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 seekable_stream_decoder_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 *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__SeekableStreamDecoderReadStatus (*read_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data);
  49         FLAC__SeekableStreamDecoderSeekStatus (*seek_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data);
  50         FLAC__SeekableStreamDecoderTellStatus (*tell_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data);
  51         FLAC__SeekableStreamDecoderLengthStatus (*length_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data);
  52         FLAC__bool (*eof_callback)(const FLAC__SeekableStreamDecoder *decoder, void *client_data);
  53         FLAC__StreamDecoderWriteStatus (*write_callback)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 *buffer[], void *client_data);
  54         void (*metadata_callback)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__StreamMetaData *metadata, void *client_data);
  55         void (*error_callback)(const FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data);
  56         void *client_data;
  57         FLAC__StreamDecoder *stream_decoder;
  58         struct MD5Context md5context;
  59         FLAC__byte stored_md5sum[16]; /* this is what is stored in the metadata */
  60         FLAC__byte computed_md5sum[16]; /* this is the sum we computed from the decoded data */
  61         /* the rest of these are only used for seeking: */
  62         FLAC__StreamMetaData_StreamInfo stream_info; /* we keep this around so we can figure out how to seek quickly */
  63         const FLAC__StreamMetaData_SeekTable *seek_table; /* we hold a pointer to the stream decoder's seek table for the same reason */
  64         FLAC__Frame last_frame; /* holds the info of the last frame we seeked to */
  65         FLAC__uint64 target_sample;
  66 } FLAC__SeekableStreamDecoderPrivate;
  67
  68 /***********************************************************************
  69  *
  70  * Public static class data
  71  *
  72  ***********************************************************************/
  73
  74 const char *FLAC__SeekableStreamDecoderStateString[] = {
  75         "FLAC__SEEKABLE_STREAM_DECODER_OK",
  76         "FLAC__SEEKABLE_STREAM_DECODER_SEEKING",
  77         "FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM",
  78         "FLAC__SEEKABLE_STREAM_DECODER_MEMORY_ALLOCATION_ERROR",
  79         "FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR",
  80         "FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR",
  81         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR",
  82     "FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED",
  83     "FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK",
  84     "FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED"
  85 };
  86
  87 const char *FLAC__SeekableStreamDecoderReadStatusString[] = {
  88         "FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_OK",
  89         "FLAC__SEEKABLE_STREAM_DECODER_READ_STATUS_ERROR"
  90 };
  91
  92 const char *FLAC__SeekableStreamDecoderSeekStatusString[] = {
  93         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK",
  94         "FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_ERROR"
  95 };
  96
  97 const char *FLAC__SeekableStreamDecoderTellStatusString[] = {
  98         "FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK",
  99         "FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_ERROR"
 100 };
 101
 102 const char *FLAC__SeekableStreamDecoderLengthStatusString[] = {
 103         "FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK",
 104         "FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_ERROR"
 105 };
 106
 107 /***********************************************************************
 108  *
 109  * Class constructor/destructor
 110  *
 111  ***********************************************************************/
 112
 113 FLAC__SeekableStreamDecoder *FLAC__seekable_stream_decoder_new()
 114 {
 115         FLAC__SeekableStreamDecoder *decoder;
 116
 117         FLAC__ASSERT(sizeof(int) >= 4); /* we want to die right away if this is not true */
 118
 119         decoder = (FLAC__SeekableStreamDecoder*)malloc(sizeof(FLAC__SeekableStreamDecoder));
 120         if(decoder == 0) {
 121                 return 0;
 122         }
 123         decoder->protected_ = (FLAC__SeekableStreamDecoderProtected*)malloc(sizeof(FLAC__SeekableStreamDecoderProtected));
 124         if(decoder->protected_ == 0) {
 125                 free(decoder);
 126                 return 0;
 127         }
 128         decoder->private_ = (FLAC__SeekableStreamDecoderPrivate*)malloc(sizeof(FLAC__SeekableStreamDecoderPrivate));
 129         if(decoder->private_ == 0) {
 130                 free(decoder->protected_);
 131                 free(decoder);
 132                 return 0;
 133         }
 134
 135         decoder->private_->stream_decoder = FLAC__stream_decoder_new();
 136
 137         if(0 == decoder->private_->stream_decoder) {
 138                 free(decoder->private_);
 139                 free(decoder->protected_);
 140                 free(decoder);
 141                 return 0;
 142         }
 143
 144         seekable_stream_decoder_set_defaults_(decoder);
 145
 146         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
 147
 148         return decoder;
 149 }
 150
 151 void FLAC__seekable_stream_decoder_delete(FLAC__SeekableStreamDecoder *decoder)
 152 {
 153         FLAC__ASSERT(decoder != 0);
 154         FLAC__ASSERT(decoder->protected_ != 0);
 155         FLAC__ASSERT(decoder->private_ != 0);
 156
 157         if(decoder->private_->stream_decoder != 0)
 158                 FLAC__stream_decoder_delete(decoder->private_->stream_decoder);
 159
 160         free(decoder->private_);
 161         free(decoder->protected_);
 162         free(decoder);
 163 }
 164
 165 /***********************************************************************
 166  *
 167  * Public class methods
 168  *
 169  ***********************************************************************/
 170
 171 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_init(FLAC__SeekableStreamDecoder *decoder)
 172 {
 173         FLAC__ASSERT(decoder != 0);
 174
 175         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 176                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_ALREADY_INITIALIZED;
 177
 178         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 179
 180         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)
 181                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
 182
 183         if(0 == decoder->private_->write_callback || 0 == decoder->private_->metadata_callback || 0 == decoder->private_->error_callback)
 184                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_INVALID_CALLBACK;
 185
 186         decoder->private_->seek_table = 0;
 187
 188         /* We initialize the MD5Context even though we may never use it.  This is
 189          * because md5_checking may be turned on to start and then turned off if a
 190          * seek occurs.  So we always init the context here and finalize it in
 191          * FLAC__seekable_stream_decoder_finish() to make sure things are always
 192          * cleaned up properly.
 193          */
 194         MD5Init(&decoder->private_->md5context);
 195
 196         FLAC__stream_decoder_set_read_callback(decoder->private_->stream_decoder, read_callback_);
 197         FLAC__stream_decoder_set_write_callback(decoder->private_->stream_decoder, write_callback_);
 198         FLAC__stream_decoder_set_metadata_callback(decoder->private_->stream_decoder, metadata_callback_);
 199         FLAC__stream_decoder_set_error_callback(decoder->private_->stream_decoder, error_callback_);
 200         FLAC__stream_decoder_set_client_data(decoder->private_->stream_decoder, decoder);
 201
 202         if(FLAC__stream_decoder_init(decoder->private_->stream_decoder) != FLAC__STREAM_DECODER_SEARCH_FOR_METADATA)
 203                 return decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 204
 205         return decoder->protected_->state;
 206 }
 207
 208 FLAC__bool FLAC__seekable_stream_decoder_finish(FLAC__SeekableStreamDecoder *decoder)
 209 {
 210         FLAC__bool md5_failed = false;
 211
 212         FLAC__ASSERT(decoder != 0);
 213         FLAC__ASSERT(decoder->private_ != 0);
 214         FLAC__ASSERT(decoder->protected_ != 0);
 215
 216         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 217                 return true;
 218
 219         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 220
 221         /* see the comment in FLAC__seekable_stream_decoder_init() as to why we
 222          * always call MD5Final()
 223          */
 224         MD5Final(decoder->private_->computed_md5sum, &decoder->private_->md5context);
 225
 226         FLAC__stream_decoder_finish(decoder->private_->stream_decoder);
 227
 228         if(decoder->protected_->md5_checking) {
 229                 if(memcmp(decoder->private_->stored_md5sum, decoder->private_->computed_md5sum, 16))
 230                         md5_failed = true;
 231         }
 232
 233         seekable_stream_decoder_set_defaults_(decoder);
 234
 235         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED;
 236
 237         return !md5_failed;
 238 }
 239
 240 FLAC__bool FLAC__seekable_stream_decoder_set_md5_checking(FLAC__SeekableStreamDecoder *decoder, FLAC__bool value)
 241 {
 242         FLAC__ASSERT(decoder != 0);
 243         FLAC__ASSERT(decoder->protected_ != 0);
 244         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 245                 return false;
 246         decoder->protected_->md5_checking = value;
 247         return true;
 248 }
 249
 250 FLAC__bool FLAC__seekable_stream_decoder_set_read_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderReadStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data))
 251 {
 252         FLAC__ASSERT(decoder != 0);
 253         FLAC__ASSERT(decoder->private_ != 0);
 254         FLAC__ASSERT(decoder->protected_ != 0);
 255         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 256                 return false;
 257         decoder->private_->read_callback = value;
 258         return true;
 259 }
 260
 261 FLAC__bool FLAC__seekable_stream_decoder_set_seek_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderSeekStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 absolute_byte_offset, void *client_data))
 262 {
 263         FLAC__ASSERT(decoder != 0);
 264         FLAC__ASSERT(decoder->private_ != 0);
 265         FLAC__ASSERT(decoder->protected_ != 0);
 266         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 267                 return false;
 268         decoder->private_->seek_callback = value;
 269         return true;
 270 }
 271
 272 FLAC__bool FLAC__seekable_stream_decoder_set_tell_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderTellStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *absolute_byte_offset, void *client_data))
 273 {
 274         FLAC__ASSERT(decoder != 0);
 275         FLAC__ASSERT(decoder->private_ != 0);
 276         FLAC__ASSERT(decoder->protected_ != 0);
 277         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 278                 return false;
 279         decoder->private_->tell_callback = value;
 280         return true;
 281 }
 282
 283 FLAC__bool FLAC__seekable_stream_decoder_set_length_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__SeekableStreamDecoderLengthStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 *stream_length, void *client_data))
 284 {
 285         FLAC__ASSERT(decoder != 0);
 286         FLAC__ASSERT(decoder->private_ != 0);
 287         FLAC__ASSERT(decoder->protected_ != 0);
 288         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 289                 return false;
 290         decoder->private_->length_callback = value;
 291         return true;
 292 }
 293
 294 FLAC__bool FLAC__seekable_stream_decoder_set_eof_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__bool (*value)(const FLAC__SeekableStreamDecoder *decoder, void *client_data))
 295 {
 296         FLAC__ASSERT(decoder != 0);
 297         FLAC__ASSERT(decoder->private_ != 0);
 298         FLAC__ASSERT(decoder->protected_ != 0);
 299         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 300                 return false;
 301         decoder->private_->eof_callback = value;
 302         return true;
 303 }
 304
 305 FLAC__bool FLAC__seekable_stream_decoder_set_write_callback(FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderWriteStatus (*value)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 *buffer[], void *client_data))
 306 {
 307         FLAC__ASSERT(decoder != 0);
 308         FLAC__ASSERT(decoder->private_ != 0);
 309         FLAC__ASSERT(decoder->protected_ != 0);
 310         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 311                 return false;
 312         decoder->private_->write_callback = value;
 313         return true;
 314 }
 315
 316 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_callback(FLAC__SeekableStreamDecoder *decoder, void (*value)(const FLAC__SeekableStreamDecoder *decoder, const FLAC__StreamMetaData *metadata, void *client_data))
 317 {
 318         FLAC__ASSERT(decoder != 0);
 319         FLAC__ASSERT(decoder->private_ != 0);
 320         FLAC__ASSERT(decoder->protected_ != 0);
 321         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 322                 return false;
 323         decoder->private_->metadata_callback = value;
 324         return true;
 325 }
 326
 327 FLAC__bool FLAC__seekable_stream_decoder_set_error_callback(FLAC__SeekableStreamDecoder *decoder, void (*value)(const FLAC__SeekableStreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data))
 328 {
 329         FLAC__ASSERT(decoder != 0);
 330         FLAC__ASSERT(decoder->private_ != 0);
 331         FLAC__ASSERT(decoder->protected_ != 0);
 332         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 333                 return false;
 334         decoder->private_->error_callback = value;
 335         return true;
 336 }
 337
 338 FLAC__bool FLAC__seekable_stream_decoder_set_client_data(FLAC__SeekableStreamDecoder *decoder, void *value)
 339 {
 340         FLAC__ASSERT(decoder != 0);
 341         FLAC__ASSERT(decoder->private_ != 0);
 342         FLAC__ASSERT(decoder->protected_ != 0);
 343         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 344                 return false;
 345         decoder->private_->client_data = value;
 346         return true;
 347 }
 348
 349 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond(FLAC__SeekableStreamDecoder *decoder, FLAC__MetaDataType type)
 350 {
 351         FLAC__ASSERT(decoder != 0);
 352         FLAC__ASSERT(decoder->private_ != 0);
 353         FLAC__ASSERT(decoder->protected_ != 0);
 354         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 355         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 356                 return false;
 357         return FLAC__stream_decoder_set_metadata_respond(decoder->private_->stream_decoder, type);
 358 }
 359
 360 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond_application(FLAC__SeekableStreamDecoder *decoder, const FLAC__byte id[4])
 361 {
 362         FLAC__ASSERT(decoder != 0);
 363         FLAC__ASSERT(decoder->private_ != 0);
 364         FLAC__ASSERT(decoder->protected_ != 0);
 365         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 366         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 367                 return false;
 368         return FLAC__stream_decoder_set_metadata_respond_application(decoder->private_->stream_decoder, id);
 369 }
 370
 371 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_respond_all(FLAC__SeekableStreamDecoder *decoder)
 372 {
 373         FLAC__ASSERT(decoder != 0);
 374         FLAC__ASSERT(decoder->private_ != 0);
 375         FLAC__ASSERT(decoder->protected_ != 0);
 376         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 377         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 378                 return false;
 379         return FLAC__stream_decoder_set_metadata_respond_all(decoder->private_->stream_decoder);
 380 }
 381
 382 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore(FLAC__SeekableStreamDecoder *decoder, FLAC__MetaDataType type)
 383 {
 384         FLAC__ASSERT(decoder != 0);
 385         FLAC__ASSERT(decoder->private_ != 0);
 386         FLAC__ASSERT(decoder->protected_ != 0);
 387         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 388         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 389                 return false;
 390         return FLAC__stream_decoder_set_metadata_ignore(decoder->private_->stream_decoder, type);
 391 }
 392
 393 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore_application(FLAC__SeekableStreamDecoder *decoder, const FLAC__byte id[4])
 394 {
 395         FLAC__ASSERT(decoder != 0);
 396         FLAC__ASSERT(decoder->private_ != 0);
 397         FLAC__ASSERT(decoder->protected_ != 0);
 398         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 399         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 400                 return false;
 401         return FLAC__stream_decoder_set_metadata_ignore_application(decoder->private_->stream_decoder, id);
 402 }
 403
 404 FLAC__bool FLAC__seekable_stream_decoder_set_metadata_ignore_all(FLAC__SeekableStreamDecoder *decoder)
 405 {
 406         FLAC__ASSERT(decoder != 0);
 407         FLAC__ASSERT(decoder->private_ != 0);
 408         FLAC__ASSERT(decoder->protected_ != 0);
 409         FLAC__ASSERT(decoder->private_->stream_decoder != 0);
 410         if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_UNINITIALIZED)
 411                 return false;
 412         return FLAC__stream_decoder_set_metadata_ignore_all(decoder->private_->stream_decoder);
 413 }
 414
 415 FLAC__SeekableStreamDecoderState FLAC__seekable_stream_decoder_get_state(const FLAC__SeekableStreamDecoder *decoder)
 416 {
 417         FLAC__ASSERT(decoder != 0);
 418         FLAC__ASSERT(decoder->protected_ != 0);
 419         return decoder->protected_->state;
 420 }
 421
 422 FLAC__bool FLAC__seekable_stream_decoder_get_md5_checking(const FLAC__SeekableStreamDecoder *decoder)
 423 {
 424         FLAC__ASSERT(decoder != 0);
 425         FLAC__ASSERT(decoder->protected_ != 0);
 426         return decoder->protected_->md5_checking;
 427 }
 428
 429 unsigned FLAC__seekable_stream_decoder_get_channels(const FLAC__SeekableStreamDecoder *decoder)
 430 {
 431     FLAC__ASSERT(decoder != 0);
 432     FLAC__ASSERT(decoder->private_ != 0);
 433     return FLAC__stream_decoder_get_channels(decoder->private_->stream_decoder);
 434 }
 435
 436 FLAC__ChannelAssignment FLAC__seekable_stream_decoder_get_channel_assignment(const FLAC__SeekableStreamDecoder *decoder)
 437 {
 438     FLAC__ASSERT(decoder != 0);
 439     FLAC__ASSERT(decoder->private_ != 0);
 440     return FLAC__stream_decoder_get_channel_assignment(decoder->private_->stream_decoder);
 441 }
 442
 443 unsigned FLAC__seekable_stream_decoder_get_bits_per_sample(const FLAC__SeekableStreamDecoder *decoder)
 444 {
 445     FLAC__ASSERT(decoder != 0);
 446     FLAC__ASSERT(decoder->private_ != 0);
 447     return FLAC__stream_decoder_get_bits_per_sample(decoder->private_->stream_decoder);
 448 }
 449
 450 unsigned FLAC__seekable_stream_decoder_get_sample_rate(const FLAC__SeekableStreamDecoder *decoder)
 451 {
 452     FLAC__ASSERT(decoder != 0);
 453     FLAC__ASSERT(decoder->private_ != 0);
 454     return FLAC__stream_decoder_get_sample_rate(decoder->private_->stream_decoder);
 455 }
 456
 457 unsigned FLAC__seekable_stream_decoder_get_blocksize(const FLAC__SeekableStreamDecoder *decoder)
 458 {
 459     FLAC__ASSERT(decoder != 0);
 460     FLAC__ASSERT(decoder->private_ != 0);
 461     return FLAC__stream_decoder_get_blocksize(decoder->private_->stream_decoder);
 462 }
 463
 464 FLAC__bool FLAC__seekable_stream_decoder_flush(FLAC__SeekableStreamDecoder *decoder)
 465 {
 466         FLAC__ASSERT(decoder != 0);
 467         FLAC__ASSERT(decoder->private_ != 0);
 468         FLAC__ASSERT(decoder->protected_ != 0);
 469
 470         decoder->protected_->md5_checking = false;
 471
 472         if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
 473                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 474                 return false;
 475         }
 476
 477         return true;
 478 }
 479
 480 FLAC__bool FLAC__seekable_stream_decoder_reset(FLAC__SeekableStreamDecoder *decoder)
 481 {
 482         FLAC__ASSERT(decoder != 0);
 483         FLAC__ASSERT(decoder->private_ != 0);
 484         FLAC__ASSERT(decoder->protected_ != 0);
 485
 486         if(!FLAC__seekable_stream_decoder_flush(decoder)) {
 487                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 488                 return false;
 489         }
 490
 491         if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
 492                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 493                 return false;
 494         }
 495
 496         decoder->private_->seek_table = 0;
 497
 498         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 499
 500         return true;
 501 }
 502
 503 FLAC__bool FLAC__seekable_stream_decoder_process_whole_stream(FLAC__SeekableStreamDecoder *decoder)
 504 {
 505         FLAC__bool ret;
 506         FLAC__ASSERT(decoder != 0);
 507
 508         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 509                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 510
 511         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 512                 return true;
 513
 514         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 515
 516         ret = FLAC__stream_decoder_process_whole_stream(decoder->private_->stream_decoder);
 517         if(!ret)
 518                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 519
 520         return ret;
 521 }
 522
 523 FLAC__bool FLAC__seekable_stream_decoder_process_metadata(FLAC__SeekableStreamDecoder *decoder)
 524 {
 525         FLAC__bool ret;
 526         FLAC__ASSERT(decoder != 0);
 527
 528         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 529                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 530
 531         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 532                 return true;
 533
 534         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 535
 536         ret = FLAC__stream_decoder_process_metadata(decoder->private_->stream_decoder);
 537         if(!ret)
 538                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 539
 540         return ret;
 541 }
 542
 543 FLAC__bool FLAC__seekable_stream_decoder_process_one_frame(FLAC__SeekableStreamDecoder *decoder)
 544 {
 545         FLAC__bool ret;
 546         FLAC__ASSERT(decoder != 0);
 547
 548         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 549                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 550
 551         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 552                 return true;
 553
 554         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 555
 556         ret = FLAC__stream_decoder_process_one_frame(decoder->private_->stream_decoder);
 557         if(!ret)
 558                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 559
 560         return ret;
 561 }
 562
 563 FLAC__bool FLAC__seekable_stream_decoder_process_remaining_frames(FLAC__SeekableStreamDecoder *decoder)
 564 {
 565         FLAC__bool ret;
 566         FLAC__ASSERT(decoder != 0);
 567
 568         if(decoder->private_->stream_decoder->protected_->state == FLAC__STREAM_DECODER_END_OF_STREAM)
 569                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 570
 571         if(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM)
 572                 return true;
 573
 574         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK);
 575
 576         ret = FLAC__stream_decoder_process_remaining_frames(decoder->private_->stream_decoder);
 577         if(!ret)
 578                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 579
 580         return ret;
 581 }
 582
 583 FLAC__bool FLAC__seekable_stream_decoder_seek_absolute(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 sample)
 584 {
 585         FLAC__uint64 length;
 586
 587         FLAC__ASSERT(decoder != 0);
 588         FLAC__ASSERT(decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_OK || decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM);
 589
 590         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEKING;
 591
 592         /* turn off md5 checking if a seek is attempted */
 593         decoder->protected_->md5_checking = false;
 594
 595         if(!FLAC__stream_decoder_reset(decoder->private_->stream_decoder)) {
 596                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 597                 return false;
 598         }
 599         /* get the file length */
 600         if(decoder->private_->length_callback(decoder, &length, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_LENGTH_STATUS_OK) {
 601                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 602                 return false;
 603         }
 604         /* rewind */
 605         if(decoder->private_->seek_callback(decoder, 0, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
 606                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 607                 return false;
 608         }
 609         if(!FLAC__stream_decoder_process_metadata(decoder->private_->stream_decoder)) {
 610                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 611                 return false;
 612         }
 613         if(sample > decoder->private_->stream_info.total_samples) {
 614                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 615                 return false;
 616         }
 617
 618         return seek_to_absolute_sample_(decoder, length, sample);
 619 }
 620
 621 /***********************************************************************
 622  *
 623  * Private class methods
 624  *
 625  ***********************************************************************/
 626
 627 void seekable_stream_decoder_set_defaults_(FLAC__SeekableStreamDecoder *decoder)
 628 {
 629         decoder->private_->read_callback = 0;
 630         decoder->private_->seek_callback = 0;
 631         decoder->private_->tell_callback = 0;
 632         decoder->private_->length_callback = 0;
 633         decoder->private_->eof_callback = 0;
 634         decoder->private_->write_callback = 0;
 635         decoder->private_->metadata_callback = 0;
 636         decoder->private_->error_callback = 0;
 637         decoder->private_->client_data = 0;
 638
 639         decoder->protected_->md5_checking = false;
 640 }
 641
 642 FLAC__StreamDecoderReadStatus read_callback_(const FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void *client_data)
 643 {
 644         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 645         (void)decoder;
 646         if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
 647                 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 648                 return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 649         }
 650         else if(*bytes > 0) {
 651                 unsigned bytes_read = *bytes;
 652                 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) {
 653                         seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_READ_ERROR;
 654                         return FLAC__STREAM_DECODER_READ_STATUS_ABORT;
 655                 }
 656                 if(bytes_read == 0) {
 657                         if(seekable_stream_decoder->private_->eof_callback(seekable_stream_decoder, seekable_stream_decoder->private_->client_data)) {
 658                                 seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_END_OF_STREAM;
 659                                 return FLAC__STREAM_DECODER_READ_STATUS_END_OF_STREAM;
 660                         }
 661                         else
 662                                 return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
 663                 }
 664                 else {
 665                         *bytes = bytes_read;
 666                         return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
 667                 }
 668         }
 669         else
 670                 return FLAC__STREAM_DECODER_READ_STATUS_ABORT; /* abort to avoid a deadlock */
 671 }
 672
 673 FLAC__StreamDecoderWriteStatus write_callback_(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 *buffer[], void *client_data)
 674 {
 675         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 676         (void)decoder;
 677
 678         if(seekable_stream_decoder->protected_->state == FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 679                 FLAC__uint64 this_frame_sample = frame->header.number.sample_number;
 680                 FLAC__uint64 next_frame_sample = this_frame_sample + (FLAC__uint64)frame->header.blocksize;
 681                 FLAC__uint64 target_sample = seekable_stream_decoder->private_->target_sample;
 682
 683                 FLAC__ASSERT(frame->header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
 684
 685                 seekable_stream_decoder->private_->last_frame = *frame; /* save the frame */
 686                 if(this_frame_sample <= target_sample && target_sample < next_frame_sample) { /* we hit our target frame */
 687                         unsigned delta = (unsigned)(target_sample - this_frame_sample);
 688                         /* kick out of seek mode */
 689                         seekable_stream_decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_OK;
 690                         /* shift out the samples before target_sample */
 691                         if(delta > 0) {
 692                                 unsigned channel;
 693                                 const FLAC__int32 *newbuffer[FLAC__MAX_CHANNELS];
 694                                 for(channel = 0; channel < frame->header.channels; channel++)
 695                                         newbuffer[channel] = buffer[channel] + delta;
 696                                 seekable_stream_decoder->private_->last_frame.header.blocksize -= delta;
 697                                 seekable_stream_decoder->private_->last_frame.header.number.sample_number += (FLAC__uint64)delta;
 698                                 /* write the relevant samples */
 699                                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, &seekable_stream_decoder->private_->last_frame, newbuffer, seekable_stream_decoder->private_->client_data);
 700                         }
 701                         else {
 702                                 /* write the relevant samples */
 703                                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
 704                         }
 705                 }
 706                 else {
 707                         return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
 708                 }
 709         }
 710         else {
 711                 if(seekable_stream_decoder->protected_->md5_checking) {
 712                         if(!FLAC__MD5Accumulate(&seekable_stream_decoder->private_->md5context, buffer, frame->header.channels, frame->header.blocksize, (frame->header.bits_per_sample+7) / 8))
 713                                 return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
 714                 }
 715                 return seekable_stream_decoder->private_->write_callback(seekable_stream_decoder, frame, buffer, seekable_stream_decoder->private_->client_data);
 716         }
 717 }
 718
 719 void metadata_callback_(const FLAC__StreamDecoder *decoder, const FLAC__StreamMetaData *metadata, void *client_data)
 720 {
 721         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 722         (void)decoder;
 723
 724         if(metadata->type == FLAC__METADATA_TYPE_STREAMINFO) {
 725                 seekable_stream_decoder->private_->stream_info = metadata->data.stream_info;
 726                 /* save the MD5 signature for comparison later */
 727                 memcpy(seekable_stream_decoder->private_->stored_md5sum, metadata->data.stream_info.md5sum, 16);
 728                 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))
 729                         seekable_stream_decoder->protected_->md5_checking = false;
 730         }
 731         else if(metadata->type == FLAC__METADATA_TYPE_SEEKTABLE) {
 732                 seekable_stream_decoder->private_->seek_table = &metadata->data.seek_table;
 733         }
 734
 735         if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING)
 736                 seekable_stream_decoder->private_->metadata_callback(seekable_stream_decoder, metadata, seekable_stream_decoder->private_->client_data);
 737 }
 738
 739 void error_callback_(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus status, void *client_data)
 740 {
 741         FLAC__SeekableStreamDecoder *seekable_stream_decoder = (FLAC__SeekableStreamDecoder *)client_data;
 742         (void)decoder;
 743
 744         if(seekable_stream_decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING)
 745                 seekable_stream_decoder->private_->error_callback(seekable_stream_decoder, status, seekable_stream_decoder->private_->client_data);
 746 }
 747
 748 FLAC__bool seek_to_absolute_sample_(FLAC__SeekableStreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample)
 749 {
 750         FLAC__uint64 first_frame_offset, lower_bound, upper_bound;
 751         FLAC__int64 pos = -1, last_pos = -1;
 752         int i, lower_seek_point = -1, upper_seek_point = -1;
 753         unsigned approx_bytes_per_frame;
 754         FLAC__uint64 last_frame_sample = 0xffffffffffffffff;
 755         FLAC__bool needs_seek;
 756         const FLAC__bool is_variable_blocksize_stream = (decoder->private_->stream_info.min_blocksize != decoder->private_->stream_info.max_blocksize);
 757
 758         /* we are just guessing here, but we want to guess high, not low */
 759         if(decoder->private_->stream_info.max_framesize > 0) {
 760                 approx_bytes_per_frame = decoder->private_->stream_info.max_framesize;
 761         }
 762         else if(!is_variable_blocksize_stream) {
 763                 /* note there are no () around 'decoder->private_->stream_info.bits_per_sample/8' to keep precision up since it's an integer calulation */
 764                 approx_bytes_per_frame = decoder->private_->stream_info.min_blocksize * decoder->private_->stream_info.channels * decoder->private_->stream_info.bits_per_sample/8 + 64;
 765         }
 766         else
 767                 approx_bytes_per_frame = 1152 * decoder->private_->stream_info.channels * decoder->private_->stream_info.bits_per_sample/8 + 64;
 768
 769         /*
 770          * The stream position is currently at the first frame plus any read
 771          * ahead data, so first we get the stream position, then subtract
 772          * uncomsumed bytes to get the position of the first frame in the
 773          * stream.
 774          */
 775         if(decoder->private_->tell_callback(decoder, &first_frame_offset, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 776                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 777                 return false;
 778         }
 779         FLAC__ASSERT(first_frame_offset >= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder));
 780         first_frame_offset -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
 781
 782         /*
 783          * First, we set an upper and lower bound on where in the
 784          * stream we will search.  For now we assume the worst case
 785          * scenario, which is our best guess at the beginning of
 786          * the first and last frames.
 787          */
 788         lower_bound = first_frame_offset;
 789
 790         /* calc the upper_bound, beyond which we never want to seek */
 791         if(decoder->private_->stream_info.max_framesize > 0)
 792                 upper_bound = stream_length - (decoder->private_->stream_info.max_framesize + 128 + 2); /* 128 for a possible ID3V1 tag, 2 for indexing differences */
 793         else
 794                 upper_bound = stream_length - ((decoder->private_->stream_info.channels * decoder->private_->stream_info.bits_per_sample * FLAC__MAX_BLOCK_SIZE) / 8 + 128 + 2);
 795
 796         /*
 797          * Now we refine the bounds if we have a seektable with
 798          * suitable points.  Note that according to the spec they
 799          * must be ordered by ascending sample number.
 800          */
 801         if(0 != decoder->private_->seek_table) {
 802                 /* find the closest seek point <= target_sample, if it exists */
 803                 for(i = (int)decoder->private_->seek_table->num_points - 1; i >= 0; i--) {
 804                         if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number <= target_sample)
 805                                 break;
 806                 }
 807                 if(i >= 0) { /* i.e. we found a suitable seek point... */
 808                         lower_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
 809                         lower_seek_point = i;
 810                 }
 811
 812                 /* find the closest seek point > target_sample, if it exists */
 813                 for(i = 0; i < (int)decoder->private_->seek_table->num_points; i++) {
 814                         if(decoder->private_->seek_table->points[i].sample_number != FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER && decoder->private_->seek_table->points[i].sample_number > target_sample)
 815                                 break;
 816                 }
 817                 if(i < (int)decoder->private_->seek_table->num_points) { /* i.e. we found a suitable seek point... */
 818                         upper_bound = first_frame_offset + decoder->private_->seek_table->points[i].stream_offset;
 819                         upper_seek_point = i;
 820                 }
 821         }
 822
 823         /*
 824          * Now guess at where within those bounds our target
 825          * sample will be.
 826          */
 827         if(lower_seek_point >= 0) {
 828                 /* first see if our sample is within a few frames of the lower seekpoint */
 829                 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)) {
 830                         pos = (FLAC__int64)lower_bound;
 831                 }
 832                 else if(upper_seek_point >= 0) {
 833                         const FLAC__uint64 target_offset = target_sample - decoder->private_->seek_table->points[lower_seek_point].sample_number;
 834                         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;
 835                         const FLAC__uint64 range_bytes = upper_bound - lower_bound;
 836 #if defined _MSC_VER || defined __MINGW32__
 837                         /* with VC++ you have to spoon feed it the casting */
 838                         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;
 839 #else
 840                         pos = (FLAC__int64)lower_bound + (FLAC__int64)((double)target_offset / (double)range_samples * (double)(range_bytes-1)) - approx_bytes_per_frame;
 841 #endif
 842                 }
 843         }
 844         if(pos < 0) {
 845                 /* We need to use the metadata and the filelength to estimate the position of the frame with the correct sample */
 846 #if defined _MSC_VER || defined __MINGW32__
 847                 /* with VC++ you have to spoon feed it the casting */
 848                 pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((double)(FLAC__int64)target_sample / (double)(FLAC__int64)decoder->private_->stream_info.total_samples * (double)(FLAC__int64)(stream_length-first_frame_offset-1)) - approx_bytes_per_frame;
 849 #else
 850                 pos = (FLAC__int64)first_frame_offset + (FLAC__int64)((double)target_sample / (double)decoder->private_->stream_info.total_samples * (double)(stream_length-first_frame_offset-1)) - approx_bytes_per_frame;
 851 #endif
 852         }
 853
 854         /* clip the position to the bounds, lower bound takes precedence */
 855         if(pos >= (FLAC__int64)upper_bound)
 856                 pos = (FLAC__int64)upper_bound-1;
 857         if(pos < (FLAC__int64)lower_bound)
 858                 pos = (FLAC__int64)lower_bound;
 859         needs_seek = true;
 860
 861         decoder->private_->target_sample = target_sample;
 862         while(1) {
 863                 if(needs_seek) {
 864                         if(decoder->private_->seek_callback(decoder, (FLAC__uint64)pos, decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_SEEK_STATUS_OK) {
 865                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 866                                 return false;
 867                         }
 868                         if(!FLAC__stream_decoder_flush(decoder->private_->stream_decoder)) {
 869                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_STREAM_DECODER_ERROR;
 870                                 return false;
 871                         }
 872                 }
 873                 if(!FLAC__stream_decoder_process_one_frame(decoder->private_->stream_decoder)) {
 874                         decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 875                         return false;
 876                 }
 877                 /* our write callback will change the state when it gets to the target frame */
 878                 if(decoder->protected_->state != FLAC__SEEKABLE_STREAM_DECODER_SEEKING) {
 879                         break;
 880                 }
 881                 else { /* we need to narrow the search */
 882                         FLAC__uint64 this_frame_sample = decoder->private_->last_frame.header.number.sample_number;
 883                         FLAC__ASSERT(decoder->private_->last_frame.header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);
 884                         if(this_frame_sample == last_frame_sample) {
 885                                 /* our last move backwards wasn't big enough */
 886                                 pos -= (last_pos - pos);
 887                                 needs_seek = true;
 888                         }
 889                         else {
 890                                 if(target_sample < this_frame_sample) {
 891                                         last_pos = pos;
 892                                         approx_bytes_per_frame = decoder->private_->last_frame.header.blocksize * decoder->private_->last_frame.header.channels * decoder->private_->last_frame.header.bits_per_sample/8 + 64;
 893                                         pos -= approx_bytes_per_frame;
 894                                         needs_seek = true;
 895                                 }
 896                                 else { /* target_sample >= this_frame_sample + this frame's blocksize */
 897                                         last_pos = pos;
 898                                         if(decoder->private_->tell_callback(decoder, (FLAC__uint64*)(&pos), decoder->private_->client_data) != FLAC__SEEKABLE_STREAM_DECODER_TELL_STATUS_OK) {
 899                                                 decoder->protected_->state = FLAC__SEEKABLE_STREAM_DECODER_SEEK_ERROR;
 900                                                 return false;
 901                                         }
 902                                         pos -= FLAC__stream_decoder_get_input_bytes_unconsumed(decoder->private_->stream_decoder);
 903                                         needs_seek = false;
 904                                 }
 905                         }
 906                         if(pos < (FLAC__int64)lower_bound)
 907                                 pos = (FLAC__int64)lower_bound;
 908                         last_frame_sample = this_frame_sample;
 909                 }
 910         }
 911
 912         return true;
 913 }