File: reference.cpp

package info (click to toggle)
bowtie2 2.4.2-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 27,104 kB
  • sloc: cpp: 60,331; perl: 7,540; sh: 1,111; python: 949; makefile: 520; ansic: 122
file content (668 lines) | stat: -rw-r--r-- 20,774 bytes parent folder | download | duplicates (4)
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
/*
 * Copyright 2011, Ben Langmead <langmea@cs.jhu.edu>
 *
 * This file is part of Bowtie 2.
 *
 * Bowtie 2 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.
 *
 * Bowtie 2 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 Bowtie 2.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <string>
#include <string.h>
#include "reference.h"
#include "mem_ids.h"

using namespace std;

/**
 * Load from .3.gEbwt_ext/.4.gEbwt_ext Bowtie index files.
 */
BitPairReference::BitPairReference(
	const string& in,
	bool color,
	bool sanity,
	EList<string>* infiles,
	EList<SString<char> >* origs,
	bool infilesSeq,
	bool useMm,
	bool useShmem,
	bool mmSweep,
	bool verbose,
	bool startVerbose) :
	buf_(NULL),
	sanityBuf_(NULL),
	loaded_(true),
	sanity_(sanity),
	useMm_(useMm),
	useShmem_(useShmem),
	verbose_(verbose)
{
	string s3 = in + ".3." + gEbwt_ext;
	string s4 = in + ".4." + gEbwt_ext;
	
	FILE *f3, *f4;
	if((f3 = fopen(s3.c_str(), "rb")) == NULL) {
	    cerr << "Could not open reference-string index file " << s3 << " for reading." << endl;
		cerr << "This is most likely because your index was built with an older version" << endl
		<< "(<= 0.9.8.1) of bowtie-build.  Please re-run bowtie-build to generate a new" << endl
		<< "index (or download one from the Bowtie website) and try again." << endl;
		loaded_ = false;
		return;
	}
    if((f4 = fopen(s4.c_str(), "rb"))  == NULL) {
        cerr << "Could not open reference-string index file " << s4 << " for reading." << endl;
		loaded_ = false;
		return;
	}
#ifdef BOWTIE_MM
    char *mmFile = NULL;
	if(useMm_) {
		if(verbose_ || startVerbose) {
			cerr << "  Memory-mapping reference index file " << s4.c_str() << ": ";
			logTime(cerr);
		}
		struct stat sbuf;
		if (stat(s4.c_str(), &sbuf) == -1) {
			perror("stat");
			cerr << "Error: Could not stat index file " << s4.c_str() << " prior to memory-mapping" << endl;
			throw 1;
		}
		mmFile = (char*)mmap((void *)0, (size_t)sbuf.st_size,
				     PROT_READ, MAP_SHARED, fileno(f4), 0);
		if(mmFile == (void *)(-1) || mmFile == NULL) {
			perror("mmap");
			cerr << "Error: Could not memory-map the index file " << s4.c_str() << endl;
			throw 1;
		}
		if(mmSweep) {
			TIndexOff sum = 0;
			for(off_t i = 0; i < sbuf.st_size; i += 1024) {
				sum += (TIndexOff) mmFile[i];
			}
			if(startVerbose) {
				cerr << "  Swept the memory-mapped ref index file; checksum: " << sum << ": ";
				logTime(cerr);
			}
		}
	}
#endif
	
	// Read endianness sentinel, set 'swap'
	uint32_t one;
	bool swap = false;
	one = readU<int32_t>(f3, swap);
	if(one != 1) {
		if(useMm_) {
			cerr << "Error: Can't use memory-mapped files when the index is the opposite endianness" << endl;
			throw 1;
		}
		assert_eq(0x1000000, one);
		swap = true; // have to endian swap U32s
	}
	
	// Read # records
	TIndexOffU sz;
	sz = readU<TIndexOffU>(f3, swap);
	if(sz == 0) {
		cerr << "Error: number of reference records is 0 in " << s3.c_str() << endl;
		throw 1;
	}
	
	// Read records
	nrefs_ = 0;
	
	// Cumulative count of all unambiguous characters on a per-
	// stretch 8-bit alignment (i.e. count of bytes we need to
	// allocate in buf_)
	TIndexOffU cumsz = 0;
	TIndexOffU cumlen = 0;
	// For each unambiguous stretch...
	for(TIndexOffU i = 0; i < sz; i++) {
		recs_.push_back(RefRecord(f3, swap));
		if(recs_.back().first) {
			// This is the first record for this reference sequence (and the
			// last record for the one before)
			refRecOffs_.push_back((TIndexOffU)recs_.size()-1);
			// refOffs_ links each reference sequence with the total number of
			// unambiguous characters preceding it in the pasted reference
			refOffs_.push_back(cumsz);
			if(nrefs_ > 0) {
				// refLens_ links each reference sequence with the total number
				// of ambiguous and unambiguous characters in it.
				refLens_.push_back(cumlen);
			}
			cumlen = 0;
			nrefs_++;
		} else if(i == 0) {
			cerr << "First record in reference index file was not marked as "
			     << "'first'" << endl;
			throw 1;
		}
		cumUnambig_.push_back(cumsz);
		cumRefOff_.push_back(cumlen);
		cumsz += recs_.back().len;
		cumlen += recs_.back().off;
		cumlen += recs_.back().len;
	}
	if(verbose_ || startVerbose) {
		cerr << "Read " << nrefs_ << " reference strings from "
		     << sz << " records: ";
		logTime(cerr);
	}
	// Store a cap entry for the end of the last reference seq
	refRecOffs_.push_back((TIndexOffU)recs_.size());
	refOffs_.push_back(cumsz);
	refLens_.push_back(cumlen);
	cumUnambig_.push_back(cumsz);
	cumRefOff_.push_back(cumlen);
	bufSz_ = cumsz;
	assert_eq(nrefs_, refLens_.size());
	assert_eq(sz, recs_.size());
	if (f3 != NULL) fclose(f3); // done with .3.gEbwt_ext file
	// Round cumsz up to nearest byte boundary
	if((cumsz & 3) != 0) {
		cumsz += (4 - (cumsz & 3));
	}
	bufAllocSz_ = cumsz >> 2;
	assert_eq(0, cumsz & 3); // should be rounded up to nearest 4
	if(useMm_) {
#ifdef BOWTIE_MM
		buf_ = (uint8_t*)mmFile;
		if(sanity_) {
			FILE *ftmp = fopen(s4.c_str(), "rb");
			sanityBuf_ = new uint8_t[cumsz >> 2];
			size_t ret = fread(sanityBuf_, 1, cumsz >> 2, ftmp);
			if(ret != (cumsz >> 2)) {
				cerr << "Only read " << ret << " bytes (out of " << (cumsz >> 2) << ") from reference index file " << s4.c_str() << endl;
				throw 1;
			}
			fclose(ftmp);
			for(size_t i = 0; i < (cumsz >> 2); i++) {
				assert_eq(sanityBuf_[i], buf_[i]);
			}
		}
#else
		cerr << "Shouldn't be at " << __FILE__ << ":" << __LINE__ << " without BOWTIE_MM defined" << endl;
		throw 1;
#endif
	} else {
		bool shmemLeader = true;
		if(!useShmem_) {
			// Allocate a buffer to hold the reference string
			try {
				buf_ = new uint8_t[cumsz >> 2];
				if(buf_ == NULL) throw std::bad_alloc();
			} catch(std::bad_alloc& e) {
				cerr << "Error: Ran out of memory allocating space for the bitpacked reference.  Please" << endl
				<< "re-run on a computer with more memory." << endl;
				throw 1;
			}
		} else {
			shmemLeader = ALLOC_SHARED_U8(
										  (s4 + "[ref]"), (cumsz >> 2), &buf_,
										  "ref", (verbose_ || startVerbose));
		}
		if(shmemLeader) {
			// Open the bitpair-encoded reference file
			FILE *f4 = fopen(s4.c_str(), "rb");
			if(f4 == NULL) {
				cerr << "Could not open reference-string index file " << s4.c_str() << " for reading." << endl;
				cerr << "This is most likely because your index was built with an older version" << endl
				<< "(<= 0.9.8.1) of bowtie-build.  Please re-run bowtie-build to generate a new" << endl
				<< "index (or download one from the Bowtie website) and try again." << endl;
				loaded_ = false;
				return;
			}
			// Read the whole thing in
			size_t ret = fread(buf_, 1, cumsz >> 2, f4);
			// Didn't read all of it?
			if(ret != (cumsz >> 2)) {
				cerr << "Only read " << ret << " bytes (out of " << (cumsz >> 2) << ") from reference index file " << s4.c_str() << endl;
				throw 1;
			}
			// Make sure there's no more
			char c;
			ret = fread(&c, 1, 1, f4);
			assert_eq(0, ret); // should have failed
			fclose(f4);
#ifdef BOWTIE_SHARED_MEM
			if(useShmem_) NOTIFY_SHARED(buf_, (cumsz >> 2));
#endif
		} else {
#ifdef BOWTIE_SHARED_MEM
			if(useShmem_) WAIT_SHARED(buf_, (cumsz >> 2));
#endif
		}
	}
	
	// Populate byteToU32_
	bool big = currentlyBigEndian();
	for(int i = 0; i < 256; i++) {
		uint32_t word = 0;
		if(big) {
			word |= ((i >> 0) & 3) << 24;
			word |= ((i >> 2) & 3) << 16;
			word |= ((i >> 4) & 3) << 8;
			word |= ((i >> 6) & 3) << 0;
		} else {
			word |= ((i >> 0) & 3) << 0;
			word |= ((i >> 2) & 3) << 8;
			word |= ((i >> 4) & 3) << 16;
			word |= ((i >> 6) & 3) << 24;
		}
		byteToU32_[i] = word;
	}
	
#ifndef NDEBUG
	if(sanity_) {
		// Compare the sequence we just read from the compact index
		// file to the true reference sequence.
		EList<SString<char> > *os; // for holding references
		EList<SString<char> > osv(DEBUG_CAT); // for holding ref seqs
		EList<SString<char> > osn(DEBUG_CAT); // for holding ref names
		EList<size_t> osvLen(DEBUG_CAT); // for holding ref seq lens
		EList<size_t> osnLen(DEBUG_CAT); // for holding ref name lens
		SStringExpandable<uint32_t> tmp_destU32_;
		if(infiles != NULL) {
			if(infilesSeq) {
				for(size_t i = 0; i < infiles->size(); i++) {
					// Remove initial backslash; that's almost
					// certainly being used to protect the first
					// character of the sequence from getopts (e.g.,
					// when the first char is -)
					if((*infiles)[i].at(0) == '\\') {
						(*infiles)[i].erase(0, 1);
					}
					osv.push_back(SString<char>((*infiles)[i]));
				}
			} else {
				parseFastas(*infiles, osn, osnLen, osv, osvLen);
			}
			os = &osv;
		} else {
			assert(origs != NULL);
			os = origs;
		}
		
		// Go through the loaded reference files base-by-base and
		// sanity check against what we get by calling getBase and
		// getStretch
		for(size_t i = 0; i < os->size(); i++) {
			size_t olen = ((*os)[i]).length();
			size_t olenU32 = (olen + 12) / 4;
			uint32_t *buf = new uint32_t[olenU32];
			uint8_t *bufadj = (uint8_t*)buf;
			bufadj += getStretch(buf, i, 0, olen, tmp_destU32_);
			for(size_t j = 0; j < olen; j++) {
				assert_eq((int)(*os)[i][j], (int)bufadj[j]);
				assert_eq((int)(*os)[i][j], (int)getBase(i, j));
			}
			delete[] buf;
		}
	}
#endif
}

BitPairReference::~BitPairReference() {
	if(buf_ != NULL && !useMm_ && !useShmem_) delete[] buf_;
	if(sanityBuf_ != NULL) delete[] sanityBuf_;
}

/**
 * Return a single base of the reference.  Calling this repeatedly
 * is not an efficient way to retrieve bases from the reference;
 * use loadStretch() instead.
 *
 * This implementation scans linearly through the records for the
 * unambiguous stretches of the target reference sequence.  When
 * there are many records, binary search would be more appropriate.
 */
int BitPairReference::getBase(size_t tidx, size_t toff) const {
	uint64_t reci = refRecOffs_[tidx];   // first record for target reference sequence
	uint64_t recf = refRecOffs_[tidx+1]; // last record (exclusive) for target seq
	assert_gt(recf, reci);
	uint64_t bufOff = refOffs_[tidx];
	uint64_t off = 0;
	// For all records pertaining to the target reference sequence...
	for(uint64_t i = reci; i < recf; i++) {
		assert_geq(toff, off);
		off += recs_[i].off;
		if(toff < off) {
			return 4;
		}
		assert_geq(toff, off);
		uint64_t recOff = off + recs_[i].len;
		if(toff < recOff) {
			toff -= off;
			bufOff += (uint64_t)toff;
			assert_lt(bufOff, bufSz_);
			const uint64_t bufElt = (bufOff) >> 2;
			const uint64_t shift = (bufOff & 3) << 1;
			return ((buf_[bufElt] >> shift) & 3);
		}
		bufOff += recs_[i].len;
		off = recOff;
		assert_geq(toff, off);
	} // end for loop over records
	return 4;
}

/**
 * Load a stretch of the reference string into memory at 'dest'.
 *
 * This implementation scans linearly through the records for the
 * unambiguous stretches of the target reference sequence.  When
 * there are many records, binary search would be more appropriate.
 */
int BitPairReference::getStretchNaive(
	uint32_t *destU32,
	size_t tidx,
	size_t toff,
	size_t count) const
{
	uint8_t *dest = (uint8_t*)destU32;
	uint64_t reci = refRecOffs_[tidx];   // first record for target reference sequence
	uint64_t recf = refRecOffs_[tidx+1]; // last record (exclusive) for target seq
	assert_gt(recf, reci);
	uint64_t cur = 0;
	uint64_t bufOff = refOffs_[tidx];
	uint64_t off = 0;
	// For all records pertaining to the target reference sequence...
	for(uint64_t i = reci; i < recf; i++) {
		assert_geq(toff, off);
		off += recs_[i].off;
		for(; toff < off && count > 0; toff++) {
			dest[cur++] = 4;
			count--;
		}
		if(count == 0) break;
		assert_geq(toff, off);
		if(toff < off + recs_[i].len) {
			bufOff += (TIndexOffU)(toff - off); // move bufOff pointer forward
		} else {
			bufOff += recs_[i].len;
		}
		off += recs_[i].len;
		for(; toff < off && count > 0; toff++) {
			assert_lt(bufOff, bufSz_);
			const uint64_t bufElt = (bufOff) >> 2;
			const uint64_t shift = (bufOff & 3) << 1;
			dest[cur++] = (buf_[bufElt] >> shift) & 3;
			bufOff++;
			count--;
		}
		if(count == 0) break;
		assert_geq(toff, off);
	} // end for loop over records
	// In any chars are left after scanning all the records,
	// they must be ambiguous
	while(count > 0) {
		count--;
		dest[cur++] = 4;
	}
	assert_eq(0, count);
	return 0;
}

/**
 * Load a stretch of the reference string into memory at 'dest'.
 */
int BitPairReference::getStretch(
	uint32_t *destU32,
	size_t tidx,
	size_t toff,
	size_t count
	ASSERT_ONLY(, SStringExpandable<uint32_t>& destU32_2)) const
{
	ASSERT_ONLY(size_t origCount = count);
	ASSERT_ONLY(size_t origToff = toff);
	if(count == 0) return 0;
	uint8_t *dest = (uint8_t*)destU32;
#ifndef NDEBUG
	destU32_2.clear();
	uint8_t *dest_2 = NULL;
	int off2;
	if((rand() % 10) == 0) {
		destU32_2.resize((origCount >> 2) + 2);
		off2 = getStretchNaive(destU32_2.wbuf(), tidx, origToff, origCount);
		dest_2 = ((uint8_t*)destU32_2.wbuf()) + off2;
	}
#endif
	destU32[0] = 0x04040404; // Add Ns, which we might end up using later
	uint64_t reci = refRecOffs_[tidx];   // first record for target reference sequence
	uint64_t recf = refRecOffs_[tidx+1]; // last record (exclusive) for target seq
	assert_gt(recf, reci);
	uint64_t cur = 4; // keep a cushion of 4 bases at the beginning
	uint64_t bufOff = refOffs_[tidx];
	uint64_t off = 0;
	int64_t offset = 4;
	bool firstStretch = true;
	ASSERT_ONLY(bool binarySearched = false);
	uint64_t left  = reci;
	uint64_t right = recf;
	uint64_t mid   = 0;
	// For all records pertaining to the target reference sequence...
	for(uint64_t i = reci; i < recf; i++) {
		ASSERT_ONLY(uint64_t origBufOff = bufOff);
		assert_geq(toff, off);
		if (firstStretch && recf > reci + 16){
			// binary search finds smallest i s.t. toff >= cumRefOff_[i]
			while (left < right-1) {
				mid = left + ((right - left) >> 1);
				if (cumRefOff_[mid] <= toff)
					left = mid;
				else
					right = mid;
			}
			off = cumRefOff_[left];
			bufOff = cumUnambig_[left];
			ASSERT_ONLY(origBufOff = bufOff);
			i = left;
			assert(cumRefOff_[i+1] == 0 || cumRefOff_[i+1] > toff);
			ASSERT_ONLY(binarySearched = true);
		}
		off += recs_[i].off; // skip Ns at beginning of stretch
		assert_gt(count, 0);
		if(toff < off) {
			size_t cpycnt = min((size_t)(off - toff), count);
			memset(&dest[cur], 4, cpycnt);
			count -= cpycnt;
			toff += cpycnt;
			cur += cpycnt;
			if(count == 0) break;
		}
		assert_geq(toff, off);
		if(toff < off + recs_[i].len) {
			bufOff += toff - off; // move bufOff pointer forward
		} else {
			bufOff += recs_[i].len;
		}
		off += recs_[i].len;
		assert(off == cumRefOff_[i+1] || cumRefOff_[i+1] == 0);
		assert(!binarySearched || toff < off);
		if(toff < off) {
			if(firstStretch) {
				if(toff + 8 < off && count > 8) {
					// We already added some Ns, so we have to do
					// a fixup at the beginning of the buffer so
					// that we can start clobbering at cur >> 2
					if(cur & 3) {
						offset -= (cur & 3);
					}
					uint64_t curU32 = cur >> 2;
					// Do the initial few bases
					if(bufOff & 3) {
						const uint64_t bufElt = (bufOff) >> 2;
						const int64_t low2 = bufOff & 3;
						// Lots of cache misses on the following line
						destU32[curU32] = byteToU32_[buf_[bufElt]];
						for(int j = 0; j < low2; j++) {
							((char *)(&destU32[curU32]))[j] = 4;
						}
						curU32++;
						offset += low2;
						const int64_t chars = 4 - low2;
						count -= chars;
						bufOff += chars;
						toff += chars;
					}
					assert_eq(0, bufOff & 3);
					uint64_t bufOffU32 = bufOff >> 2;
					uint64_t countLim = count >> 2;
					uint64_t offLim = ((off - (toff + 4)) >> 2);
					uint64_t lim = min(countLim, offLim);
					// Do the fast thing for as far as possible
					for(uint64_t j = 0; j < lim; j++) {
						// Lots of cache misses on the following line
						destU32[curU32] = byteToU32_[buf_[bufOffU32++]];
#ifndef NDEBUG
						if(dest_2 != NULL) {
							assert_eq(dest[(curU32 << 2) + 0], dest_2[(curU32 << 2) - offset + 0]);
							assert_eq(dest[(curU32 << 2) + 1], dest_2[(curU32 << 2) - offset + 1]);
							assert_eq(dest[(curU32 << 2) + 2], dest_2[(curU32 << 2) - offset + 2]);
							assert_eq(dest[(curU32 << 2) + 3], dest_2[(curU32 << 2) - offset + 3]);
						}
#endif
						curU32++;
					}
					toff += (lim << 2);
					assert_leq(toff, off);
					assert_leq((lim << 2), count);
					count -= (lim << 2);
					bufOff = bufOffU32 << 2;
					cur = curU32 << 2;
				}
				// Do the slow thing for the rest
				for(; toff < off && count > 0; toff++) {
					assert_lt(bufOff, bufSz_);
					const uint64_t bufElt = (bufOff) >> 2;
					const uint64_t shift = (bufOff & 3) << 1;
					dest[cur++] = (buf_[bufElt] >> shift) & 3;
					bufOff++;
					count--;
				}
				firstStretch = false;
			} else {
				// Do the slow thing
				for(; toff < off && count > 0; toff++) {
					assert_lt(bufOff, bufSz_);
					const uint64_t bufElt = (bufOff) >> 2;
					const uint64_t shift = (bufOff & 3) << 1;
					dest[cur++] = (buf_[bufElt] >> shift) & 3;
					bufOff++;
					count--;
				}
			}
		}
		if(count == 0) break;
		assert_eq(recs_[i].len, bufOff - origBufOff);
		assert_geq(toff, off);
	} // end for loop over records
	// In any chars are left after scanning all the records,
	// they must be ambiguous
	while(count > 0) {
		count--;
		dest[cur++] = 4;
	}
	assert_eq(0, count);
	return (int)offset;
}


/**
 * Parse the input fasta files, populating the szs list and writing the
 * .3.gEbwt_ext and .4.gEbwt_ext portions of the index as we go.
 */
pair<size_t, size_t>
BitPairReference::szsFromFasta(
	EList<FileBuf*>& is,
	const string& outfile,
	bool bigEndian,
	const RefReadInParams& refparams,
	EList<RefRecord>& szs,
	bool sanity)
{
	RefReadInParams parms = refparams;
	std::pair<size_t, size_t> sztot;
	if(!outfile.empty()) {
		string file3 = outfile + ".3." + gEbwt_ext;
		string file4 = outfile + ".4." + gEbwt_ext;
		// Open output stream for the '.3.gEbwt_ext' file which will
		// hold the size records.
		ofstream fout3(file3.c_str(), ios::binary);
		if(!fout3.good()) {
			cerr << "Could not open index file for writing: \"" << file3.c_str() << "\"" << endl
				 << "Please make sure the directory exists and that permissions allow writing by" << endl
				 << "Bowtie." << endl;
			throw 1;
		}
		BitpairOutFileBuf bpout(file4.c_str());
		// Read in the sizes of all the unambiguous stretches of the genome
		// into a vector of RefRecords.  The input streams are reset once
		// it's done.
		writeU<int32_t>(fout3, 1, bigEndian); // endianness sentinel
		bool color = parms.color;
		if(color) {
			parms.color = false;
			// Make sure the .3.gEbwt_ext and .4.gEbwt_ext files contain
			// nucleotides; not colors
			TIndexOff numSeqs = 0;
			ASSERT_ONLY(std::pair<size_t, size_t> sztot2 =)
			fastaRefReadSizes(is, szs, parms, &bpout, numSeqs);
			parms.color = true;
			writeU<TIndexOffU>(fout3, (TIndexOffU)szs.size(), bigEndian); // write # records
			for(size_t i = 0; i < szs.size(); i++) {
				szs[i].write(fout3, bigEndian);
			}
			szs.clear();
			// Now read in the colorspace size records; these are
			// the ones that were indexed
			TIndexOff numSeqs2 = 0;
			sztot = fastaRefReadSizes(is, szs, parms, NULL, numSeqs2);
			assert_eq(numSeqs, numSeqs2);
			assert_eq(sztot2.second, sztot.second + numSeqs);
		} else {
			TIndexOff numSeqs = 0;
			sztot = fastaRefReadSizes(is, szs, parms, &bpout, numSeqs);
			writeU<TIndexOffU>(fout3, (TIndexOffU)szs.size(), bigEndian); // write # records
			for(size_t i = 0; i < szs.size(); i++) szs[i].write(fout3, bigEndian);
		}
		if(sztot.first == 0) {
			cerr << "Error: No unambiguous stretches of characters in the input.  Aborting..." << endl;
			throw 1;
		}
		assert_gt(sztot.first, 0);
		assert_gt(sztot.second, 0);
		bpout.close();
		fout3.close();
	} else {
		// Read in the sizes of all the unambiguous stretches of the
		// genome into a vector of RefRecords
		TIndexOff numSeqs = 0;
		sztot = fastaRefReadSizes(is, szs, parms, NULL, numSeqs);
#ifndef NDEBUG
		if(parms.color) {
			parms.color = false;
			EList<RefRecord> szs2(EBWTB_CAT);
			TIndexOff numSeqs2 = 0;
			ASSERT_ONLY(std::pair<size_t, size_t> sztot2 =)
			fastaRefReadSizes(is, szs2, parms, NULL, numSeqs2);
			assert_eq(numSeqs, numSeqs2);
			// One less color than base
			assert_geq(sztot2.second, sztot.second + numSeqs);
			parms.color = true;
		}
#endif
	}
	return sztot;
}