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