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