RedAlert/CODE/LZWPIPE.CPP

/*
**	Command & Conquer Red Alert(tm)
**	Copyright 2025 Electronic Arts Inc.
**
**	This program is free software: you can redistribute it and/or modify
**	it under the terms of the GNU General Public License as published by
**	the Free Software Foundation, either version 3 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, see <http://www.gnu.org/licenses/>.
*/

/* $Header: /CounterStrike/LZWPIPE.CPP 1     3/03/97 10:25a Joe_bostic $ */
/***********************************************************************************************
 ***              C O N F I D E N T I A L  ---  W E S T W O O D  S T U D I O S               ***
 ***********************************************************************************************
 *                                                                                             *
 *                 Project Name : Command & Conquer                                            *
 *                                                                                             *
 *                    File Name : LZWPIPE.CPP                                                  *
 *                                                                                             *
 *                   Programmer : Joe L. Bostic                                                *
 *                                                                                             *
 *                   Start Date : 06/30/96                                                     *
 *                                                                                             *
 *                  Last Update : July 4, 1996 [JLB]                                           *
 *                                                                                             *
 *---------------------------------------------------------------------------------------------*
 * Functions:                                                                                  *
 *   LZWPipe::Flush -- Flushes any partially accumulated block.                                *
 *   LZWPipe::LZWPipe -- Constructor for the LZW processor pipe.                               *
 *   LZWPipe::Put -- Send some data through the LZW processor pipe.                            *
 *   LZWPipe::~LZWPipe -- Deconstructor for the LZW pipe object.                               *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */


#include	"lzwpipe.h"
#include	"lzw.h"
#include	"buff.h"
#include	<string.h>
#include	<assert.h>


/***********************************************************************************************
 * LZWPipe::LZWPipe -- Constructor for the LZW processor pipe.                                 *
 *                                                                                             *
 *    This will initialize the LZWPipe object so that it is prepared for compression or        *
 *    decompression as indicated.                                                              *
 *                                                                                             *
 * INPUT:   decrypt  -- Should decompression be performed?                                     *
 *                                                                                             *
 *          blocksize-- The size of the data blocks to process.                                *
 *                                                                                             *
 * OUTPUT:  none                                                                               *
 *                                                                                             *
 * WARNINGS:   none                                                                            *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   07/04/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
LZWPipe::LZWPipe(CompControl control, int blocksize) :
		Control(control),
		Counter(0),
		Buffer(NULL),
		Buffer2(NULL),
		BlockSize(blocksize)
{
	SafetyMargin = BlockSize;
//	SafetyMargin = BlockSize/128+1;
	Buffer = new char[BlockSize+SafetyMargin];
	Buffer2 = new char[BlockSize+SafetyMargin];
	BlockHeader.CompCount = 0xFFFF;
}


/***********************************************************************************************
 * LZWPipe::~LZWPipe -- Deconstructor for the LZW pipe object.                                 *
 *                                                                                             *
 *    This will free any buffers it may have allocated.                                        *
 *                                                                                             *
 * INPUT:   none                                                                               *
 *                                                                                             *
 * OUTPUT:  none                                                                               *
 *                                                                                             *
 * WARNINGS:   none                                                                            *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   07/04/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
LZWPipe::~LZWPipe(void)
{
	delete [] Buffer;
	Buffer = NULL;

	delete [] Buffer2;
	Buffer2 = NULL;
}


/***********************************************************************************************
 * LZWPipe::Put -- Send some data through the LZW processor pipe.                              *
 *                                                                                             *
 *    This routine will take the data requested and process it (decompression or compression). *
 *    It does this by accumulating the necessary bytes to make a whole block. Then the block   *
 *    is processed and the entire contents are flushed to the next pipe segment in the chain.  *
 *                                                                                             *
 * INPUT:   source   -- Pointer to the data to be fed to this LZW processor.                   *
 *                                                                                             *
 *          length   -- The number of bytes received.                                          *
 *                                                                                             *
 * OUTPUT:  Returns with the actual number of bytes output at the far distant final link in    *
 *          the pipe chain.                                                                    *
 *                                                                                             *
 * WARNINGS:   The compression process may be slow as well as consuming two buffers.           *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   07/04/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
int LZWPipe::Put(void const * source, int slen)
{
	if (source == NULL || slen < 1) {
		return(Pipe::Put(source, slen));
	}

	assert(Buffer != NULL);

	int total = 0;

	/*
	**	Copy as much as can fit into the buffer from the source data supplied.
	*/
	if (Control ==  DECOMPRESS) {

		while (slen > 0) {

			/*
			**	First check to see if we are in the block header accumulation phase.
			**	When a whole block header has been accumulated, only then will the regular
			**	data processing begin for the block.
			*/
			if (BlockHeader.CompCount == 0xFFFF) {
				int len = (slen < (sizeof(BlockHeader)-Counter)) ? slen : (sizeof(BlockHeader)-Counter);
				memmove(&Buffer[Counter], source, len);
				source = ((char *)source) + len;
				slen -= len;
				Counter += len;

				/*
				**	A whole block header has been accumulated. Store it for safekeeping.
				*/
				if (Counter == sizeof(BlockHeader)) {
					memmove(&BlockHeader, Buffer, sizeof(BlockHeader));
					Counter = 0;
				}
			}

			/*
			**	Fill the buffer with compressed data until there is enough to make a whole
			**	data block.
			*/
			if (slen > 0) {
				int len = (slen < (BlockHeader.CompCount-Counter)) ? slen : (BlockHeader.CompCount-Counter);

				memmove(&Buffer[Counter], source, len);
				slen -= len;
				source = ((char *)source) + len;
				Counter += len;

				/*
				**	If an entire block has been accumulated, then uncompress it and feed it
				**	through the pipe.
				*/
				if (Counter == BlockHeader.CompCount) {
					LZW_Uncompress(Buffer, Buffer2);
					total += Pipe::Put(Buffer2, BlockHeader.UncompCount);
					Counter = 0;
					BlockHeader.CompCount = 0xFFFF;
				}
			}
		}

	} else {

		/*
		**	If the buffer already contains some data, then any new data must be stored
		**	into the staging buffer until a full set has been accumulated.
		*/
		if (Counter > 0) {
			int tocopy = (slen < (BlockSize-Counter)) ? slen : (BlockSize-Counter);
			memmove(&Buffer[Counter], source, tocopy);
			source = ((char *)source) + tocopy;
			slen -= tocopy;
			Counter += tocopy;

			if (Counter == BlockSize) {
				int len = LZW_Compress(::Buffer(Buffer, BlockSize), Buffer2);

				BlockHeader.CompCount = (unsigned short)len;
				BlockHeader.UncompCount = (unsigned short)BlockSize;
				total += Pipe::Put(&BlockHeader, sizeof(BlockHeader));
				total += Pipe::Put(Buffer2, len);
				Counter = 0;
			}
		}

		/*
		**	Process the source data in whole block chunks until there is insufficient
		**	source data left for a whole data block.
		*/
		while (slen >= BlockSize) {
			int len = LZW_Compress(::Buffer((void*)source, BlockSize), Buffer2);

			source = ((char *)source) + BlockSize;
			slen -= BlockSize;

			BlockHeader.CompCount = (unsigned short)len;
			BlockHeader.UncompCount = (unsigned short)BlockSize;
			total += Pipe::Put(&BlockHeader, sizeof(BlockHeader));
			total += Pipe::Put(Buffer2, len);
		}

		/*
		**	If there is any remaining data, then it is stored into the buffer
		**	until a full data block has been accumulated.
		*/
		if (slen > 0) {
			memmove(Buffer, source, slen);
			Counter = slen;
		}
	}

	return(total);
}


/***********************************************************************************************
 * LZWPipe::Flush -- Flushes any partially accumulated block.                                  *
 *                                                                                             *
 *    This routine is called when any buffered data must be flushed out the pipe. For the      *
 *    compression process, this will generate the sub-sized compressed block. For              *
 *    decompression, this routine should not have any data in the buffer. In such a case, it   *
 *    means that the data source was prematurely truncated. In such a case, just dump the      *
 *    accumulated data through the pipe.                                                       *
 *                                                                                             *
 * INPUT:   none                                                                               *
 *                                                                                             *
 * OUTPUT:  Returns with the actual number of data bytes output to the distant final link in   *
 *          the pipe chain.                                                                    *
 *                                                                                             *
 * WARNINGS:   none                                                                            *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   07/04/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
int LZWPipe::Flush(void)
{
	assert(Buffer != NULL);

	int total = 0;

	/*
	**	If there is accumulated data, then it must processed.
	*/
	if (Counter > 0) {
		if (Control == DECOMPRESS) {

			/*
			**	If the accumulated data is insufficient to make a block header, then
			**	this means the data has been truncated. Just dump the data through
			**	as if were already decompressed.
			*/
			if (BlockHeader.CompCount == 0xFFFF) {
				total += Pipe::Put(Buffer, Counter);
				Counter = 0;
			}

			/*
			**	There appears to be a partial block accumulated in the buffer. It would
			**	be disastrous to try to decompress the data since there wouldn't be
			**	the special end of data code that LZW decompression needs. In this
			**	case, dump the data out as if it were already decompressed.
			*/
			if (Counter > 0) {
				total += Pipe::Put(&BlockHeader, sizeof(BlockHeader));
				total += Pipe::Put(Buffer, Counter);
				Counter = 0;
				BlockHeader.CompCount = 0xFFFF;
			}

		} else {

			/*
			**	A partial block in the compression process is a normal occurrence. Just
			**	compress the partial block and output normally.
			*/
			int len = LZW_Compress(::Buffer(Buffer, Counter), Buffer2);

			BlockHeader.CompCount = (unsigned short)len;
			BlockHeader.UncompCount = (unsigned short)Counter;
			total += Pipe::Put(&BlockHeader, sizeof(BlockHeader));
			total += Pipe::Put(Buffer2, len);
			Counter = 0;
		}
	}

	total += Pipe::Flush();
	return(total);
}