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12 Feb 2007

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BitField Class Reference

<class description="" goes="" here=""> <short description=""> More...

#include <BitField.hpp>

List of all members.

Public Member Functions
	BitField (char *data, u32 size)
	BitField (u32 size, bool initValue)
void	setBit (u32 pos)
	sets the bit at position
void	clearBit (u32 pos)
	sets the bit at position
bool	getBit (u32 pos) const
	gets the bit at position
void	invert ()
	inverts all 1 to 0 and all 0 to 1
u32	getBitRange (u32 startPos, int *nrBits, bool littleEndian=true)
	returns
bool	writeBitRange (u32 startPos, int nrBits, u32 value, u32 startBit, bool littleEndian=true)
bool	isAllSet () const
	returns true if the bitfield consists completely of 1s
bool	isAllCleared () const
	returns true if the bitfield consists completely of 0s
float	getPercentageSetBits () const
	returns the percentage of 1s inthe bitfield.
BitField *	createWithNewSize (u32 size, bool initValueForMissing)
	creates a new BitField with new size
u32	getSize () const
const char *	toBinaryString (u32 *sizeInU32) const
	simply returns a pointer to the internal bitfield.
char *	toAsciiString () const
	converts the bitfield into a human viewer friendly 01 ASCII presentation.
char *	toHexString () const
	converts the bitfield into a hex representation of the form size_0123456789ABCDEF...
Static Public Member Functions
BitField *	fromAsciiString (const char *str)
	creates a Bitfield from a string of chars '0' and '1'.
BitField *	fromBinaryString (const char *bin, u32 numBits)
	creates a Bitfield from a binary data pointer.
BitField *	fromBinaryString (char *bin, u32 numBits)
	same as above but faster because only a shallow-copy is performed
BitField *	fromHexString (const char *bin)
	creates a bitfield from its hex presentation
void	doTest ()
	automatic testing of BitField functionality, throws assertion at any error found

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Detailed Description

<class description="" goes="" here=""> <short description="">

Author:

Michael Kropfberger and Peter Schojer

Version:

Id

BitField.hpp,v 1.4 2004/05/19 22:19:01 mkropfbe Exp

Definition at line 62 of file BitField.hpp.

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Member Function Documentation

void BitField::clearBit (  u32  pos  )

sets the bit at position Parameters: pos  to 0. if pos points to an invalid bit, the clear is ignored Definition at line 75 of file BitField.cpp. Referenced by createWithNewSize(), fromAsciiString(), fromHexString(), and invert(). { if(pos>=maxSize) return; //dprintf_full("BitField::clearBit(u32 %u) first u32 is %u\n",pos,bits[0]); u32 posInArray=pos/(sizeof(u32)*8); u32 bitInPos=pos%(sizeof(u32)*8); bits[posInArray]&=(((u32)0xffffffff)-(1<<bitInPos)); };

BitField * BitField::createWithNewSize (  u32  size, bool  initValueForMissing )

creates a new BitField with new size Parameters: size.  If the new size is smaller than the current size, the old values are copied from pos 0 to newSize. if the new size is the same than the current size, this method has clone functionality. if the new size is larger than the current size, the current data is cloned and the values afterwards are set to initValueForMissing  Definition at line 126 of file BitField.cpp. References bits, clearBit(), getBit(), and setBit(). Referenced by ESInfo::setVOPTimeIncrement(). { BitField* b=new BitField(size,initValueForMissing); // copy full bytes with normal memcopy u32 posInArray=size/(sizeof(u32)*8); if(size>maxSize) //prevent buffer overflow posInArray=maxSize/(sizeof(u32)*8); memcpy(b->bits,bits,posInArray*sizeof(u32)); // copy the remaining bits (up to 31) manually u32 startPosRemaining=posInArray*(sizeof(u32)*8); u32 endPos=MIN(size,maxSize); for(u32 i=startPosRemaining;i<endPos;i++) { if(getBit(i)) b->setBit(i); else b->clearBit(i); } return b; };

BitField * BitField::fromAsciiString (  const char *  str  )  [static]

creates a Bitfield from a string of chars '0' and '1'. Time expensive but endian save! Definition at line 224 of file BitField.cpp. References clearBit(). Referenced by doTest(). { if(str==NULL) return NULL; u32 sizeStr=strlen(str); BitField* b=new BitField(sizeStr,true); // only check for 0 and just hope that the string is valid // init to 1 because hopefully we will have more 1 than 0 // in the string for(u32 i=0;i<sizeStr;i++) { if(str[i]=='0') b->clearBit(i); } return b; };

BitField * BitField::fromBinaryString (  const char *  bin, u32  numBits )  [static]

creates a Bitfield from a binary data pointer. fast but not endian save Definition at line 243 of file BitField.cpp. References bits. { BitField* b=new BitField(numBits,false); u32 bytes=(numBits+sizeof(char)-1)/sizeof(char); memcpy(b->bits,bin,bytes); return b; };

bool BitField::getBit (  u32  pos  )  const

gets the bit at position Parameters: pos.  if pos points to an invalid bit, always false is returned Definition at line 95 of file BitField.cpp. Referenced by createWithNewSize(), doTest(), getBitRange(), FilteredIO::getFrame(), getPercentageSetBits(), invert(), isAllCleared(), isAllSet(), toAsciiString(), toHexString(), and FilteredIO::writeFrame(). { if(pos>=maxSize) return false; u32 posInArray=pos/(sizeof(u32)*8); u32 bitInPos=pos%(sizeof(u32)*8); return bits[posInArray]&(1<<bitInPos); };

u32 BitField::getBitRange (  u32  startPos, int *  nrBits, bool  littleEndian = true )

returns Parameters: nrBits  from the bitfield, starting with bitPos startPos.  if nrBits is an invalid value (0 or greater 32) or if the specified bit range exceeds the size of the bitfield, nrBits  is set to -1. littleEndian  specifies endianness. When set to true the decimal value for the requested bitrange is calculated as if the first bit has the lowest value. e.g.: Bit 0 1000 Bit 3 -> littleEndian=true --> 1 littleEndian=false --> 8 If everything went fine nrBits returns the number of bits used to create return,otherwise  return  is 0 and nrBits  is -1 Definition at line 346 of file BitField.cpp. References getBit(). Referenced by doTest(). { assert(nrBits); if( (*nrBits)==0 || (*nrBits)>32 || startPos+(*nrBits)>maxSize) { (*nrBits)=-1; return 0; } // everything is valid u32 result=0; u32 shamt=0; //shift amount u32 i=0; if(!littleEndian) { shamt=(*nrBits)-1; } for (i=startPos;i<startPos+(*nrBits);i++) { result+=(getBit(i)?1:0)<<shamt; if(littleEndian) shamt++; else shamt--; } return result; };

float BitField::getPercentageSetBits (   )  const

returns the percentage of 1s inthe bitfield. Expensive!!! Definition at line 209 of file BitField.cpp. References getBit(). Referenced by doTest(), and ProxySession::tearDown(). { float res=0; int count=0; for(u32 i=0;i<maxSize;i++) { if(getBit(i)) count++; } if(count>0) // thus maxSize > 0 res= (float)((double)count)/((double)maxSize); return res; };

void BitField::setBit (  u32  pos  )

sets the bit at position Parameters: pos  to 1. if pos points to an invalid bit, the set is ignored Definition at line 85 of file BitField.cpp. Referenced by createWithNewSize(), doTest(), invert(), RawStreamIO::writeFrame(), MPGStreamIO::writeFrame(), and BufferedIO::writeFrame(). { if(pos>=maxSize) return; //dprintf_full("BitField::setBit(u32 %u) first u32 is %u\n",pos,bits[0]); u32 posInArray=pos/(sizeof(u32)*8); u32 bitInPos=pos%(sizeof(u32)*8); bits[posInArray]|=(1<<bitInPos); };

char * BitField::toAsciiString (   )  const

converts the bitfield into a human viewer friendly 01 ASCII presentation. Time expensive but endian save! Definition at line 160 of file BitField.cpp. References getBit(). Referenced by doTest(). { char* temp=new char[maxSize+1]; for(u32 i=0;i<maxSize;i++) temp[i]=( getBit(i) ? '1' : '0'); temp[maxSize]='\0'; return temp; };

const char * BitField::toBinaryString (  u32 *  sizeInU32  )  const

simply returns a pointer to the internal bitfield. returns the size which is multiple of sizeof(u32) Definition at line 152 of file BitField.cpp. { *sizeInU32=(maxSize+(sizeof(u32)*8-1))/(sizeof(u32)*8); return (const char*)bits; };

char * BitField::toHexString (   )  const

converts the bitfield into a hex representation of the form size_0123456789ABCDEF... Example: A Bitfield with the size 9, data:(bit 0) 000111110 (bit 8) is in hex: 00000009_8F0Definition at line 261 of file BitField.cpp. References getBit(). Referenced by doTest(), and FilteredIO::setBitField(). { // one char represents 4 bits 0111 -> 7 int size=(maxSize+3)/4; // add 9 Byte header (32bit size in Hex + _) size+=9; char* result=new char[size+1]; // write header sprintf(result,"%8X_",maxSize); int cnt=0; for(u32 i=0;i<maxSize;i+=4) { cnt=(getBit(i) ? 1 : 0); cnt+=(getBit(i+1) ? 1 : 0)<<1; cnt+=(getBit(i+2) ? 1 : 0)<<2; cnt+=(getBit(i+3) ? 1 : 0)<<3; if(cnt>9) { cnt-=10; cnt+='A'; } else cnt+='0'; result[9+i/4]=cnt; } result[size]='\0'; return result; };

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The documentation for this class was generated from the following files:

• BitField.hpp
• BitField.cpp

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