lcwpipe.cpp

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/*
**  Command & Conquer Generals Zero Hour(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/>.
*/
 
/*********************************************************************************************** 
 ***              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                                            * 
 *                                                                                             * 
 *                     $Archive:: /Commando/Library/LCWPIPE.CPP                               $* 
 *                                                                                             * 
 *                      $Author:: Greg_h                                                      $*
 *                                                                                             * 
 *                     $Modtime:: 7/22/97 11:37a                                              $*
 *                                                                                             * 
 *                    $Revision:: 1                                                           $*
 *                                                                                             *
 *---------------------------------------------------------------------------------------------* 
 * Functions:                                                                                  * 
 *   LCWPipe::Flush -- Flushes any partially accumulated block.                                *
 *   LCWPipe::LCWPipe -- Constructor for the LCW processor pipe.                               *
 *   LCWPipe::Put -- Send some data through the LCW processor pipe.                            *
 *   LCWPipe::~LCWPipe -- Deconstructor for the LCW pipe object.                               *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
 
#include    "always.h"
#include    "lcw.h"
#include    "lcwpipe.h"
#include    <assert.h>
#include    <string.h>
 
 
/***********************************************************************************************
 * LCWPipe::LCWPipe -- Constructor for the LCW processor pipe.                                 *
 *                                                                                             *
 *    This will initialize the LCWPipe 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.                                                                 *
 *=============================================================================================*/
LCWPipe::LCWPipe(CompControl control, int blocksize) :
        Control(control),
        Counter(0),
        Buffer(NULL),
        Buffer2(NULL),
        BlockSize(blocksize)
{
    SafetyMargin = BlockSize/128+1;
    Buffer = new char[BlockSize+SafetyMargin];
    Buffer2 = new char[BlockSize+SafetyMargin];
    BlockHeader.CompCount = 0xFFFF;
}
 
 
/***********************************************************************************************
 * LCWPipe::~LCWPipe -- Deconstructor for the LCW pipe object.                                 *
 *                                                                                             *
 *    This will free any buffers it may have allocated.                                        *
 *                                                                                             *
 * INPUT:   none                                                                               *
 *                                                                                             *
 * OUTPUT:  none                                                                               *
 *                                                                                             *
 * WARNINGS:   none                                                                            *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   07/04/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
LCWPipe::~LCWPipe(void)
{
    delete [] Buffer;
    Buffer = NULL;
 
    delete [] Buffer2;
    Buffer2 = NULL;
}
 
 
/***********************************************************************************************
 * LCWPipe::Put -- Send some data through the LCW 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 LCW 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 LCWPipe::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 = ((unsigned)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) {
                    LCW_Uncomp(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 = LCW_Comp(Buffer, Buffer2, BlockSize);
 
                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 = LCW_Comp(source, Buffer2, BlockSize);
 
            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);
}
 
 
/***********************************************************************************************
 * LCWPipe::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 LCWPipe::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 LCW 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 = LCW_Comp(Buffer, Buffer2, Counter);
 
            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);
}