src/libFLAC/bitwriter.c

   1 /* libFLAC - Free Lossless Audio Codec library
   2  * Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007  Josh Coalson
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  *
   8  * - Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * - Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * - Neither the name of the Xiph.org Foundation nor the names of its
  16  * contributors may be used to endorse or promote products derived from
  17  * this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  22  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  25  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  26  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  27  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #if HAVE_CONFIG_H
  33 #  include <config.h>
  34 #endif
  35
  36 #include <stdlib.h> /* for malloc() */
  37 #include <string.h> /* for memcpy(), memset() */
  38 #ifdef _MSC_VER
  39 #include <winsock.h> /* for ntohl() */
  40 #elif defined FLAC__SYS_DARWIN
  41 #include <machine/endian.h> /* for ntohl() */
  42 #else
  43 #include <netinet/in.h> /* for ntohl() */
  44 #endif
  45 #if 0 /* UNUSED */
  46 #include "private/bitmath.h"
  47 #endif
  48 #include "private/bitwriter.h"
  49 #include "private/crc.h"
  50 #include "FLAC/assert.h"
  51
  52 /* Things should be fastest when this matches the machine word size */
  53 /* WATCHOUT: if you change this you must also change the following #defines down to SWAP_BE_WORD_TO_HOST below to match */
  54 /* WATCHOUT: there are a few places where the code will not work unless bwword is >= 32 bits wide */
  55 typedef FLAC__uint32 bwword;
  56 #define FLAC__BYTES_PER_WORD 4
  57 #define FLAC__BITS_PER_WORD 32
  58 #define FLAC__WORD_ALL_ONES ((FLAC__uint32)0xffffffff)
  59 /* SWAP_BE_WORD_TO_HOST swaps bytes in a bwword (which is always big-endian) if necessary to match host byte order */
  60 #if WORDS_BIGENDIAN
  61 #define SWAP_BE_WORD_TO_HOST(x) (x)
  62 #else
  63 #ifdef _MSC_VER
  64 #define SWAP_BE_WORD_TO_HOST(x) local_swap32_(x)
  65 #else
  66 #define SWAP_BE_WORD_TO_HOST(x) ntohl(x)
  67 #endif
  68 #endif
  69
  70 /*
  71  * The default capacity here doesn't matter too much.  The buffer always grows
  72  * to hold whatever is written to it.  Usually the encoder will stop adding at
  73  * a frame or metadata block, then write that out and clear the buffer for the
  74  * next one.
  75  */
  76 static const unsigned FLAC__BITWRITER_DEFAULT_CAPACITY = 32768u / sizeof(bwword); /* size in words */
  77 /* When growing, increment 4K at a time */
  78 static const unsigned FLAC__BITWRITER_DEFAULT_INCREMENT = 4096u / sizeof(bwword); /* size in words */
  79
  80 #define FLAC__WORDS_TO_BITS(words) ((words) * FLAC__BITS_PER_WORD)
  81 #define FLAC__TOTAL_BITS(bw) (FLAC__WORDS_TO_BITS((bw)->words) + (bw)->bits)
  82
  83 #ifdef min
  84 #undef min
  85 #endif
  86 #define min(x,y) ((x)<(y)?(x):(y))
  87
  88 /* adjust for compilers that can't understand using LLU suffix for uint64_t literals */
  89 #ifdef _MSC_VER
  90 #define FLAC__U64L(x) x
  91 #else
  92 #define FLAC__U64L(x) x##LLU
  93 #endif
  94
  95 #ifndef FLaC__INLINE
  96 #define FLaC__INLINE
  97 #endif
  98
  99 struct FLAC__BitWriter {
 100         bwword *buffer;
 101         bwword accum; /* accumulator; bits are right-justified; when full, accum is appended to buffer */
 102         unsigned capacity; /* capacity of buffer in words */
 103         unsigned words; /* # of complete words in buffer */
 104         unsigned bits; /* # of used bits in accum */
 105 };
 106
 107 #ifdef _MSC_VER
 108 /* OPT: an MSVC built-in would be better */
 109 static _inline FLAC__uint32 local_swap32_(FLAC__uint32 x)
 110 {
 111         x = ((x<<8)&0xFF00FF00) | ((x>>8)&0x00FF00FF);
 112         return (x>>16) | (x<<16);
 113 }
 114 #endif
 115
 116 /* * WATCHOUT: The current implementation only grows the buffer. */
 117 static FLAC__bool bitwriter_grow_(FLAC__BitWriter *bw, unsigned bits_to_add)
 118 {
 119         unsigned new_capacity;
 120         bwword *new_buffer;
 121
 122         FLAC__ASSERT(0 != bw);
 123         FLAC__ASSERT(0 != bw->buffer);
 124
 125         /* calculate total words needed to store 'bits_to_add' additional bits */
 126         new_capacity = bw->words + ((bw->bits + bits_to_add + FLAC__BITS_PER_WORD - 1) / FLAC__BITS_PER_WORD);
 127
 128         /* it's possible (due to pessimism in the growth estimation that
 129          * leads to this call) that we don't actually need to grow
 130          */
 131         if(bw->capacity >= new_capacity)
 132                 return true;
 133
 134         /* round up capacity increase to the nearest FLAC__BITWRITER_DEFAULT_INCREMENT */
 135         if((new_capacity - bw->capacity) % FLAC__BITWRITER_DEFAULT_INCREMENT)
 136                 new_capacity += FLAC__BITWRITER_DEFAULT_INCREMENT - ((new_capacity - bw->capacity) % FLAC__BITWRITER_DEFAULT_INCREMENT);
 137         /* make sure we got everything right */
 138         FLAC__ASSERT(0 == (new_capacity - bw->capacity) % FLAC__BITWRITER_DEFAULT_INCREMENT);
 139         FLAC__ASSERT(new_capacity > bw->capacity);
 140         FLAC__ASSERT(new_capacity >= bw->words + ((bw->bits + bits_to_add + FLAC__BITS_PER_WORD - 1) / FLAC__BITS_PER_WORD));
 141
 142         new_buffer = (bwword*)realloc(bw->buffer, sizeof(bwword)*new_capacity);
 143         if(new_buffer == 0)
 144                 return false;
 145         bw->buffer = new_buffer;
 146         bw->capacity = new_capacity;
 147         return true;
 148 }
 149
 150
 151 /***********************************************************************
 152  *
 153  * Class constructor/destructor
 154  *
 155  ***********************************************************************/
 156
 157 FLAC__BitWriter *FLAC__bitwriter_new(void)
 158 {
 159         FLAC__BitWriter *bw = (FLAC__BitWriter*)calloc(1, sizeof(FLAC__BitWriter));
 160         /* note that calloc() sets all members to 0 for us */
 161         return bw;
 162 }
 163
 164 void FLAC__bitwriter_delete(FLAC__BitWriter *bw)
 165 {
 166         FLAC__ASSERT(0 != bw);
 167
 168         FLAC__bitwriter_free(bw);
 169         free(bw);
 170 }
 171
 172 /***********************************************************************
 173  *
 174  * Public class methods
 175  *
 176  ***********************************************************************/
 177
 178 FLAC__bool FLAC__bitwriter_init(FLAC__BitWriter *bw)
 179 {
 180         FLAC__ASSERT(0 != bw);
 181
 182         bw->words = bw->bits = 0;
 183         bw->capacity = FLAC__BITWRITER_DEFAULT_CAPACITY;
 184         bw->buffer = (bwword*)malloc(sizeof(bwword) * bw->capacity);
 185         if(bw->buffer == 0)
 186                 return false;
 187
 188         return true;
 189 }
 190
 191 void FLAC__bitwriter_free(FLAC__BitWriter *bw)
 192 {
 193         FLAC__ASSERT(0 != bw);
 194
 195         if(0 != bw->buffer)
 196                 free(bw->buffer);
 197         bw->buffer = 0;
 198         bw->capacity = 0;
 199         bw->words = bw->bits = 0;
 200 }
 201
 202 void FLAC__bitwriter_clear(FLAC__BitWriter *bw)
 203 {
 204         bw->words = bw->bits = 0;
 205 }
 206
 207 void FLAC__bitwriter_dump(const FLAC__BitWriter *bw, FILE *out)
 208 {
 209         unsigned i, j;
 210         if(bw == 0) {
 211                 fprintf(out, "bitwriter is NULL\n");
 212         }
 213         else {
 214                 fprintf(out, "bitwriter: capacity=%u words=%u bits=%u total_bits=%u\n", bw->capacity, bw->words, bw->bits, FLAC__TOTAL_BITS(bw));
 215
 216                 for(i = 0; i < bw->words; i++) {
 217                         fprintf(out, "%08X: ", i);
 218                         for(j = 0; j < FLAC__BITS_PER_WORD; j++)
 219                                 fprintf(out, "%01u", bw->buffer[i] & (1 << (FLAC__BITS_PER_WORD-j-1)) ? 1:0);
 220                         fprintf(out, "\n");
 221                 }
 222                 if(bw->bits > 0) {
 223                         fprintf(out, "%08X: ", i);
 224                         for(j = 0; j < bw->bits; j++)
 225                                 fprintf(out, "%01u", bw->accum & (1 << (bw->bits-j-1)) ? 1:0);
 226                         fprintf(out, "\n");
 227                 }
 228         }
 229 }
 230
 231 FLAC__bool FLAC__bitwriter_get_write_crc16(FLAC__BitWriter *bw, FLAC__uint16 *crc)
 232 {
 233         const FLAC__byte *buffer;
 234         size_t bytes;
 235
 236         FLAC__ASSERT((bw->bits & 7) == 0); /* assert that we're byte-aligned */
 237
 238         if(!FLAC__bitwriter_get_buffer(bw, &buffer, &bytes))
 239                 return false;
 240
 241         *crc = (FLAC__uint16)FLAC__crc16(buffer, bytes);
 242         FLAC__bitwriter_release_buffer(bw);
 243         return true;
 244 }
 245
 246 FLAC__bool FLAC__bitwriter_get_write_crc8(FLAC__BitWriter *bw, FLAC__byte *crc)
 247 {
 248         const FLAC__byte *buffer;
 249         size_t bytes;
 250
 251         FLAC__ASSERT((bw->bits & 7) == 0); /* assert that we're byte-aligned */
 252
 253         if(!FLAC__bitwriter_get_buffer(bw, &buffer, &bytes))
 254                 return false;
 255
 256         *crc = FLAC__crc8(buffer, bytes);
 257         FLAC__bitwriter_release_buffer(bw);
 258         return true;
 259 }
 260
 261 FLAC__bool FLAC__bitwriter_is_byte_aligned(const FLAC__BitWriter *bw)
 262 {
 263         return ((bw->bits & 7) == 0);
 264 }
 265
 266 unsigned FLAC__bitwriter_get_input_bits_unconsumed(const FLAC__BitWriter *bw)
 267 {
 268         return FLAC__TOTAL_BITS(bw);
 269 }
 270
 271 FLAC__bool FLAC__bitwriter_get_buffer(FLAC__BitWriter *bw, const FLAC__byte **buffer, size_t *bytes)
 272 {
 273         FLAC__ASSERT((bw->bits & 7) == 0);
 274         /* double protection */
 275         if(bw->bits & 7)
 276                 return false;
 277         /* if we have bits in the accumulator we have to flush those to the buffer first */
 278         if(bw->bits) {
 279                 FLAC__ASSERT(bw->words <= bw->capacity);
 280                 if(bw->words == bw->capacity && !bitwriter_grow_(bw, FLAC__BITS_PER_WORD))
 281                         return false;
 282                 /* append bits as complete word to buffer, but don't change bw->accum or bw->bits */
 283                 bw->buffer[bw->words] = SWAP_BE_WORD_TO_HOST(bw->accum << (FLAC__BITS_PER_WORD-bw->bits));
 284         }
 285         /* now we can just return what we have */
 286         *buffer = (FLAC__byte*)bw->buffer;
 287         *bytes = (FLAC__BYTES_PER_WORD * bw->words) + (bw->bits >> 3);
 288         return true;
 289 }
 290
 291 void FLAC__bitwriter_release_buffer(FLAC__BitWriter *bw)
 292 {
 293         /* nothing to do.  in the future, strict checking of a 'writer-is-in-
 294          * get-mode' flag could be added everywhere and then cleared here
 295          */
 296         (void)bw;
 297 }
 298
 299 FLaC__INLINE FLAC__bool FLAC__bitwriter_write_zeroes(FLAC__BitWriter *bw, unsigned bits)
 300 {
 301         unsigned n;
 302
 303         FLAC__ASSERT(0 != bw);
 304         FLAC__ASSERT(0 != bw->buffer);
 305
 306         if(bits == 0)
 307                 return true;
 308         /* slightly pessimistic size check but faster than "<= bw->words + (bw->bits+bits+FLAC__BITS_PER_WORD-1)/FLAC__BITS_PER_WORD" */
 309         if(bw->capacity <= bw->words + bits && !bitwriter_grow_(bw, bits))
 310                 return false;
 311         /* first part gets to word alignment */
 312         if(bw->bits) {
 313                 n = min(FLAC__BITS_PER_WORD - bw->bits, bits);
 314                 bw->accum <<= n;
 315                 bits -= n;
 316                 bw->bits += n;
 317                 if(bw->bits == FLAC__BITS_PER_WORD) {
 318                         bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum);
 319                         bw->bits = 0;
 320                 }
 321                 else
 322                         return true;
 323         }
 324         /* do whole words */
 325         while(bits >= FLAC__BITS_PER_WORD) {
 326                 bw->buffer[bw->words++] = 0;
 327                 bits -= FLAC__BITS_PER_WORD;
 328         }
 329         /* do any leftovers */
 330         if(bits > 0) {
 331                 bw->accum = 0;
 332                 bw->bits = bits;
 333         }
 334         return true;
 335 }
 336
 337 FLaC__INLINE FLAC__bool FLAC__bitwriter_write_raw_uint32(FLAC__BitWriter *bw, FLAC__uint32 val, unsigned bits)
 338 {
 339         register unsigned left;
 340
 341         /* WATCHOUT: code does not work with <32bit words; we can make things much faster with this assertion */
 342         FLAC__ASSERT(FLAC__BITS_PER_WORD >= 32);
 343
 344         FLAC__ASSERT(0 != bw);
 345         FLAC__ASSERT(0 != bw->buffer);
 346
 347         FLAC__ASSERT(bits <= 32);
 348         if(bits == 0)
 349                 return true;
 350
 351         /* slightly pessimistic size check but faster than "<= bw->words + (bw->bits+bits+FLAC__BITS_PER_WORD-1)/FLAC__BITS_PER_WORD" */
 352         if(bw->capacity <= bw->words + bits && !bitwriter_grow_(bw, bits))
 353                 return false;
 354
 355         left = FLAC__BITS_PER_WORD - bw->bits;
 356         if(bits < left) {
 357                 bw->accum <<= bits;
 358                 bw->accum |= val;
 359                 bw->bits += bits;
 360         }
 361         else if(bw->bits) { /* WATCHOUT: if bw->bits == 0, left==FLAC__BITS_PER_WORD and bw->accum<<=left is a NOP instead of setting to 0 */
 362                 bw->accum <<= left;
 363                 bw->accum |= val >> (bw->bits = bits - left);
 364                 bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum);
 365                 bw->accum = val;
 366         }
 367         else {
 368                 bw->accum = val;
 369                 bw->bits = 0;
 370                 bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(val);
 371         }
 372
 373         return true;
 374 }
 375
 376 FLaC__INLINE FLAC__bool FLAC__bitwriter_write_raw_int32(FLAC__BitWriter *bw, FLAC__int32 val, unsigned bits)
 377 {
 378         /* zero-out unused bits */
 379         if(bits < 32)
 380                 val &= (~(0xffffffff << bits));
 381
 382         return FLAC__bitwriter_write_raw_uint32(bw, (FLAC__uint32)val, bits);
 383 }
 384
 385 FLaC__INLINE FLAC__bool FLAC__bitwriter_write_raw_uint64(FLAC__BitWriter *bw, FLAC__uint64 val, unsigned bits)
 386 {
 387         /* this could be a little faster but it's not used for much */
 388         if(bits > 32) {
 389                 return
 390                         FLAC__bitwriter_write_raw_uint32(bw, (FLAC__uint32)(val>>32), bits-32) &&
 391                         FLAC__bitwriter_write_raw_uint32(bw, (FLAC__uint32)val, 32);
 392         }
 393         else
 394                 return FLAC__bitwriter_write_raw_uint32(bw, (FLAC__uint32)val, bits);
 395 }
 396
 397 FLaC__INLINE FLAC__bool FLAC__bitwriter_write_raw_uint32_little_endian(FLAC__BitWriter *bw, FLAC__uint32 val)
 398 {
 399         /* this doesn't need to be that fast as currently it is only used for vorbis comments */
 400
 401         if(!FLAC__bitwriter_write_raw_uint32(bw, val & 0xff, 8))
 402                 return false;
 403         if(!FLAC__bitwriter_write_raw_uint32(bw, (val>>8) & 0xff, 8))
 404                 return false;
 405         if(!FLAC__bitwriter_write_raw_uint32(bw, (val>>16) & 0xff, 8))
 406                 return false;
 407         if(!FLAC__bitwriter_write_raw_uint32(bw, val>>24, 8))
 408                 return false;
 409
 410         return true;
 411 }
 412
 413 FLaC__INLINE FLAC__bool FLAC__bitwriter_write_byte_block(FLAC__BitWriter *bw, const FLAC__byte vals[], unsigned nvals)
 414 {
 415         unsigned i;
 416
 417         /* this could be faster but currently we don't need it to be since it's only used for writing metadata */
 418         for(i = 0; i < nvals; i++) {
 419                 if(!FLAC__bitwriter_write_raw_uint32(bw, (FLAC__uint32)(vals[i]), 8))
 420                         return false;
 421         }
 422
 423         return true;
 424 }
 425
 426 FLAC__bool FLAC__bitwriter_write_unary_unsigned(FLAC__BitWriter *bw, unsigned val)
 427 {
 428         if(val < 32)
 429                 return FLAC__bitwriter_write_raw_uint32(bw, 1, ++val);
 430         else
 431                 return
 432                         FLAC__bitwriter_write_zeroes(bw, val) &&
 433                         FLAC__bitwriter_write_raw_uint32(bw, 1, 1);
 434 }
 435
 436 unsigned FLAC__bitwriter_rice_bits(FLAC__int32 val, unsigned parameter)
 437 {
 438         FLAC__uint32 uval;
 439
 440         FLAC__ASSERT(parameter < sizeof(unsigned)*8);
 441
 442         /* fold signed to unsigned; actual formula is: negative(v)? -2v-1 : 2v */
 443         uval = (val<<1) ^ (val>>31);
 444
 445         return 1 + parameter + (uval >> parameter);
 446 }
 447
 448 #if 0 /* UNUSED */
 449 unsigned FLAC__bitwriter_golomb_bits_signed(int val, unsigned parameter)
 450 {
 451         unsigned bits, msbs, uval;
 452         unsigned k;
 453
 454         FLAC__ASSERT(parameter > 0);
 455
 456         /* fold signed to unsigned */
 457         if(val < 0)
 458                 uval = (unsigned)(((-(++val)) << 1) + 1);
 459         else
 460                 uval = (unsigned)(val << 1);
 461
 462         k = FLAC__bitmath_ilog2(parameter);
 463         if(parameter == 1u<<k) {
 464                 FLAC__ASSERT(k <= 30);
 465
 466                 msbs = uval >> k;
 467                 bits = 1 + k + msbs;
 468         }
 469         else {
 470                 unsigned q, r, d;
 471
 472                 d = (1 << (k+1)) - parameter;
 473                 q = uval / parameter;
 474                 r = uval - (q * parameter);
 475
 476                 bits = 1 + q + k;
 477                 if(r >= d)
 478                         bits++;
 479         }
 480         return bits;
 481 }
 482
 483 unsigned FLAC__bitwriter_golomb_bits_unsigned(unsigned uval, unsigned parameter)
 484 {
 485         unsigned bits, msbs;
 486         unsigned k;
 487
 488         FLAC__ASSERT(parameter > 0);
 489
 490         k = FLAC__bitmath_ilog2(parameter);
 491         if(parameter == 1u<<k) {
 492                 FLAC__ASSERT(k <= 30);
 493
 494                 msbs = uval >> k;
 495                 bits = 1 + k + msbs;
 496         }
 497         else {
 498                 unsigned q, r, d;
 499
 500                 d = (1 << (k+1)) - parameter;
 501                 q = uval / parameter;
 502                 r = uval - (q * parameter);
 503
 504                 bits = 1 + q + k;
 505                 if(r >= d)
 506                         bits++;
 507         }
 508         return bits;
 509 }
 510 #endif /* UNUSED */
 511
 512 FLAC__bool FLAC__bitwriter_write_rice_signed(FLAC__BitWriter *bw, FLAC__int32 val, unsigned parameter)
 513 {
 514         unsigned total_bits, interesting_bits, msbs;
 515         FLAC__uint32 uval, pattern;
 516
 517         FLAC__ASSERT(0 != bw);
 518         FLAC__ASSERT(0 != bw->buffer);
 519         FLAC__ASSERT(parameter < 8*sizeof(uval));
 520
 521         /* fold signed to unsigned; actual formula is: negative(v)? -2v-1 : 2v */
 522         uval = (val<<1) ^ (val>>31);
 523
 524         msbs = uval >> parameter;
 525         interesting_bits = 1 + parameter;
 526         total_bits = interesting_bits + msbs;
 527         pattern = 1 << parameter; /* the unary end bit */
 528         pattern |= (uval & ((1<<parameter)-1)); /* the binary LSBs */
 529
 530         if(total_bits <= 32)
 531                 return FLAC__bitwriter_write_raw_uint32(bw, pattern, total_bits);
 532         else
 533                 return
 534                         FLAC__bitwriter_write_zeroes(bw, msbs) && /* write the unary MSBs */
 535                         FLAC__bitwriter_write_raw_uint32(bw, pattern, interesting_bits); /* write the unary end bit and binary LSBs */
 536 }
 537
 538 FLAC__bool FLAC__bitwriter_write_rice_signed_block(FLAC__BitWriter *bw, const FLAC__int32 *vals, unsigned nvals, unsigned parameter)
 539 {
 540         const FLAC__uint32 mask1 = FLAC__WORD_ALL_ONES << parameter; /* we val|=mask1 to set the stop bit above it... */
 541         const FLAC__uint32 mask2 = FLAC__WORD_ALL_ONES >> (31-parameter); /* ...then mask off the bits above the stop bit with val&=mask2*/
 542         FLAC__uint32 uval;
 543         unsigned left;
 544         const unsigned lsbits = 1 + parameter;
 545         unsigned msbits;
 546
 547         FLAC__ASSERT(0 != bw);
 548         FLAC__ASSERT(0 != bw->buffer);
 549         FLAC__ASSERT(parameter < 8*sizeof(bwword)-1);
 550         /* WATCHOUT: code does not work with <32bit words; we can make things much faster with this assertion */
 551         FLAC__ASSERT(FLAC__BITS_PER_WORD >= 32);
 552
 553         while(nvals) {
 554                 /* fold signed to unsigned; actual formula is: negative(v)? -2v-1 : 2v */
 555         uval = (*vals<<1) ^ (*vals>>31);
 556
 557                 msbits = uval >> parameter;
 558
 559 #if 1 /* OPT: can remove this special case if it doesn't make up for the extra compare */
 560                 if(bw->bits + msbits + lsbits <= FLAC__BITS_PER_WORD) { /* i.e. if the whole thing fits in the current bwword */
 561                         bw->bits = bw->bits + msbits + lsbits;
 562                         uval |= mask1; /* set stop bit */
 563                         uval &= mask2; /* mask off unused top bits */
 564                         /* NOT: bw->accum <<= msbits + lsbits because msbits+lsbits could be 32, then the shift would be a NOP */
 565                         bw->accum <<= msbits;
 566                         bw->accum <<= lsbits;
 567                         bw->accum |= uval;
 568                         if(bw->bits == FLAC__BITS_PER_WORD) {
 569                                 bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum);
 570                                 bw->bits = 0;
 571                                 /* burying the capacity check down here means we have to grow the buffer a little if there are more vals to do */
 572                                 if(bw->capacity <= bw->words && nvals > 1 && !bitwriter_grow_(bw, 1)) {
 573                                         FLAC__ASSERT(bw->capacity == bw->words);
 574                                         return false;
 575                                 }
 576                         }
 577                 }
 578                 else {
 579 #elif 0 /*@@@@@@ OPT: try this version with MSVC6 to see if better, not much difference for gcc-4 */
 580                 if(bw->bits + msbits + lsbits < FLAC__BITS_PER_WORD) { /* i.e. if the whole thing fits in the current bwword */
 581                         bw->bits = bw->bits + msbits + lsbits;
 582                         uval |= mask1; /* set stop bit */
 583                         uval &= mask2; /* mask off unused top bits */
 584                         bw->accum <<= msbits + lsbits;
 585                         bw->accum |= uval;
 586                 }
 587                 else {
 588 #endif
 589                         /* slightly pessimistic size check but faster than "<= bw->words + (bw->bits+msbits+lsbits+FLAC__BITS_PER_WORD-1)/FLAC__BITS_PER_WORD" */
 590                         /* OPT: pessimism may cause flurry of false calls to grow_ which eat up all savings before it */
 591                         if(bw->capacity <= bw->words + bw->bits + msbits + 1/*lsbits always fit in 1 bwword*/ && !bitwriter_grow_(bw, msbits+lsbits))
 592                                 return false;
 593
 594                         if(msbits) {
 595                                 /* first part gets to word alignment */
 596                                 if(bw->bits) {
 597                                         left = FLAC__BITS_PER_WORD - bw->bits;
 598                                         if(msbits < left) {
 599                                                 bw->accum <<= msbits;
 600                                                 bw->bits += msbits;
 601                                                 goto break1;
 602                                         }
 603                                         else {
 604                                                 bw->accum <<= left;
 605                                                 msbits -= left;
 606                                                 bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum);
 607                                                 bw->bits = 0;
 608                                         }
 609                                 }
 610                                 /* do whole words */
 611                                 while(msbits >= FLAC__BITS_PER_WORD) {
 612                                         bw->buffer[bw->words++] = 0;
 613                                         msbits -= FLAC__BITS_PER_WORD;
 614                                 }
 615                                 /* do any leftovers */
 616                                 if(msbits > 0) {
 617                                         bw->accum = 0;
 618                                         bw->bits = msbits;
 619                                 }
 620                         }
 621 break1:
 622                         uval |= mask1; /* set stop bit */
 623                         uval &= mask2; /* mask off unused top bits */
 624
 625                         left = FLAC__BITS_PER_WORD - bw->bits;
 626                         if(lsbits < left) {
 627                                 bw->accum <<= lsbits;
 628                                 bw->accum |= uval;
 629                                 bw->bits += lsbits;
 630                         }
 631                         else {
 632                                 /* if bw->bits == 0, left==FLAC__BITS_PER_WORD which will always
 633                                  * be > lsbits (because of previous assertions) so it would have
 634                                  * triggered the (lsbits<left) case above.
 635                                  */
 636                                 FLAC__ASSERT(bw->bits);
 637                                 FLAC__ASSERT(left < FLAC__BITS_PER_WORD);
 638                                 bw->accum <<= left;
 639                                 bw->accum |= uval >> (bw->bits = lsbits - left);
 640                                 bw->buffer[bw->words++] = SWAP_BE_WORD_TO_HOST(bw->accum);
 641                                 bw->accum = uval;
 642                         }
 643 #if 1
 644                 }
 645 #endif
 646                 vals++;
 647                 nvals--;
 648         }
 649         return true;
 650 }
 651
 652 #if 0 /* UNUSED */
 653 FLAC__bool FLAC__bitwriter_write_golomb_signed(FLAC__BitWriter *bw, int val, unsigned parameter)
 654 {
 655         unsigned total_bits, msbs, uval;
 656         unsigned k;
 657
 658         FLAC__ASSERT(0 != bw);
 659         FLAC__ASSERT(0 != bw->buffer);
 660         FLAC__ASSERT(parameter > 0);
 661
 662         /* fold signed to unsigned */
 663         if(val < 0)
 664                 uval = (unsigned)(((-(++val)) << 1) + 1);
 665         else
 666                 uval = (unsigned)(val << 1);
 667
 668         k = FLAC__bitmath_ilog2(parameter);
 669         if(parameter == 1u<<k) {
 670                 unsigned pattern;
 671
 672                 FLAC__ASSERT(k <= 30);
 673
 674                 msbs = uval >> k;
 675                 total_bits = 1 + k + msbs;
 676                 pattern = 1 << k; /* the unary end bit */
 677                 pattern |= (uval & ((1u<<k)-1)); /* the binary LSBs */
 678
 679                 if(total_bits <= 32) {
 680                         if(!FLAC__bitwriter_write_raw_uint32(bw, pattern, total_bits))
 681                                 return false;
 682                 }
 683                 else {
 684                         /* write the unary MSBs */
 685                         if(!FLAC__bitwriter_write_zeroes(bw, msbs))
 686                                 return false;
 687                         /* write the unary end bit and binary LSBs */
 688                         if(!FLAC__bitwriter_write_raw_uint32(bw, pattern, k+1))
 689                                 return false;
 690                 }
 691         }
 692         else {
 693                 unsigned q, r, d;
 694
 695                 d = (1 << (k+1)) - parameter;
 696                 q = uval / parameter;
 697                 r = uval - (q * parameter);
 698                 /* write the unary MSBs */
 699                 if(!FLAC__bitwriter_write_zeroes(bw, q))
 700                         return false;
 701                 /* write the unary end bit */
 702                 if(!FLAC__bitwriter_write_raw_uint32(bw, 1, 1))
 703                         return false;
 704                 /* write the binary LSBs */
 705                 if(r >= d) {
 706                         if(!FLAC__bitwriter_write_raw_uint32(bw, r+d, k+1))
 707                                 return false;
 708                 }
 709                 else {
 710                         if(!FLAC__bitwriter_write_raw_uint32(bw, r, k))
 711                                 return false;
 712                 }
 713         }
 714         return true;
 715 }
 716
 717 FLAC__bool FLAC__bitwriter_write_golomb_unsigned(FLAC__BitWriter *bw, unsigned uval, unsigned parameter)
 718 {
 719         unsigned total_bits, msbs;
 720         unsigned k;
 721
 722         FLAC__ASSERT(0 != bw);
 723         FLAC__ASSERT(0 != bw->buffer);
 724         FLAC__ASSERT(parameter > 0);
 725
 726         k = FLAC__bitmath_ilog2(parameter);
 727         if(parameter == 1u<<k) {
 728                 unsigned pattern;
 729
 730                 FLAC__ASSERT(k <= 30);
 731
 732                 msbs = uval >> k;
 733                 total_bits = 1 + k + msbs;
 734                 pattern = 1 << k; /* the unary end bit */
 735                 pattern |= (uval & ((1u<<k)-1)); /* the binary LSBs */
 736
 737                 if(total_bits <= 32) {
 738                         if(!FLAC__bitwriter_write_raw_uint32(bw, pattern, total_bits))
 739                                 return false;
 740                 }
 741                 else {
 742                         /* write the unary MSBs */
 743                         if(!FLAC__bitwriter_write_zeroes(bw, msbs))
 744                                 return false;
 745                         /* write the unary end bit and binary LSBs */
 746                         if(!FLAC__bitwriter_write_raw_uint32(bw, pattern, k+1))
 747                                 return false;
 748                 }
 749         }
 750         else {
 751                 unsigned q, r, d;
 752
 753                 d = (1 << (k+1)) - parameter;
 754                 q = uval / parameter;
 755                 r = uval - (q * parameter);
 756                 /* write the unary MSBs */
 757                 if(!FLAC__bitwriter_write_zeroes(bw, q))
 758                         return false;
 759                 /* write the unary end bit */
 760                 if(!FLAC__bitwriter_write_raw_uint32(bw, 1, 1))
 761                         return false;
 762                 /* write the binary LSBs */
 763                 if(r >= d) {
 764                         if(!FLAC__bitwriter_write_raw_uint32(bw, r+d, k+1))
 765                                 return false;
 766                 }
 767                 else {
 768                         if(!FLAC__bitwriter_write_raw_uint32(bw, r, k))
 769                                 return false;
 770                 }
 771         }
 772         return true;
 773 }
 774 #endif /* UNUSED */
 775
 776 FLAC__bool FLAC__bitwriter_write_utf8_uint32(FLAC__BitWriter *bw, FLAC__uint32 val)
 777 {
 778         FLAC__bool ok = 1;
 779
 780         FLAC__ASSERT(0 != bw);
 781         FLAC__ASSERT(0 != bw->buffer);
 782
 783         FLAC__ASSERT(!(val & 0x80000000)); /* this version only handles 31 bits */
 784
 785         if(val < 0x80) {
 786                 return FLAC__bitwriter_write_raw_uint32(bw, val, 8);
 787         }
 788         else if(val < 0x800) {
 789                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xC0 | (val>>6), 8);
 790                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (val&0x3F), 8);
 791         }
 792         else if(val < 0x10000) {
 793                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xE0 | (val>>12), 8);
 794                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>6)&0x3F), 8);
 795                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (val&0x3F), 8);
 796         }
 797         else if(val < 0x200000) {
 798                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xF0 | (val>>18), 8);
 799                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>12)&0x3F), 8);
 800                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>6)&0x3F), 8);
 801                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (val&0x3F), 8);
 802         }
 803         else if(val < 0x4000000) {
 804                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xF8 | (val>>24), 8);
 805                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>18)&0x3F), 8);
 806                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>12)&0x3F), 8);
 807                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>6)&0x3F), 8);
 808                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (val&0x3F), 8);
 809         }
 810         else {
 811                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xFC | (val>>30), 8);
 812                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>24)&0x3F), 8);
 813                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>18)&0x3F), 8);
 814                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>12)&0x3F), 8);
 815                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | ((val>>6)&0x3F), 8);
 816                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (val&0x3F), 8);
 817         }
 818
 819         return ok;
 820 }
 821
 822 FLAC__bool FLAC__bitwriter_write_utf8_uint64(FLAC__BitWriter *bw, FLAC__uint64 val)
 823 {
 824         FLAC__bool ok = 1;
 825
 826         FLAC__ASSERT(0 != bw);
 827         FLAC__ASSERT(0 != bw->buffer);
 828
 829         FLAC__ASSERT(!(val & FLAC__U64L(0xFFFFFFF000000000))); /* this version only handles 36 bits */
 830
 831         if(val < 0x80) {
 832                 return FLAC__bitwriter_write_raw_uint32(bw, (FLAC__uint32)val, 8);
 833         }
 834         else if(val < 0x800) {
 835                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xC0 | (FLAC__uint32)(val>>6), 8);
 836                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
 837         }
 838         else if(val < 0x10000) {
 839                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xE0 | (FLAC__uint32)(val>>12), 8);
 840                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
 841                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
 842         }
 843         else if(val < 0x200000) {
 844                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xF0 | (FLAC__uint32)(val>>18), 8);
 845                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>12)&0x3F), 8);
 846                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
 847                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
 848         }
 849         else if(val < 0x4000000) {
 850                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xF8 | (FLAC__uint32)(val>>24), 8);
 851                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>18)&0x3F), 8);
 852                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>12)&0x3F), 8);
 853                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
 854                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
 855         }
 856         else if(val < 0x80000000) {
 857                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xFC | (FLAC__uint32)(val>>30), 8);
 858                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>24)&0x3F), 8);
 859                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>18)&0x3F), 8);
 860                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>12)&0x3F), 8);
 861                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
 862                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
 863         }
 864         else {
 865                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0xFE, 8);
 866                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>30)&0x3F), 8);
 867                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>24)&0x3F), 8);
 868                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>18)&0x3F), 8);
 869                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>12)&0x3F), 8);
 870                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)((val>>6)&0x3F), 8);
 871                 ok &= FLAC__bitwriter_write_raw_uint32(bw, 0x80 | (FLAC__uint32)(val&0x3F), 8);
 872         }
 873
 874         return ok;
 875 }
 876
 877 FLAC__bool FLAC__bitwriter_zero_pad_to_byte_boundary(FLAC__BitWriter *bw)
 878 {
 879         /* 0-pad to byte boundary */
 880         if(bw->bits & 7u)
 881                 return FLAC__bitwriter_write_zeroes(bw, 8 - (bw->bits & 7u));
 882         else
 883                 return true;
 884 }