aboutsummaryrefslogtreecommitdiff
path: root/engines/sci/scicore/decompressor.cpp
blob: ff8fa4a4454853e7becc6cadf08a76c3302c455d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
/* 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.
 *
 * $URL$
 * $Id$
 *
 */

// Resource library

#include <common/util.h>
#include <common/endian.h>
#include <common/debug.h>
#include "sci/scicore/decompressor.h"
#include "sci/sci.h"

#define _SCI_DECOMPRESS_DEBUG
namespace Sci {

int Decompressor::unpack(Common::ReadStream *src, Common::WriteStream *dest, uint32 nPacked,
                         uint32 nUnpacked) {
	return copyBytes(src, dest, nPacked);
}

int Decompressor::copyBytes(Common::ReadStream *src, Common::WriteStream *dest, uint32 nSize) {
	byte buff[1024];
	uint32 chunk;
	while (nSize && !src->ioFailed() && !dest->ioFailed()) {
		chunk = MIN<uint32>(1024, nSize);
		src->read(buff, chunk);
		dest->write(buff, chunk);
		nSize -= chunk;
	}
	return src->ioFailed() || dest->ioFailed() ? 1 : 0;
}
void Decompressor::init(Common::ReadStream *src, Common::WriteStream *dest, uint32 nPacked,
                        uint32 nUnpacked) {
	_src = src;
	_dest = dest;
	_szPacked = nPacked;
	_szUnpacked = nUnpacked;
	_nBits = 0;
	_dwRead = _dwWrote = 0;
	_dwBits = 0;
}

void Decompressor::fetchBits() {
	while (_nBits <= 24) {
		_dwBits |= ((uint32)_src->readByte()) << (24 - _nBits);
		_nBits += 8;
		_dwRead++;
	}
}

bool Decompressor::getBit() {
	// fetching more bits to _dwBits buffer
	if (_nBits == 0)
		fetchBits();
	bool b = _dwBits & 0x80000000;
	_dwBits <<= 1;
	_nBits--;
	return b;
}

uint32 Decompressor::getBits(int n) {
	// fetching more data to buffer if needed
	if (_nBits < n)
		fetchBits();
	uint32 ret = _dwBits >> (32 - n);
	_dwBits <<= n;
	_nBits -= n;
	return ret;
}

byte Decompressor::getByte() {
	return getBits(8);
}

void Decompressor::putByte(byte b) {
	_dest->writeByte(b);
	_dwWrote++;
}
//-------------------------------
//  Huffman decompressor
//-------------------------------
int DecompressorHuffman::unpack(Common::ReadStream *src, Common::WriteStream *dest, uint32 nPacked,
                                uint32 nUnpacked) {
	init(src, dest, nPacked, nUnpacked);

	byte numnodes;
	int16 c;
	uint16 terminator;

	numnodes = _src->readByte();
	terminator = _src->readByte() | 0x100;
	_nodes = (byte *)malloc(numnodes << 1);
	_src->read(_nodes, numnodes << 1);

	while ((c = getc2()) != terminator && (c >= 0) && (_szUnpacked-- > 0))
		putByte(c);

	free(_nodes);
	return _dwWrote ? 0 : 1;
}

int16 DecompressorHuffman::getc2() {
	byte *node = _nodes;
	int16 next;
	while (node[1]) {
		if (getBit()) {
			next = node[1] & 0x0F; // use lower 4 bits
			if (next == 0)
				return getByte() | 0x100;
		} else
			next = node[1] >> 4; // use higher 4 bits
		node += next << 1;
	}
	return (int16)(*node | (node[1] << 8));
}


//-------------------------------
// LZW-like Decompressor
//-------------------------------
void DecompressorComp3::init(Common::ReadStream *src, Common::WriteStream *dest, uint32 nPacked, uint32 nUnpacked) {
	Decompressor::init(src, dest, nPacked, nUnpacked);

	_lastchar = _lastbits = _stakptr = 0;
	_numbits = 9;
	_curtoken = 0x102;
	_endtoken = 0x1ff;
	memset(_tokens, 0, sizeof(_tokens));
}

int DecompressorComp3::unpack(Common::ReadStream *src, Common::WriteStream *dest, uint32 nPacked,
                              uint32 nUnpacked) {
	byte *buffer = NULL;
	byte *buffer2 = NULL;
	Common::MemoryWriteStream *pBuff = NULL;
	Common::MemoryReadStream *pBuffIn = NULL;

	switch (_compression) {
	case kComp3: // Comp3 compression
		return doUnpack(src, dest, nPacked, nUnpacked);
		break;
	case kComp3View:
	case kComp3Pic:
		buffer = new byte[nUnpacked];
		pBuff = new Common::MemoryWriteStream(buffer, nUnpacked);
		doUnpack(src, pBuff, nPacked, nUnpacked);
		if (_compression == kComp3View) {
			buffer2 = new byte[nUnpacked];
			view_reorder(buffer, buffer2);
			dest->write(buffer2, nUnpacked);
		} else {
			pBuffIn = new Common::MemoryReadStream(buffer, nUnpacked);
			reorderPic(pBuffIn, dest, nUnpacked);
		}
		delete[] buffer2;
		delete[] buffer;
		delete pBuff;
		delete pBuffIn;
		break;
	}
	return 0;
}

int DecompressorComp3::doUnpack(Common::ReadStream *src, Common::WriteStream *dest, uint32 nPacked,
                                uint32 nUnpacked) {
	init(src, dest, nPacked, nUnpacked);

	byte decryptstart = 0;
	uint16 bitstring;
	uint16 token;
	bool bExit = false;

	while (_szUnpacked && !bExit) {
		switch (decryptstart) {
		case 0:
			bitstring = getBits(_numbits);
			if (bitstring == 0x101) {// found end-of-data signal
				bExit = true;
				continue;
			}
			putByte(bitstring);
			_szUnpacked--;
			_lastbits = bitstring;
			_lastchar = (bitstring & 0xff);
			decryptstart = 1;
			break;

		case 1:
			bitstring = getBits(_numbits);
			if (bitstring == 0x101) { // found end-of-data signal
				bExit = true;
				continue;
			}
			if (bitstring == 0x100) { // start-over signal
				_numbits = 9;
				_curtoken = 0x102;
				_endtoken = 0x1ff;
				decryptstart = 0;
				continue;
			}

			token = bitstring;
			if (token >= _curtoken) { // index past current point
				token = _lastbits;
				_stak[_stakptr++] = _lastchar;
			}
			while ((token > 0xff) && (token < 0x1004)) { // follow links back in data
				_stak[_stakptr++] = _tokens[token].data;
				token = _tokens[token].next;
			}
			_lastchar = _stak[_stakptr++] = token & 0xff;
			// put stack in buffer
			while (_stakptr > 0) {
				putByte(_stak[--_stakptr]);
				if (--_szUnpacked == 0) {
					bExit = true;
					continue;
				}
			}
			// put token into record
			if (_curtoken <= _endtoken) {
				_tokens[_curtoken].data = _lastchar;
				_tokens[_curtoken].next = _lastbits;
				_curtoken++;
				if (_curtoken == _endtoken && _numbits != 12) {
					_numbits++;
					_endtoken = (_endtoken << 1) + 1;
				}
			}
			_lastbits = bitstring;
			break;
		}
	}
	return _dwWrote ? 0 : 1;
}

#define PAL_SIZE 1284
#define EXTRA_MAGIC_SIZE 15
#define VIEW_HEADER_COLORS_8BIT 0x80

void DecompressorComp3::decodeRLE(Common::ReadStream *src, Common::WriteStream *dest, byte *pixeldata, uint16 size) {
	int pos = 0;
	byte nextbyte;
	while (pos < size) {
		nextbyte = src->readByte();
		dest->writeByte(nextbyte);
		pos ++;
		switch (nextbyte & 0xC0) {
		case 0x40:
		case 0x00:
			dest->write(pixeldata, nextbyte);
			pixeldata += nextbyte;
			pos += nextbyte;
			break;
		case 0xC0:
			break;
		case 0x80:
			dest->writeByte(*pixeldata++);
			pos++;
			break;
		}
	}
}

void DecompressorComp3::decode_rle(byte **rledata, byte **pixeldata, byte *outbuffer, int size) {
	int pos = 0;
	char nextbyte;
	byte *rd = *rledata;
	byte *ob = outbuffer;
	byte *pd = *pixeldata;

	while (pos < size) {
		nextbyte = *rd++;
		*ob++ = nextbyte;
		pos++;
		switch (nextbyte & 0xC0) {
		case 0x40:
		case 0x00:
			memcpy(ob, pd, nextbyte);
			pd += nextbyte;
			ob += nextbyte;
			pos += nextbyte;
			break;
		case 0xC0:
			break;
		case 0x80:
			nextbyte = *pd++;
			*ob++ = nextbyte;
			pos++;
			break;
		}
	}

	*rledata = rd;
	*pixeldata = pd;
}

/*
 * Does the same this as above, only to determine the length of the compressed
 * source data.
 *
 * Yes, this is inefficient.
 */
int DecompressorComp3::rle_size(byte *rledata, int dsize) {
	int pos = 0;
	char nextbyte;
	int size = 0;

	while (pos < dsize) {
		nextbyte = *(rledata++);
		pos++;
		size++;

		switch (nextbyte & 0xC0) {
		case 0x40:
		case 0x00:
			pos += nextbyte;
			break;
		case 0xC0:
			break;
		case 0x80:
			pos++;
			break;
		}
	}

	return size;
}

void DecompressorComp3::reorderPic(Common::ReadStream *src, Common::WriteStream *dest, int dsize) {
	int view_size, view_start, cdata_size;
	byte viewdata[7];
	byte *cdata = NULL;
	byte *extra = NULL;

	// Setting palette
	dest->writeByte(PIC_OP_OPX);
	dest->writeByte(PIC_OPX_SET_PALETTE);

	for (int i = 0; i < 256; i++) // Palette translation map
		dest->writeByte(i);
	dest->writeUint32LE(0);  //Palette timestamp

	view_size = src->readUint16LE();
	view_start = src->readUint16LE();
	cdata_size = src->readUint16LE();
	src->read(viewdata, sizeof(viewdata));
	// Copy palette colors
	copyBytes(src, dest, 1024);
	// copy drawing opcodes
	if (view_start != PAL_SIZE + 2)
		copyBytes(src, dest, view_start - PAL_SIZE - 2);
	// storing extra opcodes to be pasted after the cel
	if (dsize != view_start + EXTRA_MAGIC_SIZE + view_size) {
		extra = new byte[dsize - view_size - view_start - EXTRA_MAGIC_SIZE];
		src->read(extra, dsize - view_size - view_start - EXTRA_MAGIC_SIZE);
	}
	// Writing picture cel opcode and header
	dest->writeByte(PIC_OP_OPX);
	dest->writeByte(PIC_OPX_EMBEDDED_VIEW);
	dest->writeByte(0);
	dest->writeUint16LE(0);
	dest->writeUint16LE(view_size + 8);
	dest->write(viewdata, sizeof(viewdata));
	dest->writeByte(0);
	// Unpacking RLE cel data
	cdata = new byte[cdata_size];
	src->read(cdata, cdata_size);
	decodeRLE(src, dest, cdata, view_size);
	// writing stored extra opcodes
	if (extra)
		dest->write(extra, dsize - view_size - view_start - EXTRA_MAGIC_SIZE);
	delete[] extra;
	delete[] cdata;
}

void DecompressorComp3::build_cel_headers(byte **seeker, byte **writer, int celindex, int *cc_lengths, int max) {
	for (int c = 0; c < max; c++) {
		memcpy(*writer, *seeker, 6);
		*seeker += 6;
		*writer += 6;
		int w = *((*seeker)++);
		WRITE_LE_UINT16(*writer, w); /* Zero extension */
		*writer += 2;

		*writer += cc_lengths[celindex];
		celindex++;
	}
}

void DecompressorComp3::view_reorder(byte *inbuffer, byte *outbuffer) {
	byte *cellengths;
	int loopheaders;
	int lh_present;
	int lh_mask;
	int pal_offset;
	int cel_total;
	int unknown;
	byte *seeker = inbuffer;
	char celcounts[100];
	byte *writer = outbuffer;
	byte *lh_ptr;
	byte *rle_ptr, *pix_ptr;
	int l, lb, c, celindex, lh_last = -1;
	int chptr;
	int w;
	int *cc_lengths;
	byte **cc_pos;

	/* Parse the main header */
	cellengths = inbuffer + READ_LE_UINT16(seeker) + 2;
	seeker += 2;
	loopheaders = *seeker++;
	lh_present = *seeker++;
	lh_mask = READ_LE_UINT16(seeker);
	seeker += 2;
	unknown = READ_LE_UINT16(seeker);
	seeker += 2;
	pal_offset = READ_LE_UINT16(seeker);
	seeker += 2;
	cel_total = READ_LE_UINT16(seeker);
	seeker += 2;

	cc_pos = (byte **) malloc(sizeof(byte *) * cel_total);
	cc_lengths = (int *) malloc(sizeof(int) * cel_total);

	for (c = 0; c < cel_total; c++)
		cc_lengths[c] = READ_LE_UINT16(cellengths + 2 * c);

	*writer++ = loopheaders;
	*writer++ = VIEW_HEADER_COLORS_8BIT;
	WRITE_LE_UINT16(writer, lh_mask);
	writer += 2;
	WRITE_LE_UINT16(writer, unknown);
	writer += 2;
	WRITE_LE_UINT16(writer, pal_offset);
	writer += 2;

	lh_ptr = writer;
	writer += 2 * loopheaders; /* Make room for the loop offset table */

	pix_ptr = writer;

	memcpy(celcounts, seeker, lh_present);
	seeker += lh_present;

	lb = 1;
	celindex = 0;

	rle_ptr = pix_ptr = cellengths + (2 * cel_total);
	w = 0;

	for (l = 0; l < loopheaders; l++) {
		if (lh_mask & lb) { /* The loop is _not_ present */
			if (lh_last == -1) {
				warning("Error: While reordering view: Loop not present, but can't re-use last loop");
				lh_last = 0;
			}
			WRITE_LE_UINT16(lh_ptr, lh_last);
			lh_ptr += 2;
		} else {
			lh_last = writer - outbuffer;
			WRITE_LE_UINT16(lh_ptr, lh_last);
			lh_ptr += 2;
			WRITE_LE_UINT16(writer, celcounts[w]);
			writer += 2;
			WRITE_LE_UINT16(writer, 0);
			writer += 2;

			/* Now, build the cel offset table */
			chptr = (writer - outbuffer) + (2 * celcounts[w]);

			for (c = 0; c < celcounts[w]; c++) {
				WRITE_LE_UINT16(writer, chptr);
				writer += 2;
				cc_pos[celindex+c] = outbuffer + chptr;
				chptr += 8 + READ_LE_UINT16(cellengths + 2 * (celindex + c));
			}

			build_cel_headers(&seeker, &writer, celindex, cc_lengths, celcounts[w]);

			celindex += celcounts[w];
			w++;
		}

		lb = lb << 1;
	}

	if (celindex < cel_total) {
		warning("View decompression generated too few (%d / %d) headers", celindex, cel_total);
		return;
	}

	/* Figure out where the pixel data begins. */
	for (c = 0; c < cel_total; c++)
		pix_ptr += rle_size(pix_ptr, cc_lengths[c]);

	rle_ptr = cellengths + (2 * cel_total);
	for (c = 0; c < cel_total; c++)
		decode_rle(&rle_ptr, &pix_ptr, cc_pos[c] + 8, cc_lengths[c]);

	*writer++ = 'P';
	*writer++ = 'A';
	*writer++ = 'L';

	for (c = 0; c < 256; c++)
		*writer++ = c;

	seeker -= 4; /* The missing four. Don't ask why. */
	memcpy(writer, seeker, 4*256 + 4);

	free(cc_pos);
	free(cc_lengths);
}

//----------------------------------------------
// LZW 9-12 bits decompressor for SCI0
//----------------------------------------------
int DecompressorLZW::unpack(Common::ReadStream *src, Common::WriteStream *dest, uint32 nPacked,
                            uint32 nUnpacked) {
	init(src, dest, nPacked, nUnpacked);
	byte *buffout = new byte[nUnpacked];
	int error = unpackLZW(buffout);
	dest->write(buffout, nUnpacked);
	delete[] buffout;
	return error;
}

void DecompressorLZW::fetchBits() {
	while (_nBits <= 24) {
		_dwBits |= ((uint32)_src->readByte()) << (_nBits);
		_nBits += 8;
		_dwRead++;
	}
}

uint32 DecompressorLZW::getBits(int n) {
	if (_nBits < n)
		fetchBits();
	uint32 ret = (_dwBits & ~((~0) << n));
	_dwBits >>= n;
	_nBits -= n;
	return ret;
}
int DecompressorLZW::unpackLZW(byte *dest) {
	uint16 bitlen = 9; // no. of bits to read (max. 12)
	uint16 token; // The last received value
	uint16 maxtoken = 0x200; // The biggest token
	uint16 tokenlist[4096]; // pointers to dest[]
	uint16 tokenlengthlist[4096]; // char length of each token
	uint16 tokenctr = 0x102; // no. of registered tokens (starts here)
	uint16 tokenlastlength = 0;
	uint32 destctr = 0;

	while (_dwRead < _szPacked || _nBits) {
		token = getBits(bitlen);

		if (token == 0x101)
			return 0; // terminator
		if (token == 0x100) { // reset command
			maxtoken = 0x200;
			bitlen = 9;
			tokenctr = 0x0102;
		} else {
			{
				int i;
				if (token > 0xff) {
					if (token >= tokenctr) {
#ifdef _SCI_DECOMPRESS_DEBUG
						warning("unpackLZW: Bad token %x", token);
#endif
						// Well this is really bad
						// May be it should throw something like SCI_ERROR_DECOMPRESSION_INSANE
					} else {
						tokenlastlength = tokenlengthlist[token] + 1;
						if (destctr + tokenlastlength > _szUnpacked) {
#ifdef _SCI_DECOMPRESS_DEBUG
							// For me this seems a normal situation, It's necessary to handle it
							warning("unpackLZW: Trying to write beyond the end of array(len=%d, destctr=%d, tok_len=%d)",
							        _szUnpacked, destctr, tokenlastlength);
#endif
							i = 0;
							for (; destctr < _szUnpacked; destctr++) {
								dest[destctr++] = dest [tokenlist[token] + i];
								i++;
							}
						} else
							for (i = 0; i < tokenlastlength; i++) {
								dest[destctr++] = dest[tokenlist[token] + i];
							}
					}
				} else {
					tokenlastlength = 1;
					if (destctr >= _szUnpacked) {
#ifdef _SCI_DECOMPRESS_DEBUG
						warning("unpackLZW: Try to write single byte beyond end of array");
#endif
					} else
						dest[destctr++] = (byte)token;
				}

			}

			if (tokenctr == maxtoken) {
				if (bitlen < 12) {
					bitlen++;
					maxtoken <<= 1;
				} else
					continue; // no further tokens allowed
			}

			tokenlist[tokenctr] = destctr - tokenlastlength;
			tokenlengthlist[tokenctr++] = tokenlastlength;
		}
	}
	return 0;
}

//----------------------------------------------
// DCL decompressor for SCI1.1
//----------------------------------------------
#define HUFFMAN_LEAF 0x40000000
#define BRANCH_SHIFT 12
#define BRANCH_NODE(pos, left, right)  ((left << BRANCH_SHIFT) | (right)),
#define LEAF_NODE(pos, value)  ((value) | HUFFMAN_LEAF),

static int length_tree[] = {
#include "treedef.1"
	0 // We need something witout a comma at the end
};

static int distance_tree[] = {
#include "treedef.2"
	0 // We need something witout a comma at the end
};

static int ascii_tree[] = {
#include "treedef.3"
	0 // We need something witout a comma at the end
};

int DecompressorDCL::unpack(Common::ReadStream *src, Common::WriteStream *dest, uint32 nPacked,
                            uint32 nUnpacked) {
	init(src, dest, nPacked, nUnpacked);

	byte *buffout = new byte[nUnpacked];
	int error = unpackDCL(buffout);
	dest->write(buffout, nUnpacked);
	delete[] buffout;
	return error;
}

void DecompressorDCL::fetchBits() {
	while (_nBits <= 24) {
		_dwBits |= ((uint32)_src->readByte()) << _nBits;
		_nBits += 8;
		_dwRead++;
	}
}

bool DecompressorDCL::getBit() {
	// fetching more bits to _dwBits buffer
	if (_nBits == 0) 
		fetchBits();
	bool b = _dwBits & 0x1;
	_dwBits >>= 1;
	_nBits--;
	return b;
}

uint32 DecompressorDCL::getBits(int n) {
	// fetching more data to buffer if needed
	if (_nBits < n)
		fetchBits();
	uint32 ret = (_dwBits & ~((~0) << n));
	_dwBits >>= n;
	_nBits -= n;
	return ret;
}

int DecompressorDCL::huffman_lookup(int *tree) {
	int pos = 0;
	int bit;

	while (!(tree[pos] & HUFFMAN_LEAF)) {
		bit = getBit();
		debugC(kDebugLevelDclInflate, "[%d]:%d->", pos, bit);
		pos = bit ? tree[pos] & 0xFFF : tree[pos] >> BRANCH_SHIFT;
	}
	debugC(kDebugLevelDclInflate, "=%02x\n", tree[pos] & 0xffff);
	return tree[pos] & 0xFFFF;
}

#define DCL_ASCII_MODE 1

int DecompressorDCL::unpackDCL(byte* dest) {
	int mode, length_param, value;
	uint32 write_pos = 0, val_distance, val_length;

	mode = getByte();
	length_param = getByte();

	if (mode == DCL_ASCII_MODE) {
		warning("DCL-INFLATE: Decompressing ASCII mode (untested)");
	} else if (mode) {
		warning("DCL-INFLATE: Error: Encountered mode %02x, expected 00 or 01\n", mode);
		return -1;
	}

	if (length_param < 3 || length_param > 6)
		warning("Unexpected length_param value %d (expected in [3,6])\n", length_param);

	while (write_pos < _szUnpacked) {
		if (getBit()) { // (length,distance) pair
			value = huffman_lookup(length_tree);

			if (value < 8)
				val_length = value + 2;
			else
				val_length = 8 + (1 << (value - 7)) + getBits(value - 7);

			debugC(kDebugLevelDclInflate, " | ");

			value = huffman_lookup(distance_tree);

			if (val_length == 2)
				val_distance = (value << 2) | getBits(2);
			else
				val_distance = (value << length_param) | getBits(length_param);
			val_distance ++;

			debugC(kDebugLevelDclInflate, "\nCOPY(%d from %d)\n", val_length, val_distance);

			if (val_length + write_pos > _szUnpacked) {
				warning("DCL-INFLATE Error: Write out of bounds while copying %d bytes", val_length);
				return SCI_ERROR_DECOMPRESSION_OVERFLOW;
			}

			if (write_pos < val_distance) {
				warning("DCL-INFLATE Error: Attempt to copy from before beginning of input stream");
				return SCI_ERROR_DECOMPRESSION_INSANE;
			}

			while (val_length) {
				uint32 copy_length = (val_length > val_distance) ? val_distance : val_length;
				assert(val_distance >= copy_length);
				memcpy(dest + write_pos, dest + write_pos - val_distance, copy_length);

				if (Common::isDebugChannelEnabled(kDebugLevelDclInflate)) {
					for (uint32 i = 0; i < copy_length; i++)
						debugC(kDebugLevelDclInflate, "\33[32;31m%02x\33[37;37m ", dest[write_pos + i]);
					debugC(kDebugLevelDclInflate, "\n");
				}

				val_length -= copy_length;
				val_distance += copy_length;
				write_pos += copy_length;
			}

		} else { // Copy byte verbatim
			value = (mode == DCL_ASCII_MODE) ? huffman_lookup(ascii_tree) : getByte();
			dest[write_pos++] = value;
			debugC(kDebugLevelDclInflate, "\33[32;31m%02x \33[37;37m", value);
		}
	}

	return 0;
}

} // End of namespace Sci