (pos%WordWidth);
        UINT32* word = stream + (pos >> WordWidthLog);
 
        while (((*word & testMask) == 0) && (count < len)) {
                count++; 
                testMask <<= 1;
                if (!testMask) {
                        word++; testMask = 1;
 
                        // fast steps if all bits in a word are zero
                        while ((count + WordWidth <= len) && (*word == 0)) {
                                word++; 
                                count += WordWidth;
                        }
                }
        }
 
        return count;
}

inline UINT32 SeekBit1Range(UINT32* stream, UINT32 pos, UINT32 len) {
        UINT32 count = 0;
        UINT32 testMask = 1 << (pos%WordWidth);
        UINT32* word = stream + (pos >> WordWidthLog);
 
        while (((*word & testMask) != 0) && (count < len)) {
                count++; 
                testMask <<= 1;
                if (!testMask) {
                        word++; testMask = 1;
 
                        // fast steps if all bits in a word are one
                        while ((count + WordWidth <= len) && (*word == Filled)) {
                                word++; 
                                count += WordWidth;
                        }
                }
        }
        return count;
}

inline UINT32 AlignWordPos(UINT32 pos) {
//      return ((pos + WordWidth - 1) >> WordWidthLog) << WordWidthLog;
        return DWWIDTHBITS(pos);
}

inline UINT32 NumberOfWords(UINT32 pos) {
        return (pos + WordWidth - 1) >> WordWidthLog;
}
#endif //PGF_BITSTREAM_H