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/* 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 "common/endian.h"
namespace Cruise {
struct UnpackCtx {
int size, datasize;
uint32 crc;
uint32 chk;
byte *dst;
const byte *src;
};
static int rcr(UnpackCtx *uc, int CF) {
int rCF = (uc->chk & 1);
uc->chk >>= 1;
if (CF) {
uc->chk |= 0x80000000;
}
return rCF;
}
static int nextChunk(UnpackCtx *uc) {
int CF = rcr(uc, 0);
if (uc->chk == 0) {
uc->chk = READ_BE_UINT32(uc->src);
uc->src -= 4;
uc->crc ^= uc->chk;
CF = rcr(uc, 1);
}
return CF;
}
static uint16 getCode(UnpackCtx *uc, byte numChunks) {
uint16 c = 0;
while (numChunks--) {
c <<= 1;
if (nextChunk(uc)) {
c |= 1;
}
}
return c;
}
static void unpackHelper1(UnpackCtx *uc, byte numChunks, byte addCount) {
uint16 count = getCode(uc, numChunks) + addCount + 1;
uc->datasize -= count;
while (count--) {
*uc->dst = (byte)getCode(uc, 8);
--uc->dst;
}
}
static void unpackHelper2(UnpackCtx *uc, byte numChunks) {
uint16 i = getCode(uc, numChunks);
uint16 count = uc->size + 1;
uc->datasize -= count;
while (count--) {
*uc->dst = *(uc->dst + i);
--uc->dst;
}
}
bool delphineUnpack(byte *dst, const byte *src, int len) {
UnpackCtx uc;
uc.src = src + len - 4;
uc.datasize = READ_BE_UINT32(uc.src);
uc.src -= 4;
uc.dst = dst + uc.datasize - 1;
uc.size = 0;
uc.crc = READ_BE_UINT32(uc.src);
uc.src -= 4;
uc.chk = READ_BE_UINT32(uc.src);
uc.src -= 4;
uc.crc ^= uc.chk;
do {
if (!nextChunk(&uc)) {
uc.size = 1;
if (!nextChunk(&uc)) {
unpackHelper1(&uc, 3, 0);
} else {
unpackHelper2(&uc, 8);
}
} else {
uint16 c = getCode(&uc, 2);
if (c == 3) {
unpackHelper1(&uc, 8, 8);
} else if (c < 2) {
uc.size = c + 2;
unpackHelper2(&uc, c + 9);
} else {
uc.size = getCode(&uc, 8);
unpackHelper2(&uc, 12);
}
}
} while (uc.datasize > 0);
return uc.crc == 0;
}
} // End of namespace Cruise
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