BitStream.h File Reference

#include "PGFtypes.h"

Go to the source code of this file.

Macros
#define	MAKEU64(a, b)
	Make 64 bit unsigned integer from two 32 bit unsigned integers.

Functions
void	SetBit (UINT32 *stream, UINT32 pos)
void	ClearBit (UINT32 *stream, UINT32 pos)
bool	GetBit (UINT32 *stream, UINT32 pos)
bool	CompareBitBlock (UINT32 *stream, UINT32 pos, UINT32 k, UINT32 val)
void	SetValueBlock (UINT32 *stream, UINT32 pos, UINT32 val, UINT32 k)
UINT32	GetValueBlock (UINT32 *stream, UINT32 pos, UINT32 k)
void	ClearBitBlock (UINT32 *stream, UINT32 pos, UINT32 len)
void	SetBitBlock (UINT32 *stream, UINT32 pos, UINT32 len)
UINT32	SeekBitRange (UINT32 *stream, UINT32 pos, UINT32 len)
UINT32	SeekBit1Range (UINT32 *stream, UINT32 pos, UINT32 len)
UINT32	AlignWordPos (UINT32 pos)
UINT32	NumberOfWords (UINT32 pos)

Variables
static const UINT32	Filled = 0xFFFFFFFF

Macro Definition Documentation

MAKEU64

#define MAKEU64	(		a,
			b )

Value:

((UINT64) (((UINT32) (a)) | ((UINT64) ((UINT32) (b))) << 32))

Make 64 bit unsigned integer from two 32 bit unsigned integers.

Definition at line 41 of file BitStream.h.

Function Documentation

AlignWordPos()

UINT32 AlignWordPos ( UINT32 pos )

inline

Compute bit position of the next 32-bit word

Parameters

pos	current bit stream position

Returns

bit position of next 32-bit word

Definition at line 328 of file BitStream.h.

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

ClearBit()

void ClearBit ( UINT32 * stream, UINT32 pos )

inline

Set one bit of a bit stream to 0

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream

Definition at line 70 of file BitStream.h.

                                                 {
        stream[pos >> WordWidthLog] &= ~(1 << (pos%WordWidth)); 
}

ClearBitBlock()

void ClearBitBlock ( UINT32 * stream, UINT32 pos, UINT32 len )

inline

Clear block of size at least len at position pos in stream

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream
len	Number of bits set to 0

Definition at line 169 of file BitStream.h.

                                                                  {
        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;
        }
}

CompareBitBlock()

bool CompareBitBlock ( UINT32 * stream, UINT32 pos, UINT32 k, UINT32 val )

inline

Compare k-bit binary representation of stream at position pos with val

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream
k	Number of bits to compare
val	Value to compare with

Returns

true if equal

Definition at line 91 of file BitStream.h.

                                                                              {
        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;
        }
}

GetBit()

bool GetBit ( UINT32 * stream, UINT32 pos )

inline

Return one bit of a bit stream

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream

Returns

bit at position pos of bit stream stream

Definition at line 79 of file BitStream.h.

                                                {
        return (stream[pos >> WordWidthLog] & (1 << (pos%WordWidth))) > 0;
 
}

GetValueBlock()

UINT32 GetValueBlock ( UINT32 * stream, UINT32 pos, UINT32 k )

inline

Read k-bit number from stream at position pos

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream
k	Number of bits to read: 1 <= k <= 32

Definition at line 142 of file BitStream.h.

                                                                  {
        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;
}

NumberOfWords()

UINT32 NumberOfWords ( UINT32 pos )

inline

Compute number of the 32-bit words

Parameters

pos	Current bit stream position

Returns

Number of 32-bit words

Definition at line 337 of file BitStream.h.

                                        {
        return (pos + WordWidth - 1) >> WordWidthLog;
}

SeekBit1Range()

UINT32 SeekBit1Range ( UINT32 * stream, UINT32 pos, UINT32 len )

inline

Returns the distance to the next 0 in stream at position pos. If no 0 is found within len bits, then len is returned.

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream
len	size of search area (in bits) return The distance to the next 0 in stream at position pos

Definition at line 249 of file BitStream.h.

                                                                    {
        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;
}

SeekBitRange()

UINT32 SeekBitRange ( UINT32 * stream, UINT32 pos, UINT32 len )

inline

Returns the distance to the next 1 in stream at position pos. If no 1 is found within len bits, then len is returned.

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream
len	size of search area (in bits) return The distance to the next 1 in stream at position pos

Definition at line 220 of file BitStream.h.

                                                                   {
        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;
}

SetBit()

void SetBit ( UINT32 * stream, UINT32 pos )

inline

Set one bit of a bit stream to 1

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream

Definition at line 62 of file BitStream.h.

                                               {
        stream[pos >> WordWidthLog] |= (1 << (pos%WordWidth));
}

SetBitBlock()

void SetBitBlock ( UINT32 * stream, UINT32 pos, UINT32 len )

inline

Set block of size at least len at position pos in stream

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream
len	Number of bits set to 1

Definition at line 193 of file BitStream.h.

                                                                {
        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;
        }
}

SetValueBlock()

void SetValueBlock ( UINT32 * stream, UINT32 pos, UINT32 val, UINT32 k )

inline

Store k-bit binary representation of val in stream at position pos

Parameters

stream	A bit stream stored in array of unsigned integers
pos	A valid zero-based position in the bit stream
val	Value to store in stream at position pos
k	Number of bits of integer representation of val

Definition at line 116 of file BitStream.h.

                                                                            {
        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
        }
}

Variable Documentation

Filled

const UINT32 Filled = 0xFFFFFFFF

static

Definition at line 38 of file BitStream.h.