bitreader.c 31.4 KB
Newer Older
1
/* libFLAC - Free Lossless Audio Codec library
Josh Coalson's avatar
Josh Coalson committed
2
 * Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007,2008,2009  Josh Coalson
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
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Xiph.org Foundation nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if HAVE_CONFIG_H
#  include <config.h>
#endif

36
37
#include <stdlib.h>
#include <string.h>
38
39
40
#include "private/bitmath.h"
#include "private/bitreader.h"
#include "private/crc.h"
41
#include "private/macros.h"
42
#include "FLAC/assert.h"
43
#include "share/compat.h"
44
#include "share/endswap.h"
45
46

/* Things should be fastest when this matches the machine word size */
47
/* WATCHOUT: if you change this you must also change the following #defines down to FLAC__clz_uint32 below to match */
48
/* WATCHOUT: there are a few places where the code will not work unless uint32_t is >= 32 bits wide */
49
/*           also, some sections currently only have fast versions for 4 or 8 bytes per word */
50
51
#define FLAC__BYTES_PER_WORD 4		/* sizeof uint32_t */
#define FLAC__BITS_PER_WORD (8 * FLAC__BYTES_PER_WORD)
52
#define FLAC__WORD_ALL_ONES ((FLAC__uint32)0xffffffff)
53
/* SWAP_BE_WORD_TO_HOST swaps bytes in a uint32_t (which is always big-endian) if necessary to match host byte order */
54
55
56
#if WORDS_BIGENDIAN
#define SWAP_BE_WORD_TO_HOST(x) (x)
#else
57
#define SWAP_BE_WORD_TO_HOST(x) ENDSWAP_32(x)
58
#endif
59

60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
/*
 * This should be at least twice as large as the largest number of words
 * required to represent any 'number' (in any encoding) you are going to
 * read.  With FLAC this is on the order of maybe a few hundred bits.
 * If the buffer is smaller than that, the decoder won't be able to read
 * in a whole number that is in a variable length encoding (e.g. Rice).
 * But to be practical it should be at least 1K bytes.
 *
 * Increase this number to decrease the number of read callbacks, at the
 * expense of using more memory.  Or decrease for the reverse effect,
 * keeping in mind the limit from the first paragraph.  The optimal size
 * also depends on the CPU cache size and other factors; some twiddling
 * may be necessary to squeeze out the best performance.
 */
static const unsigned FLAC__BITREADER_DEFAULT_CAPACITY = 65536u / FLAC__BITS_PER_WORD; /* in words */

76
/* WATCHOUT: assembly routines rely on the order in which these fields are declared */
77
78
79
struct FLAC__BitReader {
	/* any partially-consumed word at the head will stay right-justified as bits are consumed from the left */
	/* any incomplete word at the tail will be left-justified, and bytes from the read callback are added on the right */
80
	uint32_t *buffer;
81
82
83
	unsigned capacity; /* in words */
	unsigned words; /* # of completed words in buffer */
	unsigned bytes; /* # of bytes in incomplete word at buffer[words] */
84
85
	unsigned consumed_words; /* #words ... */
	unsigned consumed_bits; /* ... + (#bits of head word) already consumed from the front of buffer */
86
87
88
89
	unsigned read_crc16; /* the running frame CRC */
	unsigned crc16_align; /* the number of bits in the current consumed word that should not be CRC'd */
	FLAC__BitReaderReadCallback read_callback;
	void *client_data;
90
	FLAC__CPUInfo cpu_info;
91
92
};

93
static inline void crc16_update_word_(FLAC__BitReader *br, uint32_t word)
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
{
	register unsigned crc = br->read_crc16;
#if FLAC__BYTES_PER_WORD == 4
	switch(br->crc16_align) {
		case  0: crc = FLAC__CRC16_UPDATE((unsigned)(word >> 24), crc);
		case  8: crc = FLAC__CRC16_UPDATE((unsigned)((word >> 16) & 0xff), crc);
		case 16: crc = FLAC__CRC16_UPDATE((unsigned)((word >> 8) & 0xff), crc);
		case 24: br->read_crc16 = FLAC__CRC16_UPDATE((unsigned)(word & 0xff), crc);
	}
#elif FLAC__BYTES_PER_WORD == 8
	switch(br->crc16_align) {
		case  0: crc = FLAC__CRC16_UPDATE((unsigned)(word >> 56), crc);
		case  8: crc = FLAC__CRC16_UPDATE((unsigned)((word >> 48) & 0xff), crc);
		case 16: crc = FLAC__CRC16_UPDATE((unsigned)((word >> 40) & 0xff), crc);
		case 24: crc = FLAC__CRC16_UPDATE((unsigned)((word >> 32) & 0xff), crc);
		case 32: crc = FLAC__CRC16_UPDATE((unsigned)((word >> 24) & 0xff), crc);
		case 40: crc = FLAC__CRC16_UPDATE((unsigned)((word >> 16) & 0xff), crc);
		case 48: crc = FLAC__CRC16_UPDATE((unsigned)((word >> 8) & 0xff), crc);
		case 56: br->read_crc16 = FLAC__CRC16_UPDATE((unsigned)(word & 0xff), crc);
	}
#else
	for( ; br->crc16_align < FLAC__BITS_PER_WORD; br->crc16_align += 8)
		crc = FLAC__CRC16_UPDATE((unsigned)((word >> (FLAC__BITS_PER_WORD-8-br->crc16_align)) & 0xff), crc);
	br->read_crc16 = crc;
#endif
	br->crc16_align = 0;
}

122
123
/* would be static except it needs to be called by asm routines */
FLAC__bool bitreader_read_from_client_(FLAC__BitReader *br)
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
{
	unsigned start, end;
	size_t bytes;
	FLAC__byte *target;

	/* first shift the unconsumed buffer data toward the front as much as possible */
	if(br->consumed_words > 0) {
		start = br->consumed_words;
		end = br->words + (br->bytes? 1:0);
		memmove(br->buffer, br->buffer+start, FLAC__BYTES_PER_WORD * (end - start));

		br->words -= start;
		br->consumed_words = 0;
	}

	/*
	 * set the target for reading, taking into account word alignment and endianness
	 */
	bytes = (br->capacity - br->words) * FLAC__BYTES_PER_WORD - br->bytes;
	if(bytes == 0)
		return false; /* no space left, buffer is too small; see note for FLAC__BITREADER_DEFAULT_CAPACITY  */
	target = ((FLAC__byte*)(br->buffer+br->words)) + br->bytes;

147
	/* before reading, if the existing reader looks like this (say uint32_t is 32 bits wide)
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
	 *   bitstream :  11 22 33 44 55            br->words=1 br->bytes=1 (partial tail word is left-justified)
	 *   buffer[BE]:  11 22 33 44 55 ?? ?? ??   (shown layed out as bytes sequentially in memory)
	 *   buffer[LE]:  44 33 22 11 ?? ?? ?? 55   (?? being don't-care)
	 *                               ^^-------target, bytes=3
	 * on LE machines, have to byteswap the odd tail word so nothing is
	 * overwritten:
	 */
#if WORDS_BIGENDIAN
#else
	if(br->bytes)
		br->buffer[br->words] = SWAP_BE_WORD_TO_HOST(br->buffer[br->words]);
#endif

	/* now it looks like:
	 *   bitstream :  11 22 33 44 55            br->words=1 br->bytes=1
	 *   buffer[BE]:  11 22 33 44 55 ?? ?? ??
	 *   buffer[LE]:  44 33 22 11 55 ?? ?? ??
	 *                               ^^-------target, bytes=3
	 */

	/* read in the data; note that the callback may return a smaller number of bytes */
	if(!br->read_callback(target, &bytes, br->client_data))
		return false;

	/* after reading bytes 66 77 88 99 AA BB CC DD EE FF from the client:
	 *   bitstream :  11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF
	 *   buffer[BE]:  11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF ??
	 *   buffer[LE]:  44 33 22 11 55 66 77 88 99 AA BB CC DD EE FF ??
	 * now have to byteswap on LE machines:
	 */
#if WORDS_BIGENDIAN
#else
	end = (br->words*FLAC__BYTES_PER_WORD + br->bytes + bytes + (FLAC__BYTES_PER_WORD-1)) / FLAC__BYTES_PER_WORD;
	for(start = br->words; start < end; start++)
		br->buffer[start] = SWAP_BE_WORD_TO_HOST(br->buffer[start]);
#endif

	/* now it looks like:
	 *   bitstream :  11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF
	 *   buffer[BE]:  11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF ??
	 *   buffer[LE]:  44 33 22 11 88 77 66 55 CC BB AA 99 ?? FF EE DD
	 * finally we'll update the reader values:
	 */
	end = br->words*FLAC__BYTES_PER_WORD + br->bytes + bytes;
	br->words = end / FLAC__BYTES_PER_WORD;
	br->bytes = end % FLAC__BYTES_PER_WORD;

	return true;
}

/***********************************************************************
 *
 * Class constructor/destructor
 *
 ***********************************************************************/

204
FLAC__BitReader *FLAC__bitreader_new(void)
205
{
206
	FLAC__BitReader *br = calloc(1, sizeof(FLAC__BitReader));
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

	/* calloc() implies:
		memset(br, 0, sizeof(FLAC__BitReader));
		br->buffer = 0;
		br->capacity = 0;
		br->words = br->bytes = 0;
		br->consumed_words = br->consumed_bits = 0;
		br->read_callback = 0;
		br->client_data = 0;
	*/
	return br;
}

void FLAC__bitreader_delete(FLAC__BitReader *br)
{
	FLAC__ASSERT(0 != br);

	FLAC__bitreader_free(br);
	free(br);
}

/***********************************************************************
 *
 * Public class methods
 *
 ***********************************************************************/

234
FLAC__bool FLAC__bitreader_init(FLAC__BitReader *br, FLAC__CPUInfo cpu, FLAC__BitReaderReadCallback rcb, void *cd)
235
236
237
238
239
240
{
	FLAC__ASSERT(0 != br);

	br->words = br->bytes = 0;
	br->consumed_words = br->consumed_bits = 0;
	br->capacity = FLAC__BITREADER_DEFAULT_CAPACITY;
241
	br->buffer = malloc(sizeof(uint32_t) * br->capacity);
242
243
244
245
	if(br->buffer == 0)
		return false;
	br->read_callback = rcb;
	br->client_data = cd;
246
	br->cpu_info = cpu;
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

	return true;
}

void FLAC__bitreader_free(FLAC__BitReader *br)
{
	FLAC__ASSERT(0 != br);

	if(0 != br->buffer)
		free(br->buffer);
	br->buffer = 0;
	br->capacity = 0;
	br->words = br->bytes = 0;
	br->consumed_words = br->consumed_bits = 0;
	br->read_callback = 0;
	br->client_data = 0;
}

FLAC__bool FLAC__bitreader_clear(FLAC__BitReader *br)
{
	br->words = br->bytes = 0;
	br->consumed_words = br->consumed_bits = 0;
	return true;
}

void FLAC__bitreader_dump(const FLAC__BitReader *br, FILE *out)
{
	unsigned i, j;
	if(br == 0) {
		fprintf(out, "bitreader is NULL\n");
	}
	else {
		fprintf(out, "bitreader: capacity=%u words=%u bytes=%u consumed: words=%u, bits=%u\n", br->capacity, br->words, br->bytes, br->consumed_words, br->consumed_bits);

		for(i = 0; i < br->words; i++) {
			fprintf(out, "%08X: ", i);
			for(j = 0; j < FLAC__BITS_PER_WORD; j++)
				if(i < br->consumed_words || (i == br->consumed_words && j < br->consumed_bits))
					fprintf(out, ".");
				else
					fprintf(out, "%01u", br->buffer[i] & (1 << (FLAC__BITS_PER_WORD-j-1)) ? 1:0);
			fprintf(out, "\n");
		}
		if(br->bytes > 0) {
			fprintf(out, "%08X: ", i);
			for(j = 0; j < br->bytes*8; j++)
				if(i < br->consumed_words || (i == br->consumed_words && j < br->consumed_bits))
					fprintf(out, ".");
				else
					fprintf(out, "%01u", br->buffer[i] & (1 << (br->bytes*8-j-1)) ? 1:0);
			fprintf(out, "\n");
		}
	}
}

void FLAC__bitreader_reset_read_crc16(FLAC__BitReader *br, FLAC__uint16 seed)
{
	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);
	FLAC__ASSERT((br->consumed_bits & 7) == 0);

	br->read_crc16 = (unsigned)seed;
	br->crc16_align = br->consumed_bits;
}

FLAC__uint16 FLAC__bitreader_get_read_crc16(FLAC__BitReader *br)
{
	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);
	FLAC__ASSERT((br->consumed_bits & 7) == 0);
	FLAC__ASSERT(br->crc16_align <= br->consumed_bits);

	/* CRC any tail bytes in a partially-consumed word */
	if(br->consumed_bits) {
321
		const uint32_t tail = br->buffer[br->consumed_words];
322
323
324
325
326
327
		for( ; br->crc16_align < br->consumed_bits; br->crc16_align += 8)
			br->read_crc16 = FLAC__CRC16_UPDATE((unsigned)((tail >> (FLAC__BITS_PER_WORD-8-br->crc16_align)) & 0xff), br->read_crc16);
	}
	return br->read_crc16;
}

328
inline FLAC__bool FLAC__bitreader_is_consumed_byte_aligned(const FLAC__BitReader *br)
329
330
331
332
{
	return ((br->consumed_bits & 7) == 0);
}

333
inline unsigned FLAC__bitreader_bits_left_for_byte_alignment(const FLAC__BitReader *br)
334
335
336
337
{
	return 8 - (br->consumed_bits & 7);
}

338
inline unsigned FLAC__bitreader_get_input_bits_unconsumed(const FLAC__BitReader *br)
339
340
341
342
{
	return (br->words-br->consumed_words)*FLAC__BITS_PER_WORD + br->bytes*8 - br->consumed_bits;
}

343
FLAC__bool FLAC__bitreader_read_raw_uint32(FLAC__BitReader *br, FLAC__uint32 *val, unsigned bits)
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
{
	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);

	FLAC__ASSERT(bits <= 32);
	FLAC__ASSERT((br->capacity*FLAC__BITS_PER_WORD) * 2 >= bits);
	FLAC__ASSERT(br->consumed_words <= br->words);

	/* WATCHOUT: code does not work with <32bit words; we can make things much faster with this assertion */
	FLAC__ASSERT(FLAC__BITS_PER_WORD >= 32);

	if(bits == 0) { /* OPT: investigate if this can ever happen, maybe change to assertion */
		*val = 0;
		return true;
	}

	while((br->words-br->consumed_words)*FLAC__BITS_PER_WORD + br->bytes*8 - br->consumed_bits < bits) {
		if(!bitreader_read_from_client_(br))
			return false;
	}
	if(br->consumed_words < br->words) { /* if we've not consumed up to a partial tail word... */
		/* OPT: taking out the consumed_bits==0 "else" case below might make things faster if less code allows the compiler to inline this function */
		if(br->consumed_bits) {
			/* this also works when consumed_bits==0, it's just a little slower than necessary for that case */
			const unsigned n = FLAC__BITS_PER_WORD - br->consumed_bits;
369
			const uint32_t word = br->buffer[br->consumed_words];
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
			if(bits < n) {
				*val = (word & (FLAC__WORD_ALL_ONES >> br->consumed_bits)) >> (n-bits);
				br->consumed_bits += bits;
				return true;
			}
			*val = word & (FLAC__WORD_ALL_ONES >> br->consumed_bits);
			bits -= n;
			crc16_update_word_(br, word);
			br->consumed_words++;
			br->consumed_bits = 0;
			if(bits) { /* if there are still bits left to read, there have to be less than 32 so they will all be in the next word */
				*val <<= bits;
				*val |= (br->buffer[br->consumed_words] >> (FLAC__BITS_PER_WORD-bits));
				br->consumed_bits = bits;
			}
			return true;
		}
		else {
388
			const uint32_t word = br->buffer[br->consumed_words];
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
			if(bits < FLAC__BITS_PER_WORD) {
				*val = word >> (FLAC__BITS_PER_WORD-bits);
				br->consumed_bits = bits;
				return true;
			}
			/* at this point 'bits' must be == FLAC__BITS_PER_WORD; because of previous assertions, it can't be larger */
			*val = word;
			crc16_update_word_(br, word);
			br->consumed_words++;
			return true;
		}
	}
	else {
		/* in this case we're starting our read at a partial tail word;
		 * the reader has guaranteed that we have at least 'bits' bits
		 * available to read, which makes this case simpler.
		 */
		/* OPT: taking out the consumed_bits==0 "else" case below might make things faster if less code allows the compiler to inline this function */
		if(br->consumed_bits) {
			/* this also works when consumed_bits==0, it's just a little slower than necessary for that case */
			FLAC__ASSERT(br->consumed_bits + bits <= br->bytes*8);
			*val = (br->buffer[br->consumed_words] & (FLAC__WORD_ALL_ONES >> br->consumed_bits)) >> (FLAC__BITS_PER_WORD-br->consumed_bits-bits);
			br->consumed_bits += bits;
			return true;
		}
		else {
			*val = br->buffer[br->consumed_words] >> (FLAC__BITS_PER_WORD-bits);
			br->consumed_bits += bits;
			return true;
		}
	}
}

FLAC__bool FLAC__bitreader_read_raw_int32(FLAC__BitReader *br, FLAC__int32 *val, unsigned bits)
{
	/* OPT: inline raw uint32 code here, or make into a macro if possible in the .h file */
	if(!FLAC__bitreader_read_raw_uint32(br, (FLAC__uint32*)val, bits))
		return false;
	/* sign-extend: */
	*val <<= (32-bits);
	*val >>= (32-bits);
	return true;
}

FLAC__bool FLAC__bitreader_read_raw_uint64(FLAC__BitReader *br, FLAC__uint64 *val, unsigned bits)
{
	FLAC__uint32 hi, lo;

	if(bits > 32) {
		if(!FLAC__bitreader_read_raw_uint32(br, &hi, bits-32))
			return false;
		if(!FLAC__bitreader_read_raw_uint32(br, &lo, 32))
			return false;
		*val = hi;
		*val <<= 32;
		*val |= lo;
	}
	else {
		if(!FLAC__bitreader_read_raw_uint32(br, &lo, bits))
			return false;
		*val = lo;
	}
	return true;
}

454
inline FLAC__bool FLAC__bitreader_read_uint32_little_endian(FLAC__BitReader *br, FLAC__uint32 *val)
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
{
	FLAC__uint32 x8, x32 = 0;

	/* this doesn't need to be that fast as currently it is only used for vorbis comments */

	if(!FLAC__bitreader_read_raw_uint32(br, &x32, 8))
		return false;

	if(!FLAC__bitreader_read_raw_uint32(br, &x8, 8))
		return false;
	x32 |= (x8 << 8);

	if(!FLAC__bitreader_read_raw_uint32(br, &x8, 8))
		return false;
	x32 |= (x8 << 16);

	if(!FLAC__bitreader_read_raw_uint32(br, &x8, 8))
		return false;
	x32 |= (x8 << 24);

	*val = x32;
	return true;
}

FLAC__bool FLAC__bitreader_skip_bits_no_crc(FLAC__BitReader *br, unsigned bits)
{
	/*
	 * OPT: a faster implementation is possible but probably not that useful
	 * since this is only called a couple of times in the metadata readers.
	 */
	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);

	if(bits > 0) {
		const unsigned n = br->consumed_bits & 7;
		unsigned m;
		FLAC__uint32 x;

		if(n != 0) {
494
			m = flac_min(8-n, bits);
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
			if(!FLAC__bitreader_read_raw_uint32(br, &x, m))
				return false;
			bits -= m;
		}
		m = bits / 8;
		if(m > 0) {
			if(!FLAC__bitreader_skip_byte_block_aligned_no_crc(br, m))
				return false;
			bits %= 8;
		}
		if(bits > 0) {
			if(!FLAC__bitreader_read_raw_uint32(br, &x, bits))
				return false;
		}
	}

	return true;
}

FLAC__bool FLAC__bitreader_skip_byte_block_aligned_no_crc(FLAC__BitReader *br, unsigned nvals)
{
	FLAC__uint32 x;

	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);
	FLAC__ASSERT(FLAC__bitreader_is_consumed_byte_aligned(br));

	/* step 1: skip over partial head word to get word aligned */
	while(nvals && br->consumed_bits) { /* i.e. run until we read 'nvals' bytes or we hit the end of the head word */
		if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
			return false;
		nvals--;
	}
	if(0 == nvals)
		return true;
	/* step 2: skip whole words in chunks */
	while(nvals >= FLAC__BYTES_PER_WORD) {
		if(br->consumed_words < br->words) {
			br->consumed_words++;
			nvals -= FLAC__BYTES_PER_WORD;
		}
		else if(!bitreader_read_from_client_(br))
			return false;
	}
	/* step 3: skip any remainder from partial tail bytes */
	while(nvals) {
		if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
			return false;
		nvals--;
	}

	return true;
}

FLAC__bool FLAC__bitreader_read_byte_block_aligned_no_crc(FLAC__BitReader *br, FLAC__byte *val, unsigned nvals)
{
	FLAC__uint32 x;

	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);
	FLAC__ASSERT(FLAC__bitreader_is_consumed_byte_aligned(br));

	/* step 1: read from partial head word to get word aligned */
	while(nvals && br->consumed_bits) { /* i.e. run until we read 'nvals' bytes or we hit the end of the head word */
		if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
			return false;
		*val++ = (FLAC__byte)x;
		nvals--;
	}
	if(0 == nvals)
		return true;
	/* step 2: read whole words in chunks */
	while(nvals >= FLAC__BYTES_PER_WORD) {
		if(br->consumed_words < br->words) {
569
			const uint32_t word = br->buffer[br->consumed_words++];
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
#if FLAC__BYTES_PER_WORD == 4
			val[0] = (FLAC__byte)(word >> 24);
			val[1] = (FLAC__byte)(word >> 16);
			val[2] = (FLAC__byte)(word >> 8);
			val[3] = (FLAC__byte)word;
#elif FLAC__BYTES_PER_WORD == 8
			val[0] = (FLAC__byte)(word >> 56);
			val[1] = (FLAC__byte)(word >> 48);
			val[2] = (FLAC__byte)(word >> 40);
			val[3] = (FLAC__byte)(word >> 32);
			val[4] = (FLAC__byte)(word >> 24);
			val[5] = (FLAC__byte)(word >> 16);
			val[6] = (FLAC__byte)(word >> 8);
			val[7] = (FLAC__byte)word;
#else
			for(x = 0; x < FLAC__BYTES_PER_WORD; x++)
				val[x] = (FLAC__byte)(word >> (8*(FLAC__BYTES_PER_WORD-x-1)));
#endif
			val += FLAC__BYTES_PER_WORD;
			nvals -= FLAC__BYTES_PER_WORD;
		}
		else if(!bitreader_read_from_client_(br))
			return false;
	}
	/* step 3: read any remainder from partial tail bytes */
	while(nvals) {
		if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
			return false;
		*val++ = (FLAC__byte)x;
		nvals--;
	}

	return true;
}

Josh Coalson's avatar
Josh Coalson committed
605
FLAC__bool FLAC__bitreader_read_unary_unsigned(FLAC__BitReader *br, unsigned *val)
606
#if 0 /* slow but readable version */
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
{
	unsigned bit;

	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);

	*val = 0;
	while(1) {
		if(!FLAC__bitreader_read_bit(br, &bit))
			return false;
		if(bit)
			break;
		else
			*val++;
	}
	return true;
}
#else
{
	unsigned i;

	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);

	*val = 0;
	while(1) {
		while(br->consumed_words < br->words) { /* if we've not consumed up to a partial tail word... */
634
			uint32_t b = br->buffer[br->consumed_words] << br->consumed_bits;
635
			if(b) {
636
				i = FLAC__clz_uint32(b);
637
638
639
				*val += i;
				i++;
				br->consumed_bits += i;
640
				if(br->consumed_bits >= FLAC__BITS_PER_WORD) { /* faster way of testing if(br->consumed_bits == FLAC__BITS_PER_WORD) */
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
					crc16_update_word_(br, br->buffer[br->consumed_words]);
					br->consumed_words++;
					br->consumed_bits = 0;
				}
				return true;
			}
			else {
				*val += FLAC__BITS_PER_WORD - br->consumed_bits;
				crc16_update_word_(br, br->buffer[br->consumed_words]);
				br->consumed_words++;
				br->consumed_bits = 0;
				/* didn't find stop bit yet, have to keep going... */
			}
		}
		/* at this point we've eaten up all the whole words; have to try
		 * reading through any tail bytes before calling the read callback.
		 * this is a repeat of the above logic adjusted for the fact we
		 * don't have a whole word.  note though if the client is feeding
		 * us data a byte at a time (unlikely), br->consumed_bits may not
		 * be zero.
		 */
662
		if(br->bytes*8 > br->consumed_bits) {
663
			const unsigned end = br->bytes * 8;
664
			uint32_t b = (br->buffer[br->consumed_words] & (FLAC__WORD_ALL_ONES << (FLAC__BITS_PER_WORD-end))) << br->consumed_bits;
665
			if(b) {
666
				i = FLAC__clz_uint32(b);
667
668
669
670
671
672
673
674
				*val += i;
				i++;
				br->consumed_bits += i;
				FLAC__ASSERT(br->consumed_bits < FLAC__BITS_PER_WORD);
				return true;
			}
			else {
				*val += end - br->consumed_bits;
675
				br->consumed_bits = end;
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
				FLAC__ASSERT(br->consumed_bits < FLAC__BITS_PER_WORD);
				/* didn't find stop bit yet, have to keep going... */
			}
		}
		if(!bitreader_read_from_client_(br))
			return false;
	}
}
#endif

FLAC__bool FLAC__bitreader_read_rice_signed(FLAC__BitReader *br, int *val, unsigned parameter)
{
	FLAC__uint32 lsbs = 0, msbs = 0;
	unsigned uval;

	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);
	FLAC__ASSERT(parameter <= 31);

	/* read the unary MSBs and end bit */
	if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
		return false;

	/* read the binary LSBs */
	if(!FLAC__bitreader_read_raw_uint32(br, &lsbs, parameter))
		return false;

	/* compose the value */
	uval = (msbs << parameter) | lsbs;
	if(uval & 1)
		*val = -((int)(uval >> 1)) - 1;
	else
		*val = (int)(uval >> 1);

	return true;
}

/* this is by far the most heavily used reader call.  it ain't pretty but it's fast */
FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[], unsigned nvals, unsigned parameter)
715
716
717
{
	/* try and get br->consumed_words and br->consumed_bits into register;
	 * must remember to flush them back to *br before calling other
718
719
720
721
722
	 * bitreader functions that use them, and before returning */
	unsigned cwords, words, lsbs, msbs, x, y;
	unsigned ucbits; /* keep track of the number of unconsumed bits in word */
	uint32_t b;
	int *val, *end;
723
724
725
726
727
728

	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);
	/* WATCHOUT: code does not work with <32bit words; we can make things much faster with this assertion */
	FLAC__ASSERT(FLAC__BITS_PER_WORD >= 32);
	FLAC__ASSERT(parameter < 32);
729
	/* the above two asserts also guarantee that the binary part never straddles more than 2 words, so we don't have to loop to read it */
730

731
732
	val = vals;
	end = vals + nvals;
733

734
735
736
737
	if(parameter == 0) {
		while(val < end) {
			/* read the unary MSBs and end bit */
			if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
738
739
				return false;

740
			*val++ = (int)(msbs >> 1) ^ -(int)(msbs & 1);
741
742
		}

743
		return true;
744
	}
745

746
	FLAC__ASSERT(parameter > 0);
747

748
749
	cwords = br->consumed_words;
	words = br->words;
750

751
752
753
754
755
	/* if we've not consumed up to a partial tail word... */
	if(cwords >= words) {
		x = 0;
		goto process_tail;
	}
756

757
758
	ucbits = FLAC__BITS_PER_WORD - br->consumed_bits;
	b = br->buffer[cwords] << br->consumed_bits;  /* keep unconsumed bits aligned to left */
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
792
793
794
795
	while(val < end) {
		/* read the unary MSBs and end bit */
		x = y = FLAC__clz2_uint32(b);
		if(x == FLAC__BITS_PER_WORD) {
			x = ucbits;
			do {
				/* didn't find stop bit yet, have to keep going... */
				crc16_update_word_(br, br->buffer[cwords++]);
				if (cwords >= words)
					goto incomplete_msbs;
				b = br->buffer[cwords];
				y = FLAC__clz2_uint32(b);
				x += y;
			} while(y == FLAC__BITS_PER_WORD);
		}
		b <<= y;
		b <<= 1; /* account for stop bit */
		ucbits = (ucbits - x - 1) % FLAC__BITS_PER_WORD;
		msbs = x;

		/* read the binary LSBs */
		x = b >> (FLAC__BITS_PER_WORD - parameter);
		if(parameter <= ucbits) {
			ucbits -= parameter;
			b <<= parameter;
		} else {
			/* there are still bits left to read, they will all be in the next word */
			crc16_update_word_(br, br->buffer[cwords++]);
			if (cwords >= words)
				goto incomplete_lsbs;
			b = br->buffer[cwords];
			ucbits += FLAC__BITS_PER_WORD - parameter;
			x |= b >> ucbits;
			b <<= FLAC__BITS_PER_WORD - ucbits;
		}
		lsbs = x;
796

797
798
799
800
801
802
803
804
805
806
807
808
809
		/* compose the value */
		x = (msbs << parameter) | lsbs;
		*val++ = (int)(x >> 1) ^ -(int)(x & 1);

		continue;

		/* at this point we've eaten up all the whole words */
process_tail:
		do {
			if(0) {
incomplete_msbs:
				br->consumed_bits = 0;
				br->consumed_words = cwords;
810
			}
811
812
813

			/* read the unary MSBs and end bit */
			if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
814
				return false;
815
816
817
818
819
820
			msbs += x;
			x = ucbits = 0;

			if(0) {
incomplete_lsbs:
				br->consumed_bits = 0;
821
822
				br->consumed_words = cwords;
			}
823

824
825
826
827
			/* read the binary LSBs */
			if(!FLAC__bitreader_read_raw_uint32(br, &lsbs, parameter - ucbits))
				return false;
			lsbs = x | lsbs;
828

829
830
831
832
			/* compose the value */
			x = (msbs << parameter) | lsbs;
			*val++ = (int)(x >> 1) ^ -(int)(x & 1);
			x = 0;
833

834
835
836
837
838
839
			cwords = br->consumed_words;
			words = br->words;
			ucbits = FLAC__BITS_PER_WORD - br->consumed_bits;
			b = br->buffer[cwords] << br->consumed_bits;
		} while(cwords >= words && val < end);
	}
840

841
842
843
844
	if(ucbits == 0 && cwords < words) {
		/* don't leave the head word with no unconsumed bits */
		crc16_update_word_(br, br->buffer[cwords++]);
		ucbits = FLAC__BITS_PER_WORD;
845
	}
846
847
848
849
850

	br->consumed_bits = FLAC__BITS_PER_WORD - ucbits;
	br->consumed_words = cwords;

	return true;
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
}

#if 0 /* UNUSED */
FLAC__bool FLAC__bitreader_read_golomb_signed(FLAC__BitReader *br, int *val, unsigned parameter)
{
	FLAC__uint32 lsbs = 0, msbs = 0;
	unsigned bit, uval, k;

	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);

	k = FLAC__bitmath_ilog2(parameter);

	/* read the unary MSBs and end bit */
	if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
		return false;

	/* read the binary LSBs */
	if(!FLAC__bitreader_read_raw_uint32(br, &lsbs, k))
		return false;

	if(parameter == 1u<<k) {
		/* compose the value */
		uval = (msbs << k) | lsbs;
	}
	else {
		unsigned d = (1 << (k+1)) - parameter;
		if(lsbs >= d) {
			if(!FLAC__bitreader_read_bit(br, &bit))
				return false;
			lsbs <<= 1;
			lsbs |= bit;
			lsbs -= d;
		}
		/* compose the value */
		uval = msbs * parameter + lsbs;
	}

	/* unfold unsigned to signed */
	if(uval & 1)
		*val = -((int)(uval >> 1)) - 1;
	else
		*val = (int)(uval >> 1);

	return true;
}

FLAC__bool FLAC__bitreader_read_golomb_unsigned(FLAC__BitReader *br, unsigned *val, unsigned parameter)
{
	FLAC__uint32 lsbs, msbs = 0;
	unsigned bit, k;

	FLAC__ASSERT(0 != br);
	FLAC__ASSERT(0 != br->buffer);

	k = FLAC__bitmath_ilog2(parameter);

	/* read the unary MSBs and end bit */
	if(!FLAC__bitreader_read_unary_unsigned(br, &msbs))
		return false;

	/* read the binary LSBs */
	if(!FLAC__bitreader_read_raw_uint32(br, &lsbs, k))
		return false;

	if(parameter == 1u<<k) {
		/* compose the value */
		*val = (msbs << k) | lsbs;
	}
	else {
		unsigned d = (1 << (k+1)) - parameter;
		if(lsbs >= d) {
			if(!FLAC__bitreader_read_bit(br, &bit))
				return false;
			lsbs <<= 1;
			lsbs |= bit;
			lsbs -= d;
		}
		/* compose the value */
		*val = msbs * parameter + lsbs;
	}

	return true;
}
#endif /* UNUSED */

/* on return, if *val == 0xffffffff then the utf-8 sequence was invalid, but the return value will be true */
FLAC__bool FLAC__bitreader_read_utf8_uint32(FLAC__BitReader *br, FLAC__uint32 *val, FLAC__byte *raw, unsigned *rawlen)
{
	FLAC__uint32 v = 0;
	FLAC__uint32 x;
	unsigned i;

	if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
		return false;
	if(raw)
		raw[(*rawlen)++] = (FLAC__byte)x;
	if(!(x & 0x80)) { /* 0xxxxxxx */
		v = x;
		i = 0;
	}
	else if(x & 0xC0 && !(x & 0x20)) { /* 110xxxxx */
		v = x & 0x1F;
		i = 1;
	}
	else if(x & 0xE0 && !(x & 0x10)) { /* 1110xxxx */
		v = x & 0x0F;
		i = 2;
	}
	else if(x & 0xF0 && !(x & 0x08)) { /* 11110xxx */
		v = x & 0x07;
		i = 3;
	}
	else if(x & 0xF8 && !(x & 0x04)) { /* 111110xx */
		v = x & 0x03;
		i = 4;
	}
	else if(x & 0xFC && !(x & 0x02)) { /* 1111110x */
		v = x & 0x01;
		i = 5;
	}
	else {
		*val = 0xffffffff;
		return true;
	}
	for( ; i; i--) {
		if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
			return false;
		if(raw)
			raw[(*rawlen)++] = (FLAC__byte)x;
		if(!(x & 0x80) || (x & 0x40)) { /* 10xxxxxx */
			*val = 0xffffffff;
			return true;
		}
		v <<= 6;
		v |= (x & 0x3F);
	}
	*val = v;
	return true;
}

/* on return, if *val == 0xffffffffffffffff then the utf-8 sequence was invalid, but the return value will be true */
FLAC__bool FLAC__bitreader_read_utf8_uint64(FLAC__BitReader *br, FLAC__uint64 *val, FLAC__byte *raw, unsigned *rawlen)
{
	FLAC__uint64 v = 0;
	FLAC__uint32 x;
	unsigned i;

	if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
		return false;
	if(raw)
		raw[(*rawlen)++] = (FLAC__byte)x;
	if(!(x & 0x80)) { /* 0xxxxxxx */
		v = x;
		i = 0;
	}
	else if(x & 0xC0 && !(x & 0x20)) { /* 110xxxxx */
		v = x & 0x1F;
		i = 1;
	}
	else if(x & 0xE0 && !(x & 0x10)) { /* 1110xxxx */
		v = x & 0x0F;
		i = 2;
	}
	else if(x & 0xF0 && !(x & 0x08)) { /* 11110xxx */
		v = x & 0x07;
		i = 3;
	}
	else if(x & 0xF8 && !(x & 0x04)) { /* 111110xx */
		v = x & 0x03;
		i = 4;
	}
	else if(x & 0xFC && !(x & 0x02)) { /* 1111110x */
		v = x & 0x01;
		i = 5;
	}
	else if(x & 0xFE && !(x & 0x01)) { /* 11111110 */
		v = 0;
		i = 6;
	}
	else {
		*val = FLAC__U64L(0xffffffffffffffff);
		return true;
	}
	for( ; i; i--) {
		if(!FLAC__bitreader_read_raw_uint32(br, &x, 8))
			return false;
		if(raw)
			raw[(*rawlen)++] = (FLAC__byte)x;
		if(!(x & 0x80) || (x & 0x40)) { /* 10xxxxxx */
			*val = FLAC__U64L(0xffffffffffffffff);
			return true;
		}
		v <<= 6;
		v |= (x & 0x3F);
	}
	*val = v;
	return true;
}
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062

/* These functions a declared inline in this file but are also callable as
 * externs from elsewhere.
 * According to the C99 sepc, section 6.7.4, simply providing a function
 * prototype in a header file without 'inline' and making the function inline
 * in this file should be sufficient.
 * Unfortunately, the Microsoft VS compiler doesn't pick them up externally. To
 * fix that we add extern declarations here.
 */
extern FLAC__bool FLAC__bitreader_is_consumed_byte_aligned(const FLAC__BitReader *br);
extern unsigned FLAC__bitreader_bits_left_for_byte_alignment(const FLAC__BitReader *br);
extern unsigned FLAC__bitreader_get_input_bits_unconsumed(const FLAC__BitReader *br);
extern FLAC__bool FLAC__bitreader_read_uint32_little_endian(FLAC__BitReader *br, FLAC__uint32 *val);