RedAlert/CODE/LCW.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/LCW.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 : WESTWOOD LIBRARY (PSX)                     *
 *                                                                         *
 *                 File Name : LCWUNCMP.CPP                                *
 *                                                                         *
 *                Programmer : Ian M. Leslie                               *
 *                                                                         *
 *                Start Date : May 17, 1995                                *
 *                                                                         *
 *               Last Update : May 17, 1995    [IML]                       *
 *                                                                         *
 *-------------------------------------------------------------------------*
 * Functions:                                                              *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */


/***************************************************************************
 * LCW_Uncomp -- Decompress an LCW encoded data block.                     *
 *                                                                         *
 * Uncompress data to the following codes in the format b = byte, w = word *
 * n = byte code pulled from compressed data.                              *
 *                                                                         *
 *   Command code, n        |Description                                   *
 * ------------------------------------------------------------------------*
 * n=0xxxyyyy,yyyyyyyy      |short copy back y bytes and run x+3 from dest *
 * n=10xxxxxx,n1,n2,...,nx+1|med length copy the next x+1 bytes from source*
 * n=11xxxxxx,w1            |med copy from dest x+3 bytes from offset w1   *
 * n=11111111,w1,w2         |long copy from dest w1 bytes from offset w2   *
 * n=11111110,w1,b1         |long run of byte b1 for w1 bytes              *
 * n=10000000               |end of data reached                           *
 *                                                                         *
 *                                                                         *
 * INPUT:                                                                  *
 *      void * source ptr                                                  *
 *      void * destination ptr                                             *
 *      unsigned long length of uncompressed data                          *
 *                                                                         *
 *                                                                         *
 * OUTPUT:                                                                 *
 *     unsigned long # of destination bytes written                        *
 *                                                                         *
 * WARNINGS:                                                               *
 *     3rd argument is dummy. It exists to provide cross-platform          *
 *      compatibility. Note therefore that this implementation does not    *
 *      check for corrupt source data by testing the uncompressed length.  *
 *                                                                         *
 * HISTORY:                                                                *
 *    03/20/1995 IML : Created.                                            *
 *=========================================================================*/
int LCW_Uncomp(void const * source, void * dest, unsigned long )
{
	unsigned char * source_ptr, * dest_ptr, * copy_ptr, op_code, data;
	unsigned	  count, * word_dest_ptr, word_data;

	/* Copy the source and destination ptrs. */
	source_ptr = (unsigned char*) source;
	dest_ptr   = (unsigned char*) dest;

	while (1 /*TRUE*/) {

		/* Read in the operation code. */
		op_code = *source_ptr++;

		if (!(op_code & 0x80)) {

			/* Do a short copy from destination. */
			count	 = (op_code >> 4) + 3;
			copy_ptr = dest_ptr - ((unsigned) *source_ptr++ + (((unsigned) op_code & 0x0f) << 8));

			while (count--) *dest_ptr++ = *copy_ptr++;

		} else {

			if (!(op_code & 0x40)) {

				if (op_code == 0x80) {

					/* Return # of destination bytes written. */
					return ((unsigned long) (dest_ptr - (unsigned char*) dest));

				} else {

					/* Do a medium copy from source. */
					count = op_code & 0x3f;

					while (count--) *dest_ptr++ = *source_ptr++;
				}

			} else {

				if (op_code == 0xfe) {

					/* Do a long run. */
					count = *source_ptr + ((unsigned) *(source_ptr + 1) << 8);
					word_data = data = *(source_ptr + 2);
					word_data  = (word_data << 24) + (word_data << 16) + (word_data << 8) + word_data;
					source_ptr += 3;

					copy_ptr = dest_ptr + 4 - ((unsigned) dest_ptr & 0x3);
					count -= (copy_ptr - dest_ptr);
					while (dest_ptr < copy_ptr) *dest_ptr++ = data;

					word_dest_ptr = (unsigned*) dest_ptr;

					dest_ptr += (count & 0xfffffffc);

					while (word_dest_ptr < (unsigned*) dest_ptr) {
						*word_dest_ptr		= word_data;
						*(word_dest_ptr + 1) = word_data;
						word_dest_ptr += 2;
					}

					copy_ptr = dest_ptr + (count & 0x3);
					while (dest_ptr < copy_ptr) *dest_ptr++ = data;

				} else {

					if (op_code == 0xff) {

						/* Do a long copy from destination. */
						count	 = *source_ptr + ((unsigned) *(source_ptr + 1) << 8);
						copy_ptr = (unsigned char*) dest + *(source_ptr + 2) + ((unsigned) *(source_ptr + 3) << 8);
						source_ptr += 4;

						while (count--) *dest_ptr++ = *copy_ptr++;

					} else {

						/* Do a medium copy from destination. */
						count = (op_code & 0x3f) + 3;
						copy_ptr = (unsigned char*) dest + *source_ptr + ((unsigned) *(source_ptr + 1) << 8);
						source_ptr += 2;

						while (count--) *dest_ptr++ = *copy_ptr++;
					}
				}
			}
		}
	}
}