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