mirror of
https://github.com/libretro/scummvm.git
synced 2024-12-30 14:14:43 +00:00
101 lines
3.0 KiB
C++
101 lines
3.0 KiB
C++
/* ScummVM - Graphic Adventure Engine
|
|
*
|
|
* ScummVM is the legal property of its developers, whose names
|
|
* are too numerous to list here. Please refer to the COPYRIGHT
|
|
* file distributed with this source distribution.
|
|
*
|
|
* 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 2
|
|
* 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, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*
|
|
*/
|
|
|
|
#include "groovie/lzss.h"
|
|
|
|
namespace Groovie {
|
|
|
|
#define OUT_BUFF_SIZE 131072
|
|
#define COMP_THRESH 3 // Compression not attempted if string to be compressed is less than 3 long
|
|
|
|
LzssReadStream::LzssReadStream(Common::ReadStream *indata, uint8 lengthmask, uint8 lengthbits) {
|
|
/*
|
|
TODO: Nasty hack. Make a buffer bigger than I'll ever need... probably.
|
|
What should *really* happen is I should define a whole new type of stream
|
|
that gets lzss decompressed on the fly
|
|
*/
|
|
_outLzssBufData = (uint8 *)malloc(OUT_BUFF_SIZE);
|
|
_size = decodeLZSS(indata, lengthmask, lengthbits);
|
|
_pos = 0;
|
|
}
|
|
|
|
LzssReadStream::~LzssReadStream() {
|
|
free(_outLzssBufData);
|
|
}
|
|
|
|
uint32 LzssReadStream::decodeLZSS(Common::ReadStream *in, uint8 lengthmask, uint8 lengthbits) {
|
|
uint32 N = 1 << (16 - lengthbits); /* History buffer size */
|
|
byte *histbuff = new byte[N]; /* History buffer */
|
|
memset(histbuff, 0, N);
|
|
uint32 outstreampos = 0;
|
|
uint32 bufpos = 0;
|
|
|
|
while (!in->eos()) {
|
|
byte flagbyte = in->readByte();
|
|
for (uint32 i = 1; i <= 8; i++) {
|
|
if (!in->eos()) {
|
|
if ((flagbyte & 1) == 0) {
|
|
uint32 offsetlen = in->readUint16LE();
|
|
if (offsetlen == 0) {
|
|
break;
|
|
}
|
|
uint32 length = (offsetlen & lengthmask) + COMP_THRESH;
|
|
uint32 offset = (bufpos - (offsetlen >> lengthbits)) & (N - 1);
|
|
for (uint32 j = 0; j < length; j++) {
|
|
byte tempa = histbuff[(offset + j) & (N - 1)];
|
|
_outLzssBufData[outstreampos++] = tempa;
|
|
histbuff[bufpos] = tempa;
|
|
bufpos = (bufpos + 1) & (N - 1);
|
|
}
|
|
} else {
|
|
byte tempa = in->readByte();
|
|
if (in->eos()) {
|
|
break;
|
|
}
|
|
_outLzssBufData[outstreampos++] = tempa;
|
|
histbuff[bufpos] = tempa;
|
|
bufpos = (bufpos + 1) & (N - 1);
|
|
}
|
|
flagbyte = flagbyte >> 1;
|
|
}
|
|
}
|
|
}
|
|
delete[] histbuff;
|
|
return outstreampos;
|
|
}
|
|
|
|
bool LzssReadStream::eos() const {
|
|
return _pos >= _size;
|
|
}
|
|
|
|
uint32 LzssReadStream::read(void *buf, uint32 size) {
|
|
if (size > _size - _pos)
|
|
size = _size - _pos;
|
|
|
|
memcpy(buf, &_outLzssBufData[_pos], size);
|
|
_pos += size;
|
|
|
|
return size;
|
|
}
|
|
|
|
} // End of Groovie namespace
|