Work/gif/LZW.CPP

#include <gif/lzw.hpp>

USHORT LZWDecompression::mStartTable[LZWDecompression::STARTTABLESIZE]=
 {0x00,0x04,0x02,0x01,0x00};

USHORT LZWDecompression::mIncTable[LZWDecompression::INCTABLESIZE]=
 {0x08,0x08,0x04,0x02,0x00};

USHORT LZWDecompression::mcMask[LZWDecompression::CMASKSIZE]=
 {0x00,0x01,0x03,0x07,0x0F,0x1F,0x3F,0x7F,0xFF};

CHAR LZWDecompression::errorMessage[]="Error reading data.";

LZWDecompression::LZWDecompression(void)
: mhGlobalctFirst(0), mhGlobalctLast(0), mhGlobalctLink(0),
	mhGlobalOutRow(0), mhGlobalStack(0), mlpctFirst(0), mlpctLast(0),
	mlpctLink(0), mlpOutRow(0), mlpStack(0), mNextCode(0), mNextLimit(0),
	mBufferCount(0), mRemct(0), mRem(0), mPass(0), mxLocation(0),
	myLocation(0), mRowCount(0), mIsConstructed(FALSE), mReqct(0), mCode(0)
{
  initialize();
}

LZWDecompression::~LZWDecompression()
{
	if(!mIsConstructed)return;
	cleanup();
}

BOOL LZWDecompression::initialize(void)
{
  cleanup();
	mhGlobalctFirst=::GlobalAlloc(GMEM_FIXED,CTSIZE);
	mhGlobalctLast=::GlobalAlloc(GMEM_FIXED,CTSIZE);
	mhGlobalctLink=::GlobalAlloc(GMEM_FIXED,CTSIZE*sizeof(USHORT));
	mhGlobalOutRow=::GlobalAlloc(GMEM_FIXED,OUTROWSIZE);
	mhGlobalStack=::GlobalAlloc(GMEM_FIXED,STACKSIZE);
	if(!mhGlobalctFirst||!mhGlobalctLast||!mhGlobalctLink||!mhGlobalOutRow||!mhGlobalStack)return FALSE;
	mlpctFirst=(CHAR FAR *)::GlobalLock(mhGlobalctFirst);
	mlpctLast=(CHAR FAR *)::GlobalLock(mhGlobalctLast);
	mlpctLink=(SHORT FAR *)::GlobalLock(mhGlobalctLink);
	mlpOutRow=(UCHAR FAR *)::GlobalLock(mhGlobalOutRow);
	mlpStack=(UCHAR FAR *)::GlobalLock(mhGlobalStack);
	::memset(mlpctFirst,0,CTSIZE);
	::memset(mlpctLast,0,CTSIZE);
	::memset(mlpctLink,0,CTSIZE*sizeof(USHORT));
	::memset(mlpOutRow,0,OUTROWSIZE);
	::memset(mlpStack,0,STACKSIZE);
	mIsConstructed=TRUE;
  return TRUE;
}

BOOL LZWDecompression::unpackData(USHORT imageWide,USHORT imageDeep,USHORT isInterlaced,USHORT bitsPerPixel)
{
	USHORT clearCode;
	USHORT pixelSize;
	USHORT endOfInput;
  CHAR firstCode;

  initialize();
  firstCode=currentChar();  
	mImageWide=imageWide;
	mImageDeep=imageDeep;
	mIsInterlaced=isInterlaced;
	pixelSize=bitsPerPixel;
	clearCode=(1<<currentChar());
	endOfInput=(1<<currentChar())+1;
	mReqct=currentChar()+1;
	initializeTable(clearCode);
	mOldCode=0xFFFF;
	mPass=0x0000;
	mRowCount=mImageWide;
	mxLocation=0x0000;
	myLocation=0x0000;
	while(TRUE)
	{
		mCode=getCode(mReqct);
		if(mCode==clearCode)
		{
			initializeTable(clearCode);
			mReqct=firstCode+1;
			mOldCode=0xFFFF;
		}
		else
		{
		  if(mCode==endOfInput)
		  {
		    flush();
		    break;
		  }
		  else
		  {
				if(0xFFFE!=(USHORT)*(mlpctLink+mCode))
				{
					if(0xFFFF!=mOldCode)if(!insertCode(mCode))break;
				}
				else if(!insertCode(mOldCode))break;
			}
		  putx(mCode,pixelSize);
		  mOldCode=mCode;
		}
	}
	return TRUE;
}

void LZWDecompression::putx(SHORT code,SHORT pixelSize)
{
	SHORT tempCode;
	UCHAR FAR *lpStack=mlpStack;
	int i=0;

	while(TRUE)
	{
		*lpStack=*(mlpctLast+code);
		lpStack++;
		i++;
		code=*(mlpctLink+code);
		if(-1>=code)break;
	}
	if(1==pixelSize)
	{
		while(i>0)
		{
			lpStack--;
			tempCode=(*lpStack)&0x0001;
			doPixel(tempCode);
			tempCode=(*lpStack)&0x00FF;
			tempCode>>=1;
			doPixel(tempCode);
			i--;
		}
	}
	else
	{
		while(i>0)
		{
			lpStack--;
			tempCode=(*lpStack)&0x00FF;
			doPixel(tempCode);
      i--;
    }
  }
}

void LZWDecompression::doPixel(CHAR tempCode)
{
	*(mlpOutRow+mxLocation)=tempCode;
	mxLocation++;
	mRowCount--;
	if(0!=mRowCount)return;
	showHandler(mlpOutRow,myLocation);
	mxLocation=0;
	mRowCount=mImageWide;
	if(!mIsInterlaced)
	{
		myLocation++;
		if(myLocation>=mImageDeep)myLocation=0;
	}
	else
	{
		myLocation+=mIncTable[mPass];
		if(myLocation<mImageDeep)return;
		myLocation=mStartTable[++mPass];
	}
	return;
}

void LZWDecompression::initializeTable(SHORT clearCode)
{
	mNextCode=clearCode+2;
	mNextLimit=(clearCode<<1);
	for(int i=0;i<CTSIZE;i++)
	{
		if(i<clearCode)
		{
			*(mlpctFirst+i)=i;
			*(mlpctLast+i)=i;
      *(mlpctLink+i)=-1;
		}
		else *(mlpctLink+i)=-2;
  }
}

UCHAR LZWDecompression::getGB(void)
{
	if(0!=mBufferCount)
	{
		if(!getChar())
		{
			errorHandler(errorMessage);
			return currentChar();
		}
		mBufferCount--;
		return currentChar();
	}
	if(!getChar())
	{
		errorHandler(errorMessage);
		return currentChar();
	}
	mBufferCount=currentChar();
	if(!mBufferCount)errorHandler(errorMessage);
	if(!getChar())return currentChar();
	mBufferCount--;
	return currentChar();
}

USHORT LZWDecompression::getBCode(USHORT code)
{
	USHORT tempCode;
	USHORT temp;

	if(0==mRemct)
	{
		mRem=getGB();
		mRemct=8;
	}
	if(mRemct<code)
	{
		tempCode=getGB();
		tempCode<<=mRemct;
		mRem|=tempCode;
    mRemct+=8;
	}
	temp=mcMask[code];
	temp&=0x00FF;
	tempCode=mRem;
	tempCode&=temp;
	mRemct-=code;
	mRem>>=(code&0x00FF);
	return tempCode;
}

USHORT LZWDecompression::getCode(USHORT reqct)
{
	USHORT tempCode1;
	USHORT tempCode2;

	if(reqct<=8)return getBCode(reqct);
	tempCode1=getBCode(8);
	tempCode2=getBCode(reqct-8);
	tempCode2<<=8;
	tempCode2|=tempCode1;
	return tempCode2;
}

WORD LZWDecompression::insertCode(SHORT code)
{
  if(mNextCode>=CTSIZE)return FALSE;
  *(mlpctLink+mNextCode)=mOldCode;
  *(mlpctLast+mNextCode)=*(mlpctFirst+code);
  *(mlpctFirst+mNextCode)=*(mlpctFirst+mOldCode);
  mNextCode++;
  if(mNextCode!=mNextLimit)return TRUE;
  if(mReqct>=12)return TRUE;
  mReqct++;
  mNextLimit<<=1;
  return TRUE;
}

void LZWDecompression::flush(void)
{
	while(TRUE)
	{
		if(0==mBufferCount)
		{
		  if(!getChar())return;
			mBufferCount=currentChar();
			if(0==mBufferCount)return;
		}
		else
    {
			if(!getChar())return;
			mBufferCount--;
    }
	}
}

void LZWDecompression::cleanup(void)
{
	if(mhGlobalctFirst)
	{
		::GlobalUnlock(mhGlobalctFirst);
    ::GlobalFree(mhGlobalctFirst);
		mhGlobalctFirst=0;
	}
	if(mhGlobalctLast)
	{
		::GlobalUnlock(mhGlobalctLast);
		::GlobalFree(mhGlobalctLast);
		mhGlobalctLast=0;
	}
	if(mhGlobalctLink)
	{
		::GlobalUnlock(mhGlobalctLink);
		::GlobalFree(mhGlobalctLink);
		mhGlobalctLink=0;
	}
	if(mhGlobalOutRow)
	{
		::GlobalUnlock(mhGlobalOutRow);
		::GlobalFree(mhGlobalOutRow);
		mhGlobalOutRow=0;
	}
	if(mhGlobalStack)
	{
		::GlobalUnlock(mhGlobalStack);
		::GlobalFree(mhGlobalStack);
		mhGlobalStack=0;
  }
	mIsConstructed=FALSE;
  mlpctFirst=0;
	mlpctLast=0;
	mlpctLink=0;
	mlpOutRow=0;
	mlpStack=0;
	mNextCode=0;
	mNextLimit=0;
	mBufferCount=0;
	mRemct=0;
	mRem=0;
	mPass=0;
	mxLocation=0;
	myLocation=0;
	mRowCount=0;
	mReqct=0;
	mCode=0;
}

// VIRTUALS

void LZWDecompression::showHandler(UCHAR FAR * /*lpOutRow*/,USHORT /*yLocation*/)
{
}

void LZWDecompression::errorHandler(CHAR * /*errorMessage*/)
{
}