128 lines
2.7 KiB
C++
128 lines
2.7 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "ultima/ultima4/filesys/rle.h"
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namespace Ultima {
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namespace Ultima4 {
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/**
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* Decompress an RLE encoded file.
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*/
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long rleDecompressFile(Common::ReadStream *in, long inlen, void **out) {
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void *indata;
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long outlen;
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/* input file should be longer than 0 bytes */
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if (inlen <= 0)
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return -1;
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/* load compressed file into memory */
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indata = malloc(inlen);
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in->read(indata, inlen);
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outlen = rleDecompressMemory(indata, inlen, out);
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free(indata);
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return outlen;
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}
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long rleDecompressMemory(void *in, long inlen, void **out) {
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byte *indata, *outdata;
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long outlen;
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/* input should be longer than 0 bytes */
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if (inlen <= 0)
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return -1;
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indata = (byte *)in;
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/* determine decompressed file size */
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outlen = rleGetDecompressedSize(indata, inlen);
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if (outlen <= 0)
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return -1;
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/* decompress file from inlen to outlen */
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outdata = (byte *) malloc(outlen);
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rleDecompress(indata, inlen, outdata, outlen);
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*out = outdata;
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return outlen;
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}
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/**
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* Determine the uncompressed size of RLE compressed data.
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*/
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long rleGetDecompressedSize(byte *indata, long inlen) {
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byte *p;
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byte ch, count;
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long len = 0;
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p = indata;
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while ((p - indata) < inlen) {
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ch = *p++;
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if (ch == RLE_RUNSTART) {
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count = *p++;
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p++;
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len += count;
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} else
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len++;
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}
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return len;
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}
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/**
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* Decompress a block of RLE encoded memory.
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*/
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long rleDecompress(byte *indata, long inlen, byte *outdata, long outlen) {
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int i;
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byte *p, *q;
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byte ch, count, val;
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p = indata;
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q = outdata;
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while ((p - indata) < inlen) {
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ch = *p++;
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if (ch == RLE_RUNSTART) {
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count = *p++;
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val = *p++;
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for (i = 0; i < count; i++) {
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*q++ = val;
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if ((q - outdata) >= outlen)
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break;
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}
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} else {
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*q++ = ch;
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if ((q - outdata) >= outlen)
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break;
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}
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}
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return q - outdata;
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}
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} // End of namespace Ultima4
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} // End of namespace Ultima
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