apps/pcmbuf.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2005 by Miika Pekkarinen
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include <stdio.h>
  22 #include "config.h"
  23 #include "system.h"
  24 #include "debug.h"
  25 #include <kernel.h>
  26 #include "pcmbuf.h"
  27 #include "pcm.h"
  28 #include "logf.h"
  29 #ifndef SIMULATOR
  30 #include "cpu.h"
  31 #endif
  32 #include <string.h>
  33 #include "buffer.h"
  34 #include "settings.h"
  35 #include "audio.h"
  36 #include "voice_thread.h"
  37 #include "dsp.h"
  38 #include "thread.h"
  39
  40 /* Clip sample to signed 16 bit range */
  41 static inline int32_t clip_sample_16(int32_t sample)
  42 {
  43     if ((int16_t)sample != sample)
  44         sample = 0x7fff ^ (sample >> 31);
  45     return sample;
  46 }
  47
  48 #if MEMORYSIZE > 2
  49 /* Keep watermark high for iPods at least (2s) */
  50 #define PCMBUF_WATERMARK     (NATIVE_FREQUENCY * 4 * 2)
  51 #else
  52 #define PCMBUF_WATERMARK     (NATIVE_FREQUENCY * 1) /* 0.25 seconds */
  53 #endif
  54
  55 /* Structure we can use to queue pcm chunks in memory to be played
  56  * by the driver code. */
  57 struct pcmbufdesc
  58 {
  59     void *addr;
  60     size_t size;
  61     struct pcmbufdesc* link;
  62     /* Call this when the buffer has been played */
  63     void (*callback)(void);
  64 };
  65
  66 #define PCMBUF_DESCS(bufsize) \
  67     ((bufsize) / PCMBUF_MINAVG_CHUNK)
  68 #define PCMBUF_DESCS_SIZE(bufsize) \
  69     (PCMBUF_DESCS(bufsize)*sizeof(struct pcmbufdesc))
  70
  71 /* Size of the PCM buffer. */
  72 static size_t pcmbuf_size IDATA_ATTR = 0;
  73 static char *pcmbuf_bufend IDATA_ATTR;
  74 static char *audiobuffer IDATA_ATTR;
  75 /* Current audio buffer write index. */
  76 static size_t audiobuffer_pos IDATA_ATTR;
  77 /* Amount audiobuffer_pos will be increased.*/
  78 static size_t audiobuffer_fillpos IDATA_ATTR;
  79 static char *fadebuf IDATA_ATTR;
  80 static char *voicebuf IDATA_ATTR;
  81
  82 static void (*pcmbuf_event_handler)(void) IDATA_ATTR;
  83 static void (*position_callback)(size_t size) IDATA_ATTR;
  84
  85 /* Crossfade related state */
  86 static bool crossfade_enabled;
  87 static bool crossfade_enabled_pending;
  88 static bool crossfade_mixmode;
  89 static bool crossfade_active IDATA_ATTR;
  90 static bool crossfade_init IDATA_ATTR;
  91
  92 /* Track the current location for processing crossfade */
  93 static struct pcmbufdesc *crossfade_chunk IDATA_ATTR;
  94 static size_t crossfade_sample IDATA_ATTR;
  95
  96 /* Counters for fading in new data */
  97 static size_t crossfade_fade_in_total IDATA_ATTR;
  98 static size_t crossfade_fade_in_rem IDATA_ATTR;
  99
 100 static struct pcmbufdesc *pcmbuf_read IDATA_ATTR;
 101 static struct pcmbufdesc *pcmbuf_read_end IDATA_ATTR;
 102 static struct pcmbufdesc *pcmbuf_write IDATA_ATTR;
 103 static struct pcmbufdesc *pcmbuf_write_end IDATA_ATTR;
 104 static size_t last_chunksize IDATA_ATTR;
 105
 106 static size_t pcmbuf_unplayed_bytes IDATA_ATTR;
 107 static size_t pcmbuf_watermark IDATA_ATTR;
 108
 109 static struct pcmbufdesc *pcmbuf_mix_chunk IDATA_ATTR;
 110 static size_t pcmbuf_mix_sample IDATA_ATTR;
 111
 112 static bool low_latency_mode = false;
 113 static bool pcmbuf_flush;
 114
 115 #ifdef HAVE_PRIORITY_SCHEDULING
 116 static int codec_thread_priority = PRIORITY_PLAYBACK;
 117 #endif
 118
 119 extern unsigned int codec_thread_id;
 120
 121 /* Helpful macros for use in conditionals this assumes some of the above
 122  * static variable names */
 123 #define NEED_FLUSH(position) \
 124     (audiobuffer_fillpos > PCMBUF_TARGET_CHUNK || position >= pcmbuf_size)
 125 #define LOW_DATA(quarter_secs) \
 126     (pcmbuf_unplayed_bytes < NATIVE_FREQUENCY * quarter_secs)
 127
 128 static bool prepare_insert(size_t length);
 129 static void pcmbuf_under_watermark(bool under);
 130 static bool pcmbuf_flush_fillpos(void);
 131
 132 #define CALL_IF_EXISTS(function, args...) if (function) function(args)
 133 /* This function has 2 major logical parts (separated by brackets both for
 134  * readability and variable scoping).  The first part performs the
 135  * operastions related to finishing off the last buffer we fed to the DMA.
 136  * The second part performs the operations involved in sending a new buffer
 137  * to the DMA.  Finally the function checks the status of the buffer and
 138  * boosts if necessary */
 139 static void pcmbuf_callback(unsigned char** start, size_t* size) ICODE_ATTR;
 140 static void pcmbuf_callback(unsigned char** start, size_t* size)
 141 {
 142     {
 143         struct pcmbufdesc *pcmbuf_current = pcmbuf_read;
 144         /* Take the finished buffer out of circulation */
 145         pcmbuf_read = pcmbuf_current->link;
 146
 147         /* The buffer is finished, call the callback functions */
 148         CALL_IF_EXISTS(position_callback, last_chunksize);
 149         CALL_IF_EXISTS(pcmbuf_current->callback);
 150
 151         /* Put the finished buffer back into circulation */
 152         pcmbuf_write_end->link = pcmbuf_current;
 153         pcmbuf_write_end = pcmbuf_current;
 154
 155         /* If we've read over the mix chunk while it's still mixing there */
 156         if (pcmbuf_current == pcmbuf_mix_chunk)
 157             pcmbuf_mix_chunk = NULL;
 158         /* If we've read over the crossfade chunk while it's still fading */
 159         if (pcmbuf_current == crossfade_chunk)
 160             crossfade_chunk = pcmbuf_read;
 161     }
 162
 163     {
 164         /* Send the new buffer to the pcm */
 165         struct pcmbufdesc *pcmbuf_new = pcmbuf_read;
 166         size_t *realsize = size;
 167         unsigned char** realstart = start;
 168         if(pcmbuf_new)
 169         {
 170             size_t current_size = pcmbuf_new->size;
 171
 172             pcmbuf_unplayed_bytes -= current_size;
 173             last_chunksize = current_size;
 174             *realsize = current_size;
 175             *realstart = pcmbuf_new->addr;
 176         }
 177         else
 178         {
 179             /* No more buffers */
 180             last_chunksize = 0;
 181             *realsize = 0;
 182             *realstart = NULL;
 183             CALL_IF_EXISTS(pcmbuf_event_handler);
 184         }
 185     }
 186 }
 187
 188 void pcmbuf_set_position_callback(void (*callback)(size_t size))
 189 {
 190     position_callback = callback;
 191 }
 192
 193 static void pcmbuf_set_watermark_bytes(void)
 194 {
 195     pcmbuf_watermark = (crossfade_enabled && pcmbuf_size) ?
 196         /* If crossfading, try to keep the buffer full other than 1 second */
 197         (pcmbuf_size - (NATIVE_FREQUENCY * 4 * 1)) :
 198         /* Otherwise, just use the default */
 199         PCMBUF_WATERMARK;
 200 }
 201
 202 /* This is really just part of pcmbuf_flush_fillpos, but is easier to keep
 203  * in a separate function for the moment */
 204 static inline void pcmbuf_add_chunk(void)
 205 {
 206     register size_t size = audiobuffer_fillpos;
 207     /* Grab the next description to write, and change the write pointer */
 208     register struct pcmbufdesc *pcmbuf_current = pcmbuf_write;
 209     pcmbuf_write = pcmbuf_current->link;
 210     /* Fill in the values in the new buffer chunk */
 211     pcmbuf_current->addr = &audiobuffer[audiobuffer_pos];
 212     pcmbuf_current->size = size;
 213     pcmbuf_current->callback = pcmbuf_event_handler;
 214     pcmbuf_current->link = NULL;
 215     /* This is single use only */
 216     pcmbuf_event_handler = NULL;
 217     if (pcmbuf_read != NULL) {
 218         if (pcmbuf_flush)
 219         {
 220             pcmbuf_write_end->link = pcmbuf_read->link;
 221             pcmbuf_read->link = pcmbuf_current;
 222             while (pcmbuf_write_end->link)
 223             {
 224                 pcmbuf_write_end = pcmbuf_write_end->link;
 225                 pcmbuf_unplayed_bytes -= pcmbuf_write_end->size;
 226             }
 227             pcmbuf_flush = false;
 228         }
 229         /* If there is already a read buffer setup, add to it */
 230         else
 231             pcmbuf_read_end->link = pcmbuf_current;
 232     } else {
 233         /* Otherwise create the buffer */
 234         pcmbuf_read = pcmbuf_current;
 235     }
 236     /* This is now the last buffer to read */
 237     pcmbuf_read_end = pcmbuf_current;
 238
 239     /* Update bytes counters */
 240     pcmbuf_unplayed_bytes += size;
 241
 242     audiobuffer_pos += size;
 243     if (audiobuffer_pos >= pcmbuf_size)
 244         audiobuffer_pos -= pcmbuf_size;
 245
 246     audiobuffer_fillpos = 0;
 247 }
 248
 249 #ifdef HAVE_PRIORITY_SCHEDULING
 250 static void boost_codec_thread(bool boost)
 251 {
 252     /* Keep voice and codec threads at the same priority or else voice
 253      * will starve if the codec thread's priority is boosted. */
 254     if (boost)
 255     {
 256         int priority = (PRIORITY_PLAYBACK - PRIORITY_PLAYBACK_MAX)*pcmbuf_unplayed_bytes
 257                           / (2*NATIVE_FREQUENCY) + PRIORITY_PLAYBACK_MAX;
 258
 259         if (priority != codec_thread_priority)
 260         {
 261             codec_thread_priority = priority;
 262             thread_set_priority(codec_thread_id, priority);
 263             voice_thread_set_priority(priority);
 264         }
 265     }
 266     else if (codec_thread_priority != PRIORITY_PLAYBACK)
 267     {
 268         thread_set_priority(codec_thread_id, PRIORITY_PLAYBACK);
 269         voice_thread_set_priority(PRIORITY_PLAYBACK);
 270         codec_thread_priority = PRIORITY_PLAYBACK;
 271     }
 272 }
 273 #endif /* HAVE_PRIORITY_SCHEDULING */
 274
 275 static void pcmbuf_under_watermark(bool under)
 276 {
 277     /* Only codec thread initiates boost - voice boosts the cpu when playing
 278        a clip */
 279 #ifndef SIMULATOR
 280     if (thread_get_current() == codec_thread_id)
 281 #endif /* SIMULATOR */
 282     {
 283         if (under)
 284         {
 285             /* Fill audio buffer by boosting cpu */
 286             trigger_cpu_boost();
 287 #ifdef HAVE_PRIORITY_SCHEDULING
 288             /* If buffer is critically low, override UI priority, else
 289                set back to the original priority. */
 290             boost_codec_thread(LOW_DATA(2) && pcm_is_playing());
 291 #endif
 292         }
 293         else
 294         {
 295 #ifdef HAVE_PRIORITY_SCHEDULING
 296             boost_codec_thread(false);
 297 #endif
 298         }
 299     }
 300
 301     /* Disable crossfade if < .5s of audio */
 302     if (LOW_DATA(2))
 303     {
 304         crossfade_active = false;
 305     }
 306 }
 307
 308 void pcmbuf_set_event_handler(void (*event_handler)(void))
 309 {
 310     pcmbuf_event_handler = event_handler;
 311 }
 312
 313 unsigned int pcmbuf_get_latency(void)
 314 {
 315     /* Be careful how this calculation is rearranged, it's easy to overflow */
 316     size_t bytes = pcmbuf_unplayed_bytes + pcm_get_bytes_waiting();
 317     return bytes / 4 / (NATIVE_FREQUENCY/1000);
 318 }
 319
 320 void pcmbuf_set_low_latency(bool state)
 321 {
 322     low_latency_mode = state;
 323 }
 324
 325 bool pcmbuf_is_lowdata(void)
 326 {
 327     if (!pcm_is_playing() || pcm_is_paused() ||
 328             crossfade_init || crossfade_active)
 329         return false;
 330
 331 #if MEMORYSIZE > 2
 332     /* 1 seconds of buffer is low data */
 333     return LOW_DATA(4);
 334 #else
 335     /* under watermark is low data */
 336     return (pcmbuf_unplayed_bytes < pcmbuf_watermark);
 337 #endif
 338 }
 339
 340 /* Amount of bytes left in the buffer. */
 341 inline size_t pcmbuf_free(void)
 342 {
 343     if (pcmbuf_read != NULL)
 344     {
 345         void *read = pcmbuf_read->addr;
 346         void *write = &audiobuffer[audiobuffer_pos + audiobuffer_fillpos];
 347         if (read < write)
 348             return (size_t)(read - write) + pcmbuf_size;
 349         else
 350             return (size_t) (read - write);
 351     }
 352     return pcmbuf_size;
 353 }
 354
 355 bool pcmbuf_crossfade_init(bool manual_skip)
 356 {
 357     /* Can't do two crossfades at once and, no fade if pcm is off now */
 358     if (crossfade_init || crossfade_active || !pcm_is_playing())
 359     {
 360         pcmbuf_play_stop();
 361         return false;
 362     }
 363
 364     trigger_cpu_boost();
 365
 366     /* Not enough data, or crossfade disabled, flush the old data instead */
 367     if (LOW_DATA(2) || !pcmbuf_is_crossfade_enabled() || low_latency_mode)
 368     {
 369         pcmbuf_flush_fillpos();
 370         pcmbuf_flush = true;
 371         return false;
 372     }
 373
 374     /* Don't enable mix mode when skipping tracks manually. */
 375     if (manual_skip)
 376         crossfade_mixmode = false;
 377     else
 378         crossfade_mixmode = global_settings.crossfade_fade_out_mixmode;
 379
 380     crossfade_init = true;
 381
 382     return true;
 383
 384 }
 385
 386 void pcmbuf_play_stop(void)
 387 {
 388     pcm_play_stop();
 389
 390     pcmbuf_unplayed_bytes = 0;
 391     pcmbuf_mix_chunk = NULL;
 392     if (pcmbuf_read) {
 393         pcmbuf_write_end->link = pcmbuf_read;
 394         pcmbuf_write_end = pcmbuf_read_end;
 395         pcmbuf_read = pcmbuf_read_end = NULL;
 396     }
 397     audiobuffer_pos = 0;
 398     audiobuffer_fillpos = 0;
 399     crossfade_init = false;
 400     crossfade_active = false;
 401     pcmbuf_flush = false;
 402
 403 #ifdef HAVE_PRIORITY_SCHEDULING
 404     /* Can unboost the codec thread here no matter who's calling */
 405     boost_codec_thread(false);
 406 #endif
 407 }
 408
 409 int pcmbuf_used_descs(void)
 410 {
 411     struct pcmbufdesc *pcmbuf_temp = pcmbuf_read;
 412     unsigned int i = 0;
 413     while (pcmbuf_temp) {
 414         pcmbuf_temp = pcmbuf_temp->link;
 415         i++;
 416     }
 417     return i;
 418 }
 419
 420 int pcmbuf_descs(void)
 421 {
 422     return PCMBUF_DESCS(pcmbuf_size);
 423 }
 424
 425 static void pcmbuf_init_pcmbuffers(void)
 426 {
 427     struct pcmbufdesc *next = pcmbuf_write;
 428     next++;
 429     pcmbuf_write_end = pcmbuf_write;
 430     while ((void *)next < (void *)pcmbuf_bufend) {
 431         pcmbuf_write_end->link=next;
 432         pcmbuf_write_end=next;
 433         next++;
 434     }
 435 }
 436
 437 static size_t pcmbuf_get_next_required_pcmbuf_size(void)
 438 {
 439     size_t seconds = 1;
 440
 441     if (crossfade_enabled_pending)
 442         seconds += global_settings.crossfade_fade_out_delay
 443                    + global_settings.crossfade_fade_out_duration;
 444
 445 #if MEMORYSIZE > 2
 446     /* Buffer has to be at least 2s long. */
 447     seconds += 2;
 448 #endif
 449     logf("pcmbuf len: %ld", seconds);
 450     return seconds * (NATIVE_FREQUENCY*4); /* 2 channels + 2 bytes/sample */
 451 }
 452
 453 static char *pcmbuf_calc_audiobuffer_ptr(size_t bufsize)
 454 {
 455     return pcmbuf_bufend - (bufsize + PCMBUF_MIX_CHUNK * 2 +
 456                PCMBUF_DESCS_SIZE(bufsize));
 457 }
 458
 459 bool pcmbuf_is_same_size(void)
 460 {
 461     if (audiobuffer == NULL)
 462         return true; /* Not set up yet even once so always */
 463
 464     size_t bufsize = pcmbuf_get_next_required_pcmbuf_size();
 465     return pcmbuf_calc_audiobuffer_ptr(bufsize) == audiobuffer;
 466 }
 467
 468 /* Initialize the pcmbuffer the structure looks like this:
 469  * ...|---------PCMBUF---------|FADEBUF|VOICEBUF|DESCS|... */
 470 size_t pcmbuf_init(unsigned char *bufend)
 471 {
 472     pcmbuf_bufend = bufend;
 473     pcmbuf_size = pcmbuf_get_next_required_pcmbuf_size();
 474     audiobuffer = pcmbuf_calc_audiobuffer_ptr(pcmbuf_size);
 475     fadebuf = &audiobuffer[pcmbuf_size];
 476     voicebuf = &fadebuf[PCMBUF_MIX_CHUNK];
 477     pcmbuf_write = (struct pcmbufdesc *)&voicebuf[PCMBUF_MIX_CHUNK];
 478
 479     pcmbuf_init_pcmbuffers();
 480
 481     position_callback = NULL;
 482     pcmbuf_event_handler = NULL;
 483
 484     pcmbuf_crossfade_enable_finished();
 485
 486     pcmbuf_play_stop();
 487
 488     return pcmbuf_bufend - audiobuffer;
 489 }
 490
 491 size_t pcmbuf_get_bufsize(void)
 492 {
 493     return pcmbuf_size;
 494 }
 495
 496 #ifdef ROCKBOX_HAS_LOGF
 497 unsigned char * pcmbuf_get_meminfo(size_t *length)
 498 {
 499     *length = pcmbuf_bufend - audiobuffer;
 500     return audiobuffer;
 501 }
 502 #endif
 503
 504 void pcmbuf_pause(bool pause)
 505 {
 506     if (pcm_is_playing())
 507         pcm_play_pause(!pause);
 508     else if (!pause)
 509         pcmbuf_play_start();
 510 }
 511
 512 /* Force playback. */
 513 void pcmbuf_play_start(void)
 514 {
 515     if (!pcm_is_playing() && pcmbuf_unplayed_bytes && pcmbuf_read != NULL)
 516     {
 517         last_chunksize = pcmbuf_read->size;
 518         pcmbuf_unplayed_bytes -= last_chunksize;
 519         pcm_play_data(pcmbuf_callback,
 520             (unsigned char *)pcmbuf_read->addr, last_chunksize);
 521     }
 522 }
 523
 524 /**
 525  * Commit samples waiting to the pcm buffer.
 526  */
 527 static bool pcmbuf_flush_fillpos(void)
 528 {
 529     if (audiobuffer_fillpos) {
 530         /* Never use the last buffer descriptor */
 531         while (pcmbuf_write == pcmbuf_write_end) {
 532             /* If this happens, something is being stupid */
 533             if (!pcm_is_playing()) {
 534                 logf("pcmbuf_flush_fillpos error");
 535                 pcmbuf_play_start();
 536             }
 537             /* Let approximately one chunk of data playback */
 538             sleep(HZ*PCMBUF_TARGET_CHUNK/(NATIVE_FREQUENCY*4));
 539         }
 540         pcmbuf_add_chunk();
 541         return true;
 542     }
 543     return false;
 544 }
 545
 546 /**
 547  * Completely process the crossfade fade out effect with current pcm buffer.
 548  */
 549 static void crossfade_process_buffer(size_t fade_in_delay,
 550         size_t fade_out_delay, size_t fade_out_rem)
 551 {
 552     if (!crossfade_mixmode)
 553     {
 554         /* Fade out the specified amount of the already processed audio */
 555         size_t total_fade_out = fade_out_rem;
 556         size_t fade_out_sample;
 557         struct pcmbufdesc *fade_out_chunk = crossfade_chunk;
 558
 559         /* Find the right chunk to start fading out */
 560         fade_out_delay += crossfade_sample * 2;
 561         while (fade_out_delay != 0 && fade_out_delay >= fade_out_chunk->size)
 562         {
 563             fade_out_delay -= fade_out_chunk->size;
 564             fade_out_chunk = fade_out_chunk->link;
 565         }
 566         /* The start sample within the chunk */
 567         fade_out_sample = fade_out_delay / 2;
 568
 569         while (fade_out_rem > 0)
 570         {
 571             /* Each 1/10 second of audio will have the same fade applied */
 572             size_t block_rem = MIN(NATIVE_FREQUENCY * 4 / 10, fade_out_rem);
 573             int factor = (fade_out_rem << 8) / total_fade_out;
 574
 575             fade_out_rem -= block_rem;
 576
 577             /* Fade this block */
 578             while (block_rem > 0 && fade_out_chunk != NULL)
 579             {
 580                 /* Fade one sample */
 581                 int16_t *buf = (int16_t *)fade_out_chunk->addr;
 582                 int32_t sample = buf[fade_out_sample];
 583                 buf[fade_out_sample++] = (sample * factor) >> 8;
 584
 585                 block_rem -= 2;
 586                 /* Move to the next chunk as needed */
 587                 if (fade_out_sample * 2 >= fade_out_chunk->size)
 588                 {
 589                     fade_out_chunk = fade_out_chunk->link;
 590                     fade_out_sample = 0;
 591                 }
 592             }
 593         }
 594     }
 595
 596     /* Find the right chunk and sample to start fading in */
 597     fade_in_delay += crossfade_sample * 2;
 598     while (fade_in_delay != 0 && fade_in_delay >= crossfade_chunk->size)
 599     {
 600         fade_in_delay -= crossfade_chunk->size;
 601         crossfade_chunk = crossfade_chunk->link;
 602     }
 603     crossfade_sample = fade_in_delay / 2;
 604     logf("process done!");
 605 }
 606
 607 /* Initializes crossfader, calculates all necessary parameters and
 608  * performs fade-out with the pcm buffer.  */
 609 static void crossfade_start(void)
 610 {
 611     size_t crossfade_rem;
 612     size_t crossfade_need;
 613     size_t fade_out_rem;
 614     size_t fade_out_delay;
 615     size_t fade_in_delay;
 616
 617     crossfade_init = false;
 618     /* Reject crossfade if less than .5s of data */
 619     if (LOW_DATA(2)) {
 620         logf("crossfade rejected");
 621         pcmbuf_play_stop();
 622         return ;
 623     }
 624
 625     logf("crossfade_start");
 626     pcmbuf_flush_fillpos();
 627     crossfade_active = true;
 628
 629     /* Initialize the crossfade buffer size to all of the buffered data that
 630      * has not yet been sent to the DMA */
 631     crossfade_rem = pcmbuf_unplayed_bytes;
 632     crossfade_chunk = pcmbuf_read->link;
 633     crossfade_sample = 0;
 634
 635     /* Get fade out delay from settings. */
 636     fade_out_delay =
 637         NATIVE_FREQUENCY * global_settings.crossfade_fade_out_delay * 4;
 638
 639     /* Get fade out duration from settings. */
 640     fade_out_rem =
 641         NATIVE_FREQUENCY * global_settings.crossfade_fade_out_duration * 4;
 642
 643     crossfade_need = fade_out_delay + fade_out_rem;
 644     /* We want only to modify the last part of the buffer. */
 645     if (crossfade_rem > crossfade_need)
 646     {
 647         size_t crossfade_extra = crossfade_rem - crossfade_need;
 648         while (crossfade_extra > crossfade_chunk->size)
 649         {
 650             crossfade_extra -= crossfade_chunk->size;
 651             crossfade_chunk = crossfade_chunk->link;
 652         }
 653         crossfade_sample = crossfade_extra / 2;
 654     }
 655     /* Truncate fade out duration if necessary. */
 656     else if (crossfade_rem < crossfade_need)
 657     {
 658         size_t crossfade_short = crossfade_need - crossfade_rem;
 659         if (fade_out_rem >= crossfade_short)
 660             fade_out_rem -= crossfade_short;
 661         else
 662         {
 663             fade_out_delay -= crossfade_short - fade_out_rem;
 664             fade_out_rem = 0;
 665         }
 666     }
 667
 668     /* Get also fade in duration and delays from settings. */
 669     crossfade_fade_in_total =
 670         NATIVE_FREQUENCY * global_settings.crossfade_fade_in_duration * 4;
 671     crossfade_fade_in_rem = crossfade_fade_in_total;
 672
 673     fade_in_delay =
 674         NATIVE_FREQUENCY * global_settings.crossfade_fade_in_delay * 4;
 675
 676     crossfade_process_buffer(fade_in_delay, fade_out_delay, fade_out_rem);
 677 }
 678
 679 /* Returns the number of bytes _NOT_ mixed */
 680 static size_t crossfade_fade_mix(int factor, const char *buf, size_t fade_rem)
 681 {
 682     const int16_t *input_buf = (const int16_t *)buf;
 683     int16_t *output_buf = (int16_t *)(crossfade_chunk->addr);
 684     int16_t *chunk_end = SKIPBYTES(output_buf, crossfade_chunk->size);
 685     output_buf = &output_buf[crossfade_sample];
 686     int32_t sample;
 687
 688     while (fade_rem)
 689     {
 690         /* fade left and right channel at once to keep buffer alignment */
 691         sample = *input_buf++;
 692         sample = ((sample * factor) >> 8) + *output_buf;
 693         *output_buf++ = clip_sample_16(sample);
 694
 695         sample = *input_buf++;
 696         sample = ((sample * factor) >> 8) + *output_buf;
 697         *output_buf++ = clip_sample_16(sample);
 698
 699         fade_rem -= 4; /* 2 samples, each 16 bit -> 4 bytes */
 700
 701         if (output_buf >= chunk_end)
 702         {
 703             crossfade_chunk = crossfade_chunk->link;
 704             if (!crossfade_chunk)
 705                 return fade_rem;
 706             output_buf = (int16_t *)crossfade_chunk->addr;
 707             chunk_end = SKIPBYTES(output_buf, crossfade_chunk->size);
 708         }
 709     }
 710     crossfade_sample = output_buf - (int16_t *)crossfade_chunk->addr;
 711     return 0;
 712 }
 713
 714 /* Returns the number of bytes _NOT_ mixed */
 715 static size_t crossfade_mix(const char *buf, size_t length)
 716 {
 717     const int16_t *input_buf = (const int16_t *)buf;
 718     int16_t *output_buf = (int16_t *)crossfade_chunk->addr;
 719     int16_t *chunk_end = SKIPBYTES(output_buf, crossfade_chunk->size);
 720     output_buf = &output_buf[crossfade_sample];
 721     int32_t sample;
 722
 723     while (length)
 724     {
 725         /* fade left and right channel at once to keep buffer alignment */
 726         sample = *input_buf++ + *output_buf;
 727         *output_buf++ = clip_sample_16(sample);
 728
 729         sample = *input_buf++ + *output_buf;
 730         *output_buf++ = clip_sample_16(sample);
 731
 732         length -= 4; /* 2 samples, each 16 bit -> 4 bytes */
 733
 734         if (output_buf >= chunk_end)
 735         {
 736             crossfade_chunk = crossfade_chunk->link;
 737             if (!crossfade_chunk)
 738                 return length;
 739
 740             output_buf = (int16_t *)crossfade_chunk->addr;
 741             chunk_end = SKIPBYTES(output_buf, crossfade_chunk->size);
 742         }
 743     }
 744     crossfade_sample = output_buf - (int16_t *)crossfade_chunk->addr;
 745     return 0;
 746 }
 747
 748 static void pcmbuf_flush_buffer(const char *buf, size_t length)
 749 {
 750     size_t copy_n;
 751     while (length > 0) {
 752         size_t audiobuffer_index = audiobuffer_pos + audiobuffer_fillpos;
 753         if (NEED_FLUSH(audiobuffer_index))
 754         {
 755             pcmbuf_flush_fillpos();
 756             audiobuffer_index = audiobuffer_pos + audiobuffer_fillpos;
 757         }
 758         copy_n = MIN(length, pcmbuf_size - audiobuffer_index);
 759         memcpy(&audiobuffer[audiobuffer_index], buf, copy_n);
 760         buf += copy_n;
 761         audiobuffer_fillpos += copy_n;
 762         length -= copy_n;
 763     }
 764 }
 765
 766 static void flush_crossfade(char *buf, size_t length)
 767 {
 768     if (length)
 769     {
 770         if (crossfade_fade_in_rem)
 771         {
 772             size_t samples;
 773             int16_t *input_buf;
 774
 775             /* Fade factor for this packet */
 776             int factor =
 777                 ((crossfade_fade_in_total - crossfade_fade_in_rem) << 8) /
 778                 crossfade_fade_in_total;
 779             /* Bytes to fade */
 780             size_t fade_rem = MIN(length, crossfade_fade_in_rem);
 781
 782             /* We _will_ fade this many bytes */
 783             crossfade_fade_in_rem -= fade_rem;
 784
 785             if (crossfade_chunk)
 786             {
 787                 /* Mix the data */
 788                 size_t fade_total = fade_rem;
 789                 fade_rem = crossfade_fade_mix(factor, buf, fade_rem);
 790                 length -= fade_total - fade_rem;
 791                 buf += fade_total - fade_rem;
 792                 if (!length)
 793                     return;
 794                 if (!fade_rem)
 795                     goto fade_done;
 796             }
 797
 798             samples = fade_rem / 2;
 799             input_buf = (int16_t *)buf;
 800             /* Fade remaining samples in place */
 801             while (samples)
 802             {
 803                 int32_t sample = *input_buf;
 804                 *input_buf++ = (sample * factor) >> 8;
 805                 samples--;
 806             }
 807         }
 808
 809 fade_done:
 810         if (crossfade_chunk)
 811         {
 812             /* Mix the data */
 813             size_t mix_total = length;
 814             length = crossfade_mix(buf, length);
 815             buf += mix_total - length;
 816             if (!length)
 817                 return;
 818         }
 819
 820         /* Flush samples to the buffer */
 821         while (!prepare_insert(length))
 822             sleep(1);
 823         pcmbuf_flush_buffer(buf, length);
 824     }
 825
 826 }
 827
 828 static bool prepare_insert(size_t length)
 829 {
 830     if (low_latency_mode)
 831     {
 832         /* 1/4s latency. */
 833         if (!LOW_DATA(1) && pcm_is_playing())
 834             return false;
 835     }
 836
 837     /* Need to save PCMBUF_MIN_CHUNK to prevent wrapping overwriting */
 838     if (pcmbuf_free() < length + PCMBUF_MIN_CHUNK)
 839         return false;
 840
 841     if (!pcm_is_playing())
 842     {
 843         trigger_cpu_boost();
 844
 845         /* Pre-buffer up to watermark */
 846 #if MEMORYSIZE > 2
 847         if (!LOW_DATA(4))
 848 #else
 849         if (pcmbuf_unplayed_bytes > pcmbuf_watermark)
 850 #endif
 851         {
 852             logf("pcm starting");
 853             if (!(audio_status() & AUDIO_STATUS_PAUSE))
 854                 pcmbuf_play_start();
 855         }
 856     }
 857     else
 858         pcmbuf_under_watermark(pcmbuf_unplayed_bytes <= pcmbuf_watermark);
 859
 860     return true;
 861 }
 862
 863 void* pcmbuf_request_buffer(int *count)
 864 {
 865     if (crossfade_init)
 866         crossfade_start();
 867
 868     if (crossfade_active) {
 869         *count = MIN(*count, PCMBUF_MIX_CHUNK/4);
 870         return fadebuf;
 871     }
 872     else
 873     {
 874         if(prepare_insert(*count << 2))
 875         {
 876             size_t audiobuffer_index = audiobuffer_pos + audiobuffer_fillpos;
 877             if (pcmbuf_size - audiobuffer_index >= PCMBUF_MIN_CHUNK)
 878             {
 879                 /* Usual case, there's space here */
 880                 return &audiobuffer[audiobuffer_index];
 881             }
 882             else
 883             {
 884                 /* Flush and wrap the buffer */
 885                 pcmbuf_flush_fillpos();
 886                 audiobuffer_pos = 0;
 887                 return &audiobuffer[0];
 888             }
 889         }
 890         else
 891         {
 892             return NULL;
 893         }
 894     }
 895 }
 896
 897 void * pcmbuf_request_voice_buffer(int *count)
 898 {
 899     /* A get-it-to-work-for-now hack (audio status could change by
 900        completion) */
 901     if (audio_status() & AUDIO_STATUS_PLAY)
 902     {
 903         if (pcmbuf_read == NULL)
 904         {
 905             return NULL;
 906         }
 907         else if (pcmbuf_usage() >= 10 && pcmbuf_mix_free() >= 30 &&
 908                  (pcmbuf_mix_chunk || pcmbuf_read->link))
 909         {
 910             *count = MIN(*count, PCMBUF_MIX_CHUNK/4);
 911             return voicebuf;
 912         }
 913         else
 914         {
 915             return NULL;
 916         }
 917     }
 918     else
 919     {
 920         return pcmbuf_request_buffer(count);
 921     }
 922 }
 923
 924 bool pcmbuf_is_crossfade_active(void)
 925 {
 926     return crossfade_active || crossfade_init;
 927 }
 928
 929 void pcmbuf_write_complete(int count)
 930 {
 931     size_t length = (size_t)(unsigned int)count << 2;
 932
 933     if (crossfade_active)
 934     {
 935         flush_crossfade(fadebuf, length);
 936         if (!(crossfade_fade_in_rem || crossfade_chunk))
 937             crossfade_active = false;
 938     }
 939     else
 940     {
 941         audiobuffer_fillpos += length;
 942
 943         if (NEED_FLUSH(audiobuffer_pos + audiobuffer_fillpos))
 944             pcmbuf_flush_fillpos();
 945     }
 946 }
 947
 948 #if 0
 949 bool pcmbuf_insert_buffer(char *buf, int count)
 950 {
 951     size_t length = (size_t)(unsigned int)count << 2;
 952
 953     if (crossfade_active)
 954     {
 955         flush_crossfade(buf, length);
 956         if (!(crossfade_fade_in_rem || crossfade_chunk))
 957             crossfade_active = false;
 958     }
 959     else
 960     {
 961         if (!prepare_insert(length))
 962             return false;
 963         pcmbuf_flush_buffer(buf, length);
 964     }
 965     return true;
 966 }
 967 #endif
 968
 969 #ifndef HAVE_HARDWARE_BEEP
 970 #define MINIBUF_SAMPLES (NATIVE_FREQUENCY / 1000 * KEYCLICK_DURATION)
 971 #define MINIBUF_SIZE (MINIBUF_SAMPLES*4)
 972
 973 /* Generates a constant square wave sound with a given frequency
 974    in Hertz for a duration in milliseconds. */
 975 void pcmbuf_beep(unsigned int frequency, size_t duration, int amplitude)
 976 {
 977     unsigned int step = 0xffffffffu / NATIVE_FREQUENCY * frequency;
 978     int32_t phase = 0;
 979     int16_t *bufptr, *bufstart, *bufend;
 980     int32_t sample;
 981     int nsamples = NATIVE_FREQUENCY / 1000 * duration;
 982     bool mix = pcmbuf_read != NULL && pcmbuf_read->link != NULL;
 983     int i;
 984
 985     bufend = SKIPBYTES((int16_t *)audiobuffer, pcmbuf_size);
 986
 987     /* Find the insertion point and set bufstart to the start of it */
 988     if (mix)
 989     {
 990         /* Get the currently playing chunk at the current position. */
 991         bufstart = (int16_t *)pcm_play_dma_get_peak_buffer(&i);
 992
 993         /* If above isn't implemented or pcm is stopped, no beepeth. */
 994         if (!bufstart || !pcm_is_playing())
 995             return;
 996
 997         /* Give 5ms clearance. */
 998         bufstart += NATIVE_FREQUENCY * 4 / 200;
 999
1000 #ifdef HAVE_PCM_DMA_ADDRESS
1001         /* Returned peak addresses are DMA addresses */
1002         bufend = pcm_dma_addr(bufend);
1003 #endif
1004
1005         /* Wrapped above? */
1006         if (bufstart >= bufend)
1007             bufstart -= pcmbuf_size;
1008
1009         /* NOTE: On some targets using hardware DMA, cache range flushing may
1010          * be required or the writes may not be picked up by the controller.
1011          * An incremental flush should be done periodically during the mixdown. */
1012     }
1013     else if (nsamples <= MINIBUF_SAMPLES)
1014     {
1015         static int16_t minibuf[MINIBUF_SAMPLES*2] __attribute__((aligned(4)));
1016         /* Use mini buffer */
1017         bufstart = minibuf;
1018         bufend = SKIPBYTES(bufstart, MINIBUF_SIZE);
1019     }
1020     else if (audio_buffer_state() != AUDIOBUF_STATE_TRASHED)
1021     {
1022         /* Use audiobuffer */
1023         bufstart = (int16_t *)audiobuffer;
1024     }
1025     else
1026     {
1027         /* No place */
1028         return;
1029     }
1030
1031     bufptr = bufstart;
1032
1033     /* Mix square wave into buffer */
1034     for (i = 0; i < nsamples; ++i)
1035     {
1036         int32_t amp = (phase >> 31) ^ (int32_t)amplitude;
1037         sample = mix ? *bufptr : 0;
1038         *bufptr++ = clip_sample_16(sample + amp);
1039         if (bufptr >= bufend)
1040             bufptr = (int16_t *)audiobuffer;
1041         sample = mix ? *bufptr : 0;
1042         *bufptr++ = clip_sample_16(sample + amp);
1043         if (bufptr >= bufend)
1044             bufptr = (int16_t *)audiobuffer;
1045
1046         phase += step;
1047     }
1048
1049     pcm_play_lock();
1050 #ifdef HAVE_RECORDING
1051     pcm_rec_lock();
1052 #endif
1053
1054     /* Kick off playback if required and it won't interfere */
1055     if (!pcm_is_playing()
1056 #ifdef HAVE_RECORDING
1057         && !pcm_is_recording()
1058 #endif
1059         )
1060     {
1061         pcm_play_data(NULL, (unsigned char *)bufstart, nsamples * 4);
1062     }
1063
1064     pcm_play_unlock();
1065 #ifdef HAVE_RECORDING
1066     pcm_rec_unlock();
1067 #endif
1068 }
1069 #endif /* HAVE_HARDWARE_BEEP */
1070
1071 /* Returns pcm buffer usage in percents (0 to 100). */
1072 int pcmbuf_usage(void)
1073 {
1074     return pcmbuf_unplayed_bytes * 100 / pcmbuf_size;
1075 }
1076
1077 int pcmbuf_mix_free(void)
1078 {
1079     if (pcmbuf_mix_chunk)
1080     {
1081         size_t my_mix_end =
1082             (size_t)&((int16_t *)pcmbuf_mix_chunk->addr)[pcmbuf_mix_sample];
1083         size_t my_write_pos = (size_t)&audiobuffer[audiobuffer_pos];
1084         if (my_write_pos < my_mix_end)
1085             my_write_pos += pcmbuf_size;
1086         return (my_write_pos - my_mix_end) * 100 / pcmbuf_unplayed_bytes;
1087     }
1088     return 100;
1089 }
1090
1091 void pcmbuf_write_voice_complete(int count)
1092 {
1093     /* A get-it-to-work-for-now hack (audio status could have changed) */
1094     if (!(audio_status() & AUDIO_STATUS_PLAY))
1095     {
1096         pcmbuf_write_complete(count);
1097         return;
1098     }
1099
1100     int16_t *ibuf = (int16_t *)voicebuf;
1101     int16_t *obuf;
1102     size_t chunk_samples;
1103
1104     if (pcmbuf_mix_chunk == NULL && pcmbuf_read != NULL)
1105     {
1106         pcmbuf_mix_chunk = pcmbuf_read->link;
1107         /* Start 1/8s into the next chunk */
1108         pcmbuf_mix_sample = NATIVE_FREQUENCY * 4 / 16;
1109     }
1110
1111     if (!pcmbuf_mix_chunk)
1112         return;
1113
1114     obuf = (int16_t *)pcmbuf_mix_chunk->addr;
1115     chunk_samples = pcmbuf_mix_chunk->size / sizeof (int16_t);
1116
1117     count <<= 1;
1118
1119     while (count-- > 0)
1120     {
1121         int32_t sample = *ibuf++;
1122
1123         if (pcmbuf_mix_sample >= chunk_samples)
1124         {
1125             pcmbuf_mix_chunk = pcmbuf_mix_chunk->link;
1126             if (!pcmbuf_mix_chunk)
1127                 return;
1128             pcmbuf_mix_sample = 0;
1129             obuf = pcmbuf_mix_chunk->addr;
1130             chunk_samples = pcmbuf_mix_chunk->size / 2;
1131         }
1132         sample += obuf[pcmbuf_mix_sample] >> 2;
1133         obuf[pcmbuf_mix_sample++] = clip_sample_16(sample);
1134     }
1135 }
1136
1137 void pcmbuf_crossfade_enable(bool on_off)
1138 {
1139     /* Next setting to be used, not applied now */
1140     crossfade_enabled_pending = on_off;
1141 }
1142
1143 void pcmbuf_crossfade_enable_finished(void)
1144 {
1145     /* Copy the pending setting over now */
1146     crossfade_enabled = crossfade_enabled_pending;
1147     pcmbuf_set_watermark_bytes();
1148 }
1149
1150 bool pcmbuf_is_crossfade_enabled(void)
1151 {
1152     if (global_settings.crossfade == CROSSFADE_ENABLE_SHUFFLE)
1153         return global_settings.playlist_shuffle;
1154
1155     return crossfade_enabled;
1156 }