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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 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/>.
*
*/
#include "common/compression/powerpacker.h"
#include "common/memstream.h"
#include "common/debug.h"
#include "common/textconsole.h"
namespace Common {
/* the decoder presented here is taken from pplib by Stuart Caie. The
* following statement comes from the original source.
*
* pplib 1.0: a simple PowerPacker decompression and decryption library
* placed in the Public Domain on 2003-09-18 by Stuart Caie.
*/
#define PP_READ_BITS(nbits, var) do { \
bit_cnt = (nbits); (var) = 0; \
while (bits_left < bit_cnt) { \
if (buf < src) return 0; \
bit_buffer |= *--buf << bits_left; \
bits_left += 8; \
} \
bits_left -= bit_cnt; \
while (bit_cnt--) { \
(var) = ((var) << 1) | (bit_buffer & 1); \
bit_buffer >>= 1; \
} \
} while (0)
#define PP_BYTE_OUT(byte) do { \
if (out <= dest) return 0; \
*--out = (byte); written++; \
} while (0)
int PowerPackerStream::ppDecrunchBuffer(const byte *src, byte *dest, uint32 src_len, uint32 dest_len) {
const byte *buf, *off_lens;
byte *out, *dest_end, bits_left = 0, bit_cnt;
uint32 bit_buffer = 0, x, todo, offbits, offset, written = 0;
if (!src || !dest) return 0;
/* set up input and output pointers */
off_lens = src; src = &src[4];
buf = &src[src_len];
out = dest_end = &dest[dest_len];
/* skip the first few bits */
PP_READ_BITS(src[src_len + 3], x);
/* while there are input bits left */
while (written < dest_len) {
PP_READ_BITS(1, x);
if (x == 0) {
/* bit==0: literal, then match. bit==1: just match */
todo = 1; do { PP_READ_BITS(2, x); todo += x; } while (x == 3);
while (todo--) { PP_READ_BITS(8, x); PP_BYTE_OUT(x); }
/* should we end decoding on a literal, break out of the main loop */
if (written == dest_len) break;
}
/* match: read 2 bits for initial offset bitlength / match length */
PP_READ_BITS(2, x);
offbits = off_lens[x];
todo = x+2;
if (x == 3) {
PP_READ_BITS(1, x);
if (x == 0) offbits = 7;
PP_READ_BITS(offbits, offset);
do { PP_READ_BITS(3, x); todo += x; } while (x == 7);
}
else {
PP_READ_BITS(offbits, offset);
}
if (&out[offset] > dest_end) return 0; /* match_overflow */
while (todo--) { x = out[offset]; PP_BYTE_OUT(x); }
}
/* all output bytes written without error */
return 1;
}
uint16 PowerPackerStream::getCrunchType(uint32 signature) {
byte eff = 0;
switch (signature) {
case 0x50503230: /* PP20 */
case 0x5041434b: /* PACK, non-standard header used in amiga floppy ITE. */
eff = 4;
break;
case 0x50504C53: /* PPLS */
error("PPLS crunched files are not supported");
#if 0
eff = 8;
break;
#endif
case 0x50583230: /* PX20 */
error("PX20 crunched files are not supported");
#if 0
eff = 6;
break;
#endif
default:
eff = 0;
}
return eff;
}
PowerPackerStream::PowerPackerStream(Common::SeekableReadStream &stream) {
_dispose = false;
uint32 signature = stream.readUint32BE();
if (getCrunchType(signature) == 0) {
stream.seek(0, SEEK_SET);
_stream = &stream;
return;
}
stream.seek(-4, SEEK_END);
uint32 decrlen = stream.readUint32BE() >> 8;
byte *dest = (byte *)malloc(decrlen);
uint32 crlen = stream.size() - 4;
byte *src = (byte *)malloc(crlen);
stream.seek(4, SEEK_SET);
stream.read(src, crlen);
ppDecrunchBuffer(src, dest, crlen-8, decrlen);
free(src);
_stream = new Common::MemoryReadStream(dest, decrlen, DisposeAfterUse::YES);
_dispose = true;
}
byte *PowerPackerStream::unpackBuffer(const byte *input, uint32 input_len, uint32 &output_len) {
if (input_len < 8) {
output_len = 0;
return nullptr;
}
uint32 signature = READ_BE_UINT32(input);
if (getCrunchType(signature) == 0) {
output_len = 0;
return nullptr;
}
output_len = READ_BE_UINT32(input + input_len - 4) >> 8;
byte *dest = new byte[output_len];
ppDecrunchBuffer(input + 4, dest, input_len - 12, output_len);
return dest;
}
}
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