lzostraw.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/LZOSTRAW.CPP                              $* 
 *                                                                                             * 
 *                      $Author:: Greg_h                                                      $*
 *                                                                                             * 
 *                     $Modtime:: 7/22/97 11:37a                                              $*
 *                                                                                             * 
 *                    $Revision:: 1                                                           $*
 *                                                                                             *
 *---------------------------------------------------------------------------------------------* 
 * Functions:                                                                                  * 
 *   LZOStraw::Get -- Fetch data through the LZO processor.                                    *
 *   LZOStraw::LZOStraw -- Constructor for LZO straw object.                                   *
 *   LZOStraw::~LZOStraw -- Destructor for the LZO straw.                                      *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
#include    "always.h"
#include    "lzo.h"
#include    "lzostraw.h"
#include    <assert.h>
#include    <string.h>
 
 
/***********************************************************************************************
 * LZOStraw::LZOStraw -- Constructor for LZO straw object.                                     *
 *                                                                                             *
 *    This will initialize the LZO straw object. Whether the object is to compress or          *
 *    decompress and the block size to use is specified. The data is compressed in blocks      *
 *    that are sized to be quick to compress and yet still yield good compression ratios.      *
 *                                                                                             *
 * INPUT:   decrypt  -- Should the data be decompressed?                                       *
 *                                                                                             *
 *          blocksize-- The size of the blocks to process.                                     *
 *                                                                                             *
 * OUTPUT:  none                                                                               *
 *                                                                                             *
 * WARNINGS:   It takes two buffers of the blocksize specified if compression is to be         *
 *             performed.                                                                      *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   07/04/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
LZOStraw::LZOStraw(CompControl control, int blocksize) :
        Control(control),
        Counter(0),
        Buffer(NULL),
        Buffer2(NULL),
        BlockSize(blocksize)
{
    SafetyMargin = BlockSize;
    Buffer = new char[BlockSize+SafetyMargin];
    if (control == COMPRESS) {
        Buffer2 = new char[BlockSize+SafetyMargin];
    }
}
 
 
/***********************************************************************************************
 * LZOStraw::~LZOStraw -- Destructor for the LZO straw.                                        *
 *                                                                                             *
 *    The destructor will free up the allocated buffers that it allocated in the constructor.  *
 *                                                                                             *
 * INPUT:   none                                                                               *
 *                                                                                             *
 * OUTPUT:  none                                                                               *
 *                                                                                             *
 * WARNINGS:   none                                                                            *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   07/04/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
LZOStraw::~LZOStraw(void)
{
    delete [] Buffer;
    Buffer = NULL;
 
    delete [] Buffer2;
    Buffer2 = NULL;
}
 
 
/***********************************************************************************************
 * LZOStraw::Get -- Fetch data through the LZO processor.                                      *
 *                                                                                             *
 *    This routine will fetch the data bytes specified. It does this by first accumulating     *
 *    a full block of data and then compressing or decompressing it as indicated. Subsequent   *
 *    requests for data will draw from this buffer of processed data until it is exhausted     *
 *    and another block must be fetched.                                                       *
 *                                                                                             *
 * INPUT:   destbuf  -- Pointer to the buffer to hold the data requested.                      *
 *                                                                                             *
 *          length   -- The number of data bytes requested.                                    *
 *                                                                                             *
 * OUTPUT:  Returns with the actual number of bytes stored into the buffer. If this number     *
 *          is less than that requested, then this indicates that the data source has been     *
 *          exhausted.                                                                         *
 *                                                                                             *
 * WARNINGS:   none                                                                            *
 *                                                                                             *
 * HISTORY:                                                                                    *
 *   07/04/1996 JLB : Created.                                                                 *
 *=============================================================================================*/
int LZOStraw::Get(void * destbuf, int slen)
{
    assert(Buffer != NULL);
 
    int total = 0;
 
    /*
    **  Verify parameters for legality.
    */
    if (destbuf == NULL || slen < 1) {
        return(0);
    }
 
    while (slen > 0) {
 
        /*
        **  Copy as much data is requested and available into the desired
        **  destination buffer.
        */
        if (Counter) {
            int len = (slen < Counter) ? slen : Counter;
            if (Control == DECOMPRESS) {
                memmove(destbuf, &Buffer[BlockHeader.UncompCount-Counter], len);
            } else {
                memmove(destbuf, &Buffer2[(BlockHeader.CompCount+sizeof(BlockHeader))-Counter], len);
            }
            destbuf = ((char *)destbuf) + len;
            slen -= len;
            Counter -= len;
            total += len;
        }
        if (slen == 0) break;
 
        if (Control == DECOMPRESS) {
            int incount = Straw::Get(&BlockHeader, sizeof(BlockHeader));
            if (incount != sizeof(BlockHeader)) break;
 
            char *staging_buffer = new char [BlockHeader.CompCount];
            incount = Straw::Get(staging_buffer, BlockHeader.CompCount);
            if (incount != BlockHeader.CompCount) break;
            unsigned int length = sizeof(Buffer);
            lzo1x_decompress ((unsigned char*)staging_buffer, BlockHeader.CompCount, (unsigned char*)Buffer, &length, NULL);
            delete [] staging_buffer;
            Counter = BlockHeader.UncompCount;
        } else {
            BlockHeader.UncompCount = (unsigned short)Straw::Get(Buffer, BlockSize);
            if (BlockHeader.UncompCount == 0) break;
            char *dictionary = new char [64*1024];
            unsigned int length = sizeof (Buffer2) - sizeof (BlockHeader);
            lzo1x_1_compress ((unsigned char*)Buffer, BlockHeader.UncompCount, (unsigned char*)(&Buffer2[sizeof(BlockHeader)]), &length, dictionary);
            BlockHeader.CompCount = (unsigned short)length;
            delete [] dictionary;
            memmove(Buffer2, &BlockHeader, sizeof(BlockHeader));
            Counter = BlockHeader.CompCount+sizeof(BlockHeader);
        }
    }
 
    return(total);
}