src/libFLAC/seekable_stream_decoder.c

   1 /* libFLAC - Free Lossless Audio Codec library
   2  * Copyright (C) 2000,2001,2002  Josh Coalson
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA  02111-1307, USA.
  18  */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h> /* for malloc() */
  22 #include <string.h> /* for memcpy()/memcmp() */
  23 #include "FLAC/assert.h"
  24 #include "protected/seekable_stream_decoder.h"
  25 #include "protected/stream_decoder.h"
  26 #include "private/md5.h"
  27
  28 /***********************************************************************
  29  *
  30  * Private class method prototypes
  31  *
  32  ***********************************************************************/
  33
  34 static void set_defaults_(FLAC__SeekableStreamDecoder *decoder);
  35 static FLAC__StreamDecoderReadStatus read_callback_(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data);
  36 static FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data);
  37 static void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data);
  38 static void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data);
  39 static FLAC__bool seek_to_absolute_sample_(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample);
  40
  41 /***********************************************************************
  42  *
  43  * Private class data
  44  *
  45  ***********************************************************************/
  46
  47 typedef struct FLAC__SeekableStreamDecoderPrivate {
  48         FLAC__SeekableStreamDecoderReadCallback read_callback;
  49         FLAC__SeekableStreamDecoderSeekCallback seek_callback;
  50         FLAC__SeekableStreamDecoderTellCallback tell_callback;
  51         FLAC__SeekableStreamDecoderLengthCallback length_callback;
  52         FLAC__SeekableStreamDecoderEofCallback eof_callback;
  53         FLAC__SeekableStreamDecoderWriteCallback write_callback;
  54         FLAC__SeekableStreamDecoderMetadataCallback metadata_callback;
  55         FLAC__SeekableStreamDecoderErrorCallback error_callback;
  56         void *client_data;
  57         FLAC__StreamDecoder *stream_decoder;
  58         FLAC__bool do_md5_checking; /* initially gets protected_->md5_checking but is turned off after a seek */
  59         struct MD5Context md5context;
  60         FLAC__byte stored_md5sum[16]; /* this is what is stored in the metadata */
  61         FLAC__byte computed_md5sum[16]; /* this is the sum we computed from the decoded data */
  62         /* the rest of these are only used for seeking: */
  63         FLAC__StreamMetadata_StreamInfo stream_info; /* we keep this around so we can figure out how to seek quickly */
  64         const FLAC__StreamMetadata_SeekTable *seek_table; /* we hold a pointer to the stream decoder's seek table for the same reason */
  65         /* Since we always want to see the STREAMINFO and SEEK_TABLE blocks at this level, we need some extra flags to keep track of whether they should be passed on up through the metadata_callback */
  66         FLAC__bool ignore_stream_info_block;
  67         FLAC__bool ignore_seek_table_block;
  68         FLAC__Frame last_frame; /* holds the info of the last frame we seeked to */
  69         FLAC__uint64 target_sample;
  70 } FLAC__SeekableStreamDecoderPrivate;
  71
  72 /***********************************************************************
  73  *
  74  * Public static class data
  75  *
  76  ***********************************************************************/
  77
  78 const char * const FLAC__SeekableStreamDecoderStateString[] = {
  79         "FLAC__SEEKABLE_STREAM_DECODER_OK",
  80         "FLAC__SEEKABLE_STREAM_DECODER_SEEKING",
  81         "FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM",
  82         "FLAC__SEEKABLE_STREAM_DECODER_MEMORY_ALLOCATION_ERROR",
  83         "FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR",
  84         "FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR",
  85         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR",
  86         "FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED",
  87         "FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK",
  88         "FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED"
  89 };
  90
  91 const char * const FLAC__SeekableStreamDecoderReadStatusString[] = {
  92         "FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_OK",
  93         "FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_ERROR"
  94 };
  95
  96 const char * const FLAC__SeekableStreamDecoderSeekStatusString[] = {
  97         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK",
  98         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_ERROR"
  99 };
 100
 101 const char * const FLAC__SeekableStreamDecoderTellStatusString[] = {
 102         "FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK",
 103         "FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_ERROR"
 104 };
 105
 106 const char * const FLAC__SeekableStreamDecoderLengthStatusString[] = {
 107         "FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK",
 108         "FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_ERROR"
 109 };
 110
 111
 112 /***********************************************************************
 113  *
 114  * Class constructor/destructor
 115  *
 116  ***********************************************************************/
 117
 118 FLAC__SeekableStreamDecoder *FLAC__seekable_stream_decoder_new()
 119 {
 120         FLAC__SeekableStreamDecoder *decoder;
 121
 122         FLAC__ASSERT(sizeof(int) >= 4); /* we want to die right away if this is not true */
 123
 124         decoder = (FLAC__SeekableStreamDecoder*)malloc(sizeof(FLAC__SeekableStreamDecoder));
 125         if(decoder == 0) {
 126                 return 0;
 127         }
 128         decoder->protected_ = (FLAC__SeekableStreamDecoderProtected*)malloc(sizeof(FLAC__SeekableStreamDecoderProtected));
 129         if(decoder->protected_ == 0) {
 130                 free(decoder);
 131                 return 0;
 132         }
 133         decoder->private_ = (FLAC__SeekableStreamDecoderPrivate*)malloc(sizeof(FLAC__SeekableStreamDecoderPrivate));
 134         if(decoder->private_ == 0) {
 135                 free(decoder->protected_);
 136                 free(decoder);
 137                 return 0;
 138         }
 139
 140         decoder->private_->stream_decoder = FLAC__stream_decoder_new();
 141
 142         if(0 == decoder->private_->stream_decoder) {
 143                 free(decoder->private_);
 144                 free(decoder->protected_);
 145                 free(decoder);
 146                 return 0;
 147         }
 148
 149         set_defaults_(decoder);
 150
 151         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
 152
 153         return decoder;
 154 }
 155
 156 void FLAC__seekable_stream_decoder_delete(FLAC__SeekableStreamDecoder *decoder)
 157 {
 158         FLAC__ASSERT(0 != decoder);
 159         FLAC__ASSERT(0 != decoder->protected_);
 160         FLAC__ASSERT(0 != decoder->private_);
 161         FLAC__ASSERT(0 != decoder->private_->stream_decoder);
 162
 163         (void)FLAC__seekable_stream_decoder_finish(decoder);
 164
 165         FLAC__stream_decoder_delete(decoder->private_->stream_decoder);
 166
 167         free(decoder->private_);
 168         free(decoder->protected_);
 169         free(decoder);
 170 }
 171
 172 /***********************************************************************
 173  *
 174  * Public class methods
 175  *
 176  ***********************************************************************/
 177
 178 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_init(FLAC__SeekableStreamDecoder *decoder)
 179 {
 180         FLAC__ASSERT(0 != decoder);
 181
 182         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 183                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED;
 184
 185         if(0 == decoder->private_->read_callback || 0 == decoder->private_->seek_callback || 0 == decoder->private_->tell_callback || 0 == decoder->private_->length_callback || 0 == decoder->private_->eof_callback)
 186                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
 187
 188         if(0 == decoder->private_->write_callback || 0 == decoder->private_->metadata_callback || 0 == decoder->private_->error_callback)
 189                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
 190
 191         decoder->private_->seek_table = 0;
 192
 193         decoder->private_->do_md5_checking = decoder->protected_->md5_checking;
 194
 195         /* We initialize the MD5Context even though we may never use it.  This is
 196          * because md5 checking may be turned on to start and then turned off if a
 197          * seek occurs.  So we always init the context here and finalize it in
 198          * FLAC__seekable_stream_decoder_finish() to make sure things are always
 199          * cleaned up properly.
 200          */
 201         MD5Init(&decoder->private_->md5context);
 202
 203         FLAC__stream_decoder_set_read_callback(decoder->private_->stream_decoder, read_callback_);
 204         FLAC__stream_decoder_set_write_callback(decoder->private_->stream_decoder, write_callback_);
 205         FLAC__stream_decoder_set_metadata_callback(decoder->private_->stream_decoder, metadata_callback_);
 206         FLAC__stream_decoder_set_error_callback(decoder->private_->stream_decoder, error_callback_);
 207         FLAC__stream_decoder_set_client_data(decoder->private_->stream_decoder, decoder);
 208
 209         /* We always want to see these blocks.  Whether or not we pass them up
 210          * through the metadata callback will be determined by flags set in our
 211          * implementation of ..._set_metadata_respond/ignore...()
 212          */
 213         FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, FLAC__METADATA_TYPE_STREAMINFO);
 214         FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, FLAC__METADATA_TYPE_SEEKTABLE);
 215
 216         if(FLAC__stream_decoder_init(decoder->private_->stream_decoder) != FLAC__STREAM_DECODER_SEARCH_FOR_METADATA)
 217                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 218
 219         return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 220 }
 221
 222 FLAC__bool FLAC__seekable_stream_decoder_finish(FLAC__SeekableStreamDecoder *decoder)
 223 {
 224         FLAC__bool md5_failed = false;
 225
 226         FLAC__ASSERT(0 != decoder);
 227         FLAC__ASSERT(0 != decoder->private_);
 228         FLAC__ASSERT(0 != decoder->protected_);
 229
 230         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 231                 return true;
 232
 233         FLAC__ASSERT(0 != decoder->private_->stream_decoder);
 234
 235         /* see the comment in FLAC__seekable_stream_decoder_init() as to why we
 236          * always call MD5Final()
 237          */
 238         MD5Final(decoder->private_->computed_md5sum, &decoder->private_->md5context);
 239
 240         FLAC__stream_decoder_finish(decoder->private_->stream_decoder);
 241
 242         if(decoder->private_->do_md5_checking) {
 243                 if(memcmp(decoder->private_->stored_md5sum, decoder->private_->computed_md5sum, 16))
 244                         md5_failed = true;
 245         }
 246
 247         set_defaults_(decoder);
 248
 249         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
 250
 251         return !md5_failed;
 252 }
 253
 254 FLAC__bool FLAC__seekable_stream_decoder_set_md5_checking(FLAC__SeekableStreamDecoder *decoder, FLAC__bool value)
 255 {
 256         FLAC__ASSERT(0 != decoder);
 257         FLAC__ASSERT(0 != decoder->protected_);
 258         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 259                 return false;
 260         decoder->protected_->md5_checking = value;
 261         return true;
 262 }
 263
 264 FLAC__bool FLAC__seekable_stream_decoder_set_read_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderReadCallback value)
 265 {
 266         FLAC__ASSERT(0 != decoder);
 267         FLAC__ASSERT(0 != decoder->private_);
 268         FLAC__ASSERT(0 != decoder->protected_);
 269         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 270                 return false;
 271         decoder->private_->read_callback = value;
 272         return true;
 273 }
 274
 275 FLAC__bool FLAC__seekable_stream_decoder_set_seek_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderSeekCallback value)
 276 {
 277         FLAC__ASSERT(0 != decoder);
 278         FLAC__ASSERT(0 != decoder->private_);
 279         FLAC__ASSERT(0 != decoder->protected_);
 280         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 281                 return false;
 282         decoder->private_->seek_callback = value;
 283         return true;
 284 }
 285
 286 FLAC__bool FLAC__seekable_stream_decoder_set_tell_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderTellCallback value)
 287 {
 288         FLAC__ASSERT(0 != decoder);
 289         FLAC__ASSERT(0 != decoder->private_);
 290         FLAC__ASSERT(0 != decoder->protected_);
 291         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 292                 return false;
 293         decoder->private_->tell_callback = value;
 294         return true;
 295 }
 296
 297 FLAC__bool FLAC__seekable_stream_decoder_set_length_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderLengthCallback value)
 298 {
 299         FLAC__ASSERT(0 != decoder);
 300         FLAC__ASSERT(0 != decoder->private_);
 301         FLAC__ASSERT(0 != decoder->protected_);
 302         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 303                 return false;
 304         decoder->private_->length_callback = value;
 305         return true;
 306 }
 307
 308 FLAC__bool FLAC__seekable_stream_decoder_set_eof_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderEofCallback value)
 309 {
 310         FLAC__ASSERT(0 != decoder);
 311         FLAC__ASSERT(0 != decoder->private_);
 312         FLAC__ASSERT(0 != decoder->protected_);
 313         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 314                 return false;
 315         decoder->private_->eof_callback = value;
 316         return true;
 317 }
 318
 319 FLAC__bool FLAC__seekable_stream_decoder_set_write_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderWriteCallback value)
 320 {
 321         FLAC__ASSERT(0 != decoder);
 322         FLAC__ASSERT(0 != decoder->private_);
 323         FLAC__ASSERT(0 != decoder->protected_);
 324         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 325                 return false;
 326         decoder->private_->write_callback = value;
 327         return true;
 328 }
 329
 330 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderMetadataCallback value)
 331 {
 332         FLAC__ASSERT(0 != decoder);
 333         FLAC__ASSERT(0 != decoder->private_);
 334         FLAC__ASSERT(0 != decoder->protected_);
 335         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 336                 return false;
 337         decoder->private_->metadata_callback = value;
 338         return true;
 339 }
 340
 341 FLAC__bool FLAC__seekable_stream_decoder_set_error_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderErrorCallback value)
 342 {
 343         FLAC__ASSERT(0 != decoder);
 344         FLAC__ASSERT(0 != decoder->private_);
 345         FLAC__ASSERT(0 != decoder->protected_);
 346         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 347                 return false;
 348         decoder->private_->error_callback = value;
 349         return true;
 350 }
 351
 352 FLAC__bool FLAC__seekable_stream_decoder_set_client_data(FLAC__SeekableStreamDecoder *decoder, void *value)
 353 {
 354         FLAC__ASSERT(0 != decoder);
 355         FLAC__ASSERT(0 != decoder->private_);
 356         FLAC__ASSERT(0 != decoder->protected_);
 357         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 358                 return false;
 359         decoder->private_->client_data = value;
 360         return true;
 361 }
 362
 363 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond(FLAC__SeekableStreamDecoder *decoder, FLAC__MetadataType type)
 364 {
 365         FLAC__ASSERT(0 != decoder);
 366         FLAC__ASSERT(0 != decoder->private_);
 367         FLAC__ASSERT(0 != decoder->protected_);
 368         FLAC__ASSERT(0 != decoder->private_->stream_decoder);
 369         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 370                 return false;
 371         if(type == FLAC__METADATA_TYPE_STREAMINFO)
 372                 decoder->private_->ignore_stream_info_block = false;
 373         else if(type == FLAC__METADATA_TYPE_SEEKTABLE)
 374                 decoder->private_->ignore_seek_table_block = false;
 375         return FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, type);
 376 }
 377
 378 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond_application(FLAC__SeekableStreamDecoder *decoder, const FLAC__byte id[4])
 379 {
 380         FLAC__ASSERT(0 != decoder);
 381         FLAC__ASSERT(0 != decoder->private_);
 382         FLAC__ASSERT(0 != decoder->protected_);
 383         FLAC__ASSERT(0 != decoder->private_->stream_decoder);
 384         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 385                 return false;
 386         return FLAC__stream_decoder_set_metadata_respond_application(decoder->private_->stream_decoder, id);
 387 }
 388
 389 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond_all(FLAC__SeekableStreamDecoder *decoder)
 390 {
 391         FLAC__ASSERT(0 != decoder);
 392         FLAC__ASSERT(0 != decoder->private_);
 393         FLAC__ASSERT(0 != decoder->protected_);
 394         FLAC__ASSERT(0 != decoder->private_->stream_decoder);
 395         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 396                 return false;
 397         decoder->private_->ignore_stream_info_block = false;
 398         decoder->private_->ignore_seek_table_block = false;
 399         return FLAC__stream_decoder_set_metadata_respond_all(decoder->private_->stream_decoder);
 400 }
 401
 402 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore(FLAC__SeekableStreamDecoder *decoder, FLAC__MetadataType type)
 403 {
 404         FLAC__ASSERT(0 != decoder);
 405         FLAC__ASSERT(0 != decoder->private_);
 406         FLAC__ASSERT(0 != decoder->protected_);
 407         FLAC__ASSERT(0 != decoder->private_->stream_decoder);
 408         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 409                 return false;
 410         if(type == FLAC__METADATA_TYPE_STREAMINFO)
 411                 decoder->private_->ignore_stream_info_block = true;
 412         else if(type == FLAC__METADATA_TYPE_SEEKTABLE)
 413                 decoder->private_->ignore_seek_table_block = true;
 414         return FLAC__stream_decoder_set_metadata_ignore(decoder->private_->stream_decoder, type);
 415 }
 416
 417 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore_application(FLAC__SeekableStreamDecoder *decoder, const FLAC__byte id[4])
 418 {
 419         FLAC__ASSERT(0 != decoder);
 420         FLAC__ASSERT(0 != decoder->private_);
 421         FLAC__ASSERT(0 != decoder->protected_);
 422         FLAC__ASSERT(0 != decoder->private_->stream_decoder);
 423         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 424                 return false;
 425         return FLAC__stream_decoder_set_metadata_ignore_application(decoder->private_->stream_decoder, id);
 426 }
 427
 428 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore_all(FLAC__SeekableStreamDecoder *decoder)
 429 {
 430         FLAC__ASSERT(0 != decoder);
 431         FLAC__ASSERT(0 != decoder->private_);
 432         FLAC__ASSERT(0 != decoder->protected_);
 433         FLAC__ASSERT(0 != decoder->private_->stream_decoder);
 434         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 435                 return false;
 436         decoder->private_->ignore_stream_info_block = true;
 437         decoder->private_->ignore_seek_table_block = true;
 438         return FLAC__stream_decoder_set_metadata_ignore_all(decoder->private_->stream_decoder);
 439 }
 440
 441 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_get_state(const FLAC__SeekableStreamDecoder *decoder)
 442 {
 443         FLAC__ASSERT(0 != decoder);
 444         FLAC__ASSERT(0 != decoder->protected_);
 445         return decoder->protected_->state;
 446 }
 447
 448 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_get_stream_decoder_state(const FLAC__SeekableStreamDecoder *decoder)
 449 {
 450         FLAC__ASSERT(0 != decoder);
 451         FLAC__ASSERT(0 != decoder->private_);
 452         return FLAC__stream_decoder_get_state(decoder->private_->stream_decoder);
 453 }
 454
 455 FLAC__bool FLAC__seekable_stream_decoder_get_md5_checking(const FLAC__SeekableStreamDecoder *decoder)
 456 {
 457         FLAC__ASSERT(0 != decoder);
 458         FLAC__ASSERT(0 != decoder->protected_);
 459         return decoder->protected_->md5_checking;
 460 }
 461
 462 unsigned FLAC__seekable_stream_decoder_get_channels(const FLAC__SeekableStreamDecoder *decoder)
 463 {
 464         FLAC__ASSERT(0 != decoder);
 465         FLAC__ASSERT(0 != decoder->private_);
 466         return FLAC__stream_decoder_get_channels(decoder->private_->stream_decoder);
 467 }
 468
 469 FLAC__ChannelAssignment FLAC__seekable_stream_decoder_get_channel_assignment(const FLAC__SeekableStreamDecoder *decoder)
 470 {
 471         FLAC__ASSERT(0 != decoder);
 472         FLAC__ASSERT(0 != decoder->private_);
 473         return FLAC__stream_decoder_get_channel_assignment(decoder->private_->stream_decoder);
 474 }
 475
 476 unsigned FLAC__seekable_stream_decoder_get_bits_per_sample(const FLAC__SeekableStreamDecoder *decoder)
 477 {
 478         FLAC__ASSERT(0 != decoder);
 479         FLAC__ASSERT(0 != decoder->private_);
 480         return FLAC__stream_decoder_get_bits_per_sample(decoder->private_->stream_decoder);
 481 }
 482
 483 unsigned FLAC__seekable_stream_decoder_get_sample_rate(const FLAC__SeekableStreamDecoder *decoder)
 484 {
 485         FLAC__ASSERT(0 != decoder);
 486         FLAC__ASSERT(0 != decoder->private_);
 487         return FLAC__stream_decoder_get_sample_rate(decoder->private_->stream_decoder);
 488 }
 489
 490 unsigned FLAC__seekable_stream_decoder_get_blocksize(const FLAC__SeekableStreamDecoder *decoder)
 491 {
 492         FLAC__ASSERT(0 != decoder);
 493         FLAC__ASSERT(0 != decoder->private_);
 494         return FLAC__stream_decoder_get_blocksize(decoder->private_->stream_decoder);
 495 }
 496
 497 FLAC__bool FLAC__seekable_stream_decoder_flush(FLAC__SeekableStreamDecoder *decoder)
 498 {
 499         FLAC__ASSERT(0 != decoder);
 500         FLAC__ASSERT(0 != decoder->private_);
 501         FLAC__ASSERT(0 != decoder->protected_);
 502
 503         decoder->private_->do_md5_checking = false;
 504
 505         if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
 506                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 507                 return false;
 508         }
 509
 510         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 511
 512         return true;
 513 }
 514
 515 FLAC__bool FLAC__seekable_stream_decoder_reset(FLAC__SeekableStreamDecoder *decoder)
 516 {
 517         FLAC__ASSERT(0 != decoder);
 518         FLAC__ASSERT(0 != decoder->private_);
 519         FLAC__ASSERT(0 != decoder->protected_);
 520
 521         if(!FLAC__seekable_stream_decoder_flush(decoder)) {
 522                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 523                 return false;
 524         }
 525
 526         if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
 527                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 528                 return false;
 529         }
 530
 531         decoder->private_->seek_table = 0;
 532
 533         decoder->private_->do_md5_checking = decoder->protected_->md5_checking;
 534
 535         /* We initialize the MD5Context even though we may never use it.  This is
 536          * because md5 checking may be turned on to start and then turned off if a
 537          * seek occurs.  So we always init the context here and finalize it in
 538          * FLAC__seekable_stream_decoder_finish() to make sure things are always
 539          * cleaned up properly.
 540          */
 541         MD5Init(&decoder->private_->md5context);
 542
 543         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 544
 545         return true;
 546 }
 547
 548 FLAC__bool FLAC__seekable_stream_decoder_process_single(FLAC__SeekableStreamDecoder *decoder)
 549 {
 550         FLAC__bool ret;
 551         FLAC__ASSERT(0 != decoder);
 552
 553         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 554                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 555
 556         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 557                 return true;
 558
 559         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 560
 561         ret = FLAC__stream_decoder_process_single(decoder->private_->stream_decoder);
 562         if(!ret)
 563                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 564
 565         return ret;
 566 }
 567
 568 FLAC__bool FLAC__seekable_stream_decoder_process_until_end_of_metadata(FLAC__SeekableStreamDecoder *decoder)
 569 {
 570         FLAC__bool ret;
 571         FLAC__ASSERT(0 != decoder);
 572
 573         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 574                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 575
 576         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 577                 return true;
 578
 579         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 580
 581         ret = FLAC__stream_decoder_process_until_end_of_metadata(decoder->private_->stream_decoder);
 582         if(!ret)
 583                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 584
 585         return ret;
 586 }
 587
 588 FLAC__bool FLAC__seekable_stream_decoder_process_until_end_of_stream(FLAC__SeekableStreamDecoder *decoder)
 589 {
 590         FLAC__bool ret;
 591         FLAC__ASSERT(0 != decoder);
 592
 593         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 594                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 595
 596         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 597                 return true;
 598
 599         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 600
 601         ret = FLAC__stream_decoder_process_until_end_of_stream(decoder->private_->stream_decoder);
 602         if(!ret)
 603                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 604
 605         return ret;
 606 }
 607
 608 FLAC__bool FLAC__seekable_stream_decoder_seek_absolute(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 sample)
 609 {
 610         FLAC__uint64 length;
 611
 612         FLAC__ASSERT(0 != decoder);
 613         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK || decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM);
 614
 615         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEKING;
 616
 617         /* turn off md5 checking if a seek is attempted */
 618         decoder->private_->do_md5_checking = false;
 619
 620         if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
 621                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 622                 return false;
 623         }
 624         /* get the file length */
 625         if(decoder->private_->length_callback(decoder, &length, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK) {
 626                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 627                 return false;
 628         }
 629         /* rewind */
 630         if(decoder->private_->seek_callback(decoder, 0, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
 631                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 632                 return false;
 633         }
 634         if(!FLAC__stream_decoder_process_until_end_of_metadata(decoder->private_->stream_decoder)) {
 635                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 636                 return false;
 637         }
 638         if(decoder->private_->stream_info.total_samples > 0 && sample > decoder->private_->stream_info.total_samples) {
 639                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 640                 return false;
 641         }
 642
 643         return seek_to_absolute_sample_(decoder, length, sample);
 644 }
 645
 646 /***********************************************************************
 647  *
 648  * Private class methods
 649  *
 650  ***********************************************************************/
 651
 652 void set_defaults_(FLAC__SeekableStreamDecoder *decoder)
 653 {
 654         decoder->private_->read_callback = 0;
 655         decoder->private_->seek_callback = 0;
 656         decoder->private_->tell_callback = 0;
 657         decoder->private_->length_callback = 0;
 658         decoder->private_->eof_callback = 0;
 659         decoder->private_->write_callback = 0;
 660         decoder->private_->metadata_callback = 0;
 661         decoder->private_->error_callback = 0;
 662         decoder->private_->client_data = 0;
 663         /* WATCHOUT: these should match the default behavior of FLAC__StreamDecoder */
 664         decoder->private_->ignore_stream_info_block = false;
 665         decoder->private_->ignore_seek_table_block = true;
 666
 667         decoder->protected_->md5_checking = false;
 668 }
 669
 670 FLAC__StreamDecoderReadStatus read_callback_(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data)
 671 {
 672         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 673         (void)decoder;
 674         if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
 675                 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 676                 return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 677         }
 678         else if(*bytes > 0) {
 679                 unsigned bytes_read = *bytes;
 680                 if(seekable_stream_decoder->private_->read_callback(seekable_stream_decoder, buffer, &bytes_read, seekable_stream_decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_OK) {
 681                         seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR;
 682                         return FLAC__STREAM_DECODER_READ_STATUS_ABORT;
 683                 }
 684                 if(bytes_read == 0) {
 685                         if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
 686                                 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 687                                 return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 688                         }
 689                         else
 690                                 return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
 691                 }
 692                 else {
 693                         *bytes = bytes_read;
 694                         return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
 695                 }
 696         }
 697         else
 698                 return FLAC__STREAM_DECODER_READ_STATUS_ABORT; /* abort to avoid a deadlock */
 699 }
 700
 701 FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 * const buffer[], void *client_data)
 702 {
 703         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 704         (void)decoder;
 705
 706         if(seekable_stream_decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 707                 FLAC__uint64 this_frame_sample = frame->header.number.sample_number;
 708                 FLAC__uint64 next_frame_sample = this_frame_sample + (FLAC__uint64)frame->header.blocksize;
 709                 FLAC__uint64 target_sample = seekable_stream_decoder->private_->target_sample;
 710
 711                 FLAC__ASSERT(frame->header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
 712
 713                 seekable_stream_decoder->private_->last_frame = *frame; /* save the frame */
 714                 if(this_frame_sample <= target_sample && target_sample < next_frame_sample) { /* we hit our target frame */
 715                         unsigned delta = (unsigned)(target_sample - this_frame_sample);
 716                         /* kick out of seek mode */
 717                         seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 718                         /* shift out the samples before target_sample */
 719                         if(delta > 0) {
 720                                 unsigned channel;
 721                                 const FLAC__int32 *newbuffer[FLAC__MAX_CHANNELS];
 722                                 for(channel = 0; channel < frame->header.channels; channel++)
 723                                         newbuffer[channel] = buffer[channel] + delta;
 724                                 seekable_stream_decoder->private_->last_frame.header.blocksize -= delta;
 725                                 seekable_stream_decoder->private_->last_frame.header.number.sample_number += (FLAC__uint64)delta;
 726                                 /* write the relevant samples */
 727                                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, &seekable_stream_decoder->private_->last_frame, newbuffer, seekable_stream_decoder->private_->client_data);
 728                         }
 729                         else {
 730                                 /* write the relevant samples */
 731                                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
 732                         }
 733                 }
 734                 else {
 735                         return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
 736                 }
 737         }
 738         else {
 739                 if(seekable_stream_decoder->private_->do_md5_checking) {
 740                         if(!FLAC__MD5Accumulate(&seekable_stream_decoder->private_->md5context, buffer, frame->header.channels, frame->header.blocksize, (frame->header.bits_per_sample+7) / 8))
 741                                 return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
 742                 }
 743                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
 744         }
 745 }
 746
 747 void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
 748 {
 749         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 750         (void)decoder;
 751
 752         if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
 753                 seekable_stream_decoder->private_->stream_info = metadata->data.stream_info;
 754                 /* save the MD5 signature for comparison later */
 755                 memcpy(seekable_stream_decoder->private_->stored_md5sum, metadata->data.stream_info.md5sum, 16);
 756                 if(0 == memcmp(seekable_stream_decoder->private_->stored_md5sum, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16))
 757                         seekable_stream_decoder->private_->do_md5_checking = false;
 758         }
 759         else if(metadata->type == FLAC__METADATA_TYPE_SEEKTABLE) {
 760                 seekable_stream_decoder->private_->seek_table = &metadata->data.seek_table;
 761         }
 762
 763         if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 764                 FLAC__bool ignore_block = false;
 765                 if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO && seekable_stream_decoder->private_->ignore_stream_info_block)
 766                         ignore_block = true;
 767                 else if(metadata->type == FLAC__METADATA_TYPE_SEEKTABLE && seekable_stream_decoder->private_->ignore_seek_table_block)
 768                         ignore_block = true;
 769                 if(!ignore_block)
 770                         seekable_stream_decoder->private_->metadata_callback(seekable_stream_decoder, metadata, seekable_stream_decoder->private_->client_data);
 771         }
 772 }
 773
 774 void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
 775 {
 776         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 777         (void)decoder;
 778
 779         if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING)
 780                 seekable_stream_decoder->private_->error_callback(seekable_stream_decoder, status, seekable_stream_decoder->private_->client_data);
 781 }
 782
 783 FLAC__bool seek_to_absolute_sample_(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample)
 784 {
 785         FLAC__uint64 first_frame_offset, lower_bound, upper_bound;
 786         FLAC__int64 pos = -1, last_pos = -1;
 787         int i, lower_seek_point = -1, upper_seek_point = -1;
 788         unsigned approx_bytes_per_frame;
 789         FLAC__uint64 last_frame_sample = 0xffffffffffffffff;
 790         FLAC__bool needs_seek;
 791         const FLAC__uint64 total_samples = decoder->private_->stream_info.total_samples;
 792         const unsigned min_blocksize = decoder->private_->stream_info.min_blocksize;
 793         const unsigned max_blocksize = decoder->private_->stream_info.max_blocksize;
 794         const unsigned max_framesize = decoder->private_->stream_info.max_framesize;
 795         const unsigned channels = FLAC__seekable_stream_decoder_get_channels(decoder);
 796         const unsigned bps = FLAC__seekable_stream_decoder_get_bits_per_sample(decoder);
 797
 798         /* we are just guessing here, but we want to guess high, not low */
 799         if(max_framesize > 0) {
 800                 approx_bytes_per_frame = max_framesize;
 801         }
 802         /*
 803          * Check if it's a known fixed-blocksize stream.  Note that though
 804          * the spec doesn't allow zeroes in the STREAMINFO block, we may
 805          * never get a STREAMINFO block when decoding so the value of
 806          * min_blocksize might be zero.
 807          */
 808         else if(min_blocksize == max_blocksize && min_blocksize > 0) {
 809                 /* note there are no () around 'bps/8' to keep precision up since it's an integer calulation */
 810                 approx_bytes_per_frame = min_blocksize * channels * bps/8 + 64;
 811         }
 812         else
 813                 approx_bytes_per_frame = 4608 * channels * bps/8 + 64;
 814
 815         /*
 816          * The stream position is currently at the first frame plus any read
 817          * ahead data, so first we get the stream position, then subtract
 818          * uncomsumed bytes to get the position of the first frame in the
 819          * stream.
 820          */
 821         if(decoder->private_->tell_callback(decoder, &first_frame_offset, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 822                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 823                 return false;
 824         }
 825         FLAC__ASSERT(first_frame_offset >= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder));
 826         first_frame_offset -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
 827
 828         /*
 829          * First, we set an upper and lower bound on where in the
 830          * stream we will search.  For now we assume the worst case
 831          * scenario, which is our best guess at the beginning of
 832          * the first and last frames.
 833          */
 834         lower_bound = first_frame_offset;
 835
 836         /* calc the upper_bound, beyond which we never want to seek */
 837         if(max_framesize > 0)
 838                 upper_bound = stream_length - (max_framesize + 128 + 2); /* 128 for a possible ID3V1 tag, 2 for indexing differences */
 839         else
 840                 upper_bound = stream_length - ((channels * bps * FLAC__MAX_BLOCK_SIZE) / 8 + 128 + 2);
 841
 842         /*
 843          * Now we refine the bounds if we have a seektable with
 844          * suitable points.  Note that according to the spec they
 845          * must be ordered by ascending sample number.
 846          */
 847         if(0 != decoder->private_->seek_table) {
 848                 /* find the closest seek point <= target_sample, if it exists */
 849                 for(i = (int)decoder->private_->seek_table->num_points - 1; i >= 0; i--) {
 850                         if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number <= target_sample)
 851                                 break;
 852                 }
 853                 if(i >= 0) { /* i.e. we found a suitable seek point... */
 854                         lower_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
 855                         lower_seek_point = i;
 856                 }
 857
 858                 /* find the closest seek point > target_sample, if it exists */
 859                 for(i = 0; i < (int)decoder->private_->seek_table->num_points; i++) {
 860                         if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number > target_sample)
 861                                 break;
 862                 }
 863                 if(i < (int)decoder->private_->seek_table->num_points) { /* i.e. we found a suitable seek point... */
 864                         upper_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
 865                         upper_seek_point = i;
 866                 }
 867         }
 868
 869         /*
 870          * Now guess at where within those bounds our target
 871          * sample will be.
 872          */
 873         if(lower_seek_point >= 0) {
 874                 /* first see if our sample is within a few frames of the lower seekpoint */
 875                 if(decoder->private_->seek_table->points[lower_seek_point].sample_number <= target_sample && target_sample < decoder->private_->seek_table->points[lower_seek_point].sample_number + (decoder->private_->seek_table->points[lower_seek_point].frame_samples * 4)) {
 876                         pos = (FLAC__int64)lower_bound;
 877                 }
 878                 else if(upper_seek_point >= 0) {
 879                         const FLAC__uint64 target_offset = target_sample - decoder->private_->seek_table->points[lower_seek_point].sample_number;
 880                         const FLAC__uint64 range_samples = decoder->private_->seek_table->points[upper_seek_point].sample_number - decoder->private_->seek_table->points[lower_seek_point].sample_number;
 881                         const FLAC__uint64 range_bytes = upper_bound - lower_bound;
 882 #if defined _MSC_VER || defined __MINGW32__
 883                         /* with VC++ you have to spoon feed it the casting */
 884                         pos = (FLAC__int64)lower_bound + (FLAC__int64)((double)(FLAC__int64)target_offset / (double)(FLAC__int64)range_samples * (double)(FLAC__int64)(range_bytes-1)) - approx_bytes_per_frame;
 885 #else
 886                         pos = (FLAC__int64)lower_bound + (FLAC__int64)((double)target_offset / (double)range_samples * (double)(range_bytes-1)) - approx_bytes_per_frame;
 887 #endif
 888                 }
 889         }
 890
 891         /*
 892          * If there's no seek table, we need to use the metadata (if we
 893          * have it) and the filelength to estimate the position of the
 894          * frame with the correct sample.
 895          */
 896         if(pos < 0 && total_samples > 0) {
 897 #if defined _MSC_VER || defined __MINGW32__
 898                 /* with VC++ you have to spoon feed it the casting */
 899                 pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((double)(FLAC__int64)target_sample / (double)(FLAC__int64)total_samples * (double)(FLAC__int64)(stream_length-first_frame_offset-1)) - approx_bytes_per_frame;
 900 #else
 901                 pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((double)target_sample / (double)total_samples * (double)(stream_length-first_frame_offset-1)) - approx_bytes_per_frame;
 902 #endif
 903         }
 904
 905         /*
 906          * If there's no seek table and total_samples is unknown, we
 907          * don't even bother trying to figure out a target, we just use
 908          * our current position.
 909          */
 910         if(pos < 0) {
 911                 FLAC__uint64 upos;
 912                 if(decoder->private_->tell_callback(decoder, &upos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 913                         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 914                         return false;
 915                 }
 916                 pos = (FLAC__int32)upos;
 917                 needs_seek = false;
 918         }
 919         else
 920                 needs_seek = true;
 921
 922         /* clip the position to the bounds, lower bound takes precedence */
 923         if(pos >= (FLAC__int64)upper_bound) {
 924                 pos = (FLAC__int64)upper_bound-1;
 925                 needs_seek = true;
 926         }
 927         if(pos < (FLAC__int64)lower_bound) {
 928                 pos = (FLAC__int64)lower_bound;
 929                 needs_seek = true;
 930         }
 931
 932         decoder->private_->target_sample = target_sample;
 933         while(1) {
 934                 if(needs_seek) {
 935                         if(decoder->private_->seek_callback(decoder, (FLAC__uint64)pos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
 936                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 937                                 return false;
 938                         }
 939                         if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
 940                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 941                                 return false;
 942                         }
 943                 }
 944                 if(!FLAC__stream_decoder_process_single(decoder->private_->stream_decoder)) {
 945                         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 946                         return false;
 947                 }
 948                 /* our write callback will change the state when it gets to the target frame */
 949                 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 950                         break;
 951                 }
 952                 else { /* we need to narrow the search */
 953                         FLAC__uint64 this_frame_sample = decoder->private_->last_frame.header.number.sample_number;
 954                         FLAC__ASSERT(decoder->private_->last_frame.header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
 955                         if(this_frame_sample == last_frame_sample) {
 956                                 /* our last move backwards wasn't big enough */
 957                                 pos -= (last_pos - pos);
 958                                 needs_seek = true;
 959                         }
 960                         else {
 961                                 if(target_sample < this_frame_sample) {
 962                                         last_pos = pos;
 963                                         approx_bytes_per_frame = decoder->private_->last_frame.header.blocksize * channels * bps/8 + 64;
 964                                         pos -= approx_bytes_per_frame;
 965                                         needs_seek = true;
 966                                 }
 967                                 else { /* target_sample >= this_frame_sample + this frame's blocksize */
 968                                         FLAC__uint64 upos;
 969                                         if(decoder->private_->tell_callback(decoder, &upos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 970                                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 971                                                 return false;
 972                                         }
 973                                         last_pos = pos;
 974                                         pos = (FLAC__int32)upos;
 975                                         pos -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
 976                                         needs_seek = false;
 977                                 }
 978                         }
 979                         if(pos < (FLAC__int64)lower_bound)
 980                                 pos = (FLAC__int64)lower_bound;
 981                         last_frame_sample = this_frame_sample;
 982                 }
 983         }
 984
 985         return true;
 986 }