sound.c

   1 /* gameplaySP
   2  *
   3  * Copyright (C) 2006 Exophase <exophase@gmail.com>
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation; either version 2 of
   8  * the License, or (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20
  21 #include "common.h"
  22 #include <SDL.h>
  23 u32 global_enable_audio = 1;
  24
  25 direct_sound_struct direct_sound_channel[2];
  26 gbc_sound_struct gbc_sound_channel[4];
  27
  28 u32 sound_frequency = 44100;
  29
  30 SDL_AudioSpec sound_settings;
  31 SDL_mutex *sound_mutex;
  32 SDL_cond *sound_cv;
  33
  34 #ifdef PSP_BUILD
  35 u32 audio_buffer_size_number = 1;
  36 #else
  37 u32 audio_buffer_size_number = 8;
  38 #endif
  39
  40 u32 audio_buffer_size;
  41 u32 sound_on = 0;
  42 s16 sound_buffer[BUFFER_SIZE];
  43 u32 sound_buffer_base = 0;
  44
  45 u32 sound_last_cpu_ticks = 0;
  46 fixed16_16 gbc_sound_tick_step;
  47
  48 u32 sound_exit_flag;
  49
  50 // Queue 1, 2, or 4 samples to the top of the DS FIFO, wrap around circularly
  51
  52 #define sound_timer_queue(size, value)                                        \
  53   *((s##size *)(ds->fifo + ds->fifo_top)) = value;                            \
  54   ds->fifo_top = (ds->fifo_top + 1) % 32;                                     \
  55
  56 void sound_timer_queue8(u32 channel, u8 value)
  57 {
  58   direct_sound_struct *ds = direct_sound_channel + channel;
  59   sound_timer_queue(8, value);
  60 }
  61
  62 void sound_timer_queue16(u32 channel, u16 value)
  63 {
  64   direct_sound_struct *ds = direct_sound_channel + channel;
  65   sound_timer_queue(8, value & 0xFF);
  66   sound_timer_queue(8, value >> 8);
  67 }
  68
  69 void sound_timer_queue32(u32 channel, u32 value)
  70 {
  71   direct_sound_struct *ds = direct_sound_channel + channel;
  72
  73   sound_timer_queue(8, value & 0xFF);
  74   sound_timer_queue(8, (value >> 8) & 0xFF);
  75   sound_timer_queue(8, (value >> 16) & 0xFF);
  76   sound_timer_queue(8, value >> 24);
  77 }
  78
  79 // Unqueue 1 sample from the base of the DS FIFO and place it on the audio
  80 // buffer for as many samples as necessary. If the DS FIFO is 16 bytes or
  81 // smaller and if DMA is enabled for the sound channel initiate a DMA transfer
  82 // to the DS FIFO.
  83
  84 #define render_sample_null()                                                  \
  85
  86 #define render_sample_left()                                                  \
  87   sound_buffer[buffer_index] += current_sample +                              \
  88    fp16_16_to_u32((next_sample - current_sample) * fifo_fractional)           \
  89
  90 #define render_sample_right()                                                 \
  91   sound_buffer[buffer_index + 1] += current_sample +                          \
  92    fp16_16_to_u32((next_sample - current_sample) * fifo_fractional)           \
  93
  94 #define render_sample_both()                                                  \
  95   dest_sample = current_sample +                                              \
  96    fp16_16_to_u32((next_sample - current_sample) * fifo_fractional);          \
  97   sound_buffer[buffer_index] += dest_sample;                                  \
  98   sound_buffer[buffer_index + 1] += dest_sample                               \
  99
 100 #define render_samples(type)                                                  \
 101   while(fifo_fractional <= 0xFFFF)                                            \
 102   {                                                                           \
 103     render_sample_##type();                                                   \
 104     fifo_fractional += frequency_step;                                        \
 105     buffer_index = (buffer_index + 2) % BUFFER_SIZE;                          \
 106   }                                                                           \
 107
 108 void sound_timer(fixed16_16 frequency_step, u32 channel)
 109 {
 110   direct_sound_struct *ds = direct_sound_channel + channel;
 111
 112   fixed16_16 fifo_fractional = ds->fifo_fractional;
 113   u32 buffer_index = ds->buffer_index;
 114   s16 current_sample, next_sample, dest_sample;
 115
 116   current_sample = ds->fifo[ds->fifo_base] << 4;
 117   ds->fifo_base = (ds->fifo_base + 1) % 32;
 118   next_sample = ds->fifo[ds->fifo_base] << 4;
 119
 120   if(sound_on == 1)
 121   {
 122     if(ds->volume == DIRECT_SOUND_VOLUME_50)
 123     {
 124       current_sample >>= 1;
 125       next_sample >>= 1;
 126     }
 127
 128     switch(ds->status)
 129     {
 130       case DIRECT_SOUND_INACTIVE:
 131         render_samples(null);
 132         break;
 133
 134       case DIRECT_SOUND_RIGHT:
 135         render_samples(right);
 136         break;
 137
 138       case DIRECT_SOUND_LEFT:
 139         render_samples(left);
 140         break;
 141
 142       case DIRECT_SOUND_LEFTRIGHT:
 143         render_samples(both);
 144         break;
 145     }
 146   }
 147   else
 148   {
 149     render_samples(null);
 150   }
 151
 152   ds->buffer_index = buffer_index;
 153   ds->fifo_fractional = fp16_16_fractional_part(fifo_fractional);
 154
 155   if(((ds->fifo_top - ds->fifo_base) % 32) <= 16)
 156   {
 157     if(dma[1].direct_sound_channel == channel)
 158       dma_transfer(dma + 1);
 159
 160     if(dma[2].direct_sound_channel == channel)
 161       dma_transfer(dma + 2);
 162   }
 163 }
 164
 165 void sound_reset_fifo(u32 channel)
 166 {
 167   direct_sound_struct *ds = direct_sound_channel;
 168
 169   memset(ds->fifo, 0, 32);
 170 }
 171
 172 // Initial pattern data = 4bits (signed)
 173 // Channel volume = 12bits
 174 // Envelope volume = 14bits
 175 // Master volume = 2bits
 176
 177 // Recalculate left and right volume as volume changes.
 178 // To calculate the current sample, use (sample * volume) >> 16
 179
 180 // Square waves range from -8 (low) to 7 (high)
 181
 182 s8 square_pattern_duty[4][8] =
 183 {
 184   { 0xF8, 0xF8, 0xF8, 0xF8, 0x07, 0xF8, 0xF8, 0xF8 },
 185   { 0xF8, 0xF8, 0xF8, 0xF8, 0x07, 0x07, 0xF8, 0xF8 },
 186   { 0xF8, 0xF8, 0x07, 0x07, 0x07, 0x07, 0xF8, 0xF8 },
 187   { 0x07, 0x07, 0x07, 0x07, 0xF8, 0xF8, 0x07, 0x07 },
 188 };
 189
 190 s8 wave_samples[64];
 191
 192 u32 noise_table15[1024];
 193 u32 noise_table7[4];
 194
 195 u32 gbc_sound_master_volume_table[4] = { 1, 2, 4, 0 };
 196
 197 u32 gbc_sound_channel_volume_table[8] =
 198 {
 199   fixed_div(0, 7, 12),
 200   fixed_div(1, 7, 12),
 201   fixed_div(2, 7, 12),
 202   fixed_div(3, 7, 12),
 203   fixed_div(4, 7, 12),
 204   fixed_div(5, 7, 12),
 205   fixed_div(6, 7, 12),
 206   fixed_div(7, 7, 12)
 207 };
 208
 209 u32 gbc_sound_envelope_volume_table[16] =
 210 {
 211   fixed_div(0, 15, 14),
 212   fixed_div(1, 15, 14),
 213   fixed_div(2, 15, 14),
 214   fixed_div(3, 15, 14),
 215   fixed_div(4, 15, 14),
 216   fixed_div(5, 15, 14),
 217   fixed_div(6, 15, 14),
 218   fixed_div(7, 15, 14),
 219   fixed_div(8, 15, 14),
 220   fixed_div(9, 15, 14),
 221   fixed_div(10, 15, 14),
 222   fixed_div(11, 15, 14),
 223   fixed_div(12, 15, 14),
 224   fixed_div(13, 15, 14),
 225   fixed_div(14, 15, 14),
 226   fixed_div(15, 15, 14)
 227 };
 228
 229 u32 gbc_sound_buffer_index = 0;
 230 u32 gbc_sound_last_cpu_ticks = 0;
 231 u32 gbc_sound_partial_ticks = 0;
 232
 233 u32 gbc_sound_master_volume_left;
 234 u32 gbc_sound_master_volume_right;
 235 u32 gbc_sound_master_volume;
 236
 237 #define update_volume_channel_envelope(channel)                               \
 238   volume_##channel = gbc_sound_envelope_volume_table[envelope_volume] *       \
 239    gbc_sound_channel_volume_table[gbc_sound_master_volume_##channel] *        \
 240    gbc_sound_master_volume_table[gbc_sound_master_volume]                     \
 241
 242 #define update_volume_channel_noenvelope(channel)                             \
 243   volume_##channel = gs->wave_volume *                                        \
 244    gbc_sound_channel_volume_table[gbc_sound_master_volume_##channel] *        \
 245    gbc_sound_master_volume_table[gbc_sound_master_volume]                     \
 246
 247 #define update_volume(type)                                                   \
 248   update_volume_channel_##type(left);                                         \
 249   update_volume_channel_##type(right)                                         \
 250
 251 #define update_tone_sweep()                                                   \
 252   if(gs->sweep_status)                                                        \
 253   {                                                                           \
 254     u32 sweep_ticks = gs->sweep_ticks - 1;                                    \
 255                                                                               \
 256     if(sweep_ticks == 0)                                                      \
 257     {                                                                         \
 258       u32 rate = gs->rate;                                                    \
 259                                                                               \
 260       if(gs->sweep_direction)                                                 \
 261         rate = rate - (rate >> gs->sweep_shift);                              \
 262       else                                                                    \
 263         rate = rate + (rate >> gs->sweep_shift);                              \
 264                                                                               \
 265       if(rate > 2048)                                                         \
 266         rate = 2048;                                                          \
 267                                                                               \
 268       frequency_step = float_to_fp16_16(((131072.0 / (2048 - rate)) * 8.0) /  \
 269        sound_frequency);                                                      \
 270                                                                               \
 271       gs->frequency_step = frequency_step;                                    \
 272       gs->rate = rate;                                                        \
 273                                                                               \
 274       sweep_ticks = gs->sweep_initial_ticks;                                  \
 275     }                                                                         \
 276     gs->sweep_ticks = sweep_ticks;                                            \
 277   }                                                                           \
 278
 279 #define update_tone_nosweep()                                                 \
 280
 281 #define update_tone_envelope()                                                \
 282   if(gs->envelope_status)                                                     \
 283   {                                                                           \
 284     u32 envelope_ticks = gs->envelope_ticks - 1;                              \
 285     envelope_volume = gs->envelope_volume;                                    \
 286                                                                               \
 287     if(envelope_ticks == 0)                                                   \
 288     {                                                                         \
 289       if(gs->envelope_direction)                                              \
 290       {                                                                       \
 291         if(envelope_volume != 15)                                             \
 292           envelope_volume = gs->envelope_volume + 1;                          \
 293       }                                                                       \
 294       else                                                                    \
 295       {                                                                       \
 296         if(envelope_volume != 0)                                              \
 297           envelope_volume = gs->envelope_volume - 1;                          \
 298       }                                                                       \
 299                                                                               \
 300       update_volume(envelope);                                                \
 301                                                                               \
 302       gs->envelope_volume = envelope_volume;                                  \
 303       gs->envelope_ticks = gs->envelope_initial_ticks;                        \
 304     }                                                                         \
 305     else                                                                      \
 306     {                                                                         \
 307       gs->envelope_ticks = envelope_ticks;                                    \
 308     }                                                                         \
 309   }                                                                           \
 310
 311 #define update_tone_noenvelope()                                              \
 312
 313 #define gbc_sound_synchronize()                                               \
 314   while(((gbc_sound_buffer_index - sound_buffer_base) % BUFFER_SIZE) >        \
 315    (audio_buffer_size * 2))                                                   \
 316   {                                                                           \
 317     SDL_CondWait(sound_cv, sound_mutex);                                      \
 318   }                                                                           \
 319
 320 #define update_tone_counters(envelope_op, sweep_op)                           \
 321   tick_counter += gbc_sound_tick_step;                                        \
 322   if(tick_counter > 0xFFFF)                                                   \
 323   {                                                                           \
 324     if(gs->length_status)                                                     \
 325     {                                                                         \
 326       u32 length_ticks = gs->length_ticks - 1;                                \
 327       gs->length_ticks = length_ticks;                                        \
 328                                                                               \
 329       if(length_ticks == 0)                                                   \
 330       {                                                                       \
 331         gs->active_flag = 0;                                                  \
 332         break;                                                                \
 333       }                                                                       \
 334     }                                                                         \
 335                                                                               \
 336     update_tone_##envelope_op();                                              \
 337     update_tone_##sweep_op();                                                 \
 338                                                                               \
 339     tick_counter &= 0xFFFF;                                                   \
 340   }                                                                           \
 341
 342 #define gbc_sound_render_sample_right()                                       \
 343   sound_buffer[buffer_index + 1] += (current_sample * volume_right) >> 22     \
 344
 345 #define gbc_sound_render_sample_left()                                        \
 346   sound_buffer[buffer_index] += (current_sample * volume_left) >> 22          \
 347
 348 #define gbc_sound_render_sample_both()                                        \
 349   gbc_sound_render_sample_right();                                            \
 350   gbc_sound_render_sample_left()                                              \
 351
 352 #define gbc_sound_render_samples(type, sample_length, envelope_op, sweep_op)  \
 353   for(i = 0; i < buffer_ticks; i++)                                           \
 354   {                                                                           \
 355     current_sample =                                                          \
 356      sample_data[fp16_16_to_u32(sample_index) % sample_length];               \
 357     gbc_sound_render_sample_##type();                                         \
 358                                                                               \
 359     sample_index += frequency_step;                                           \
 360     buffer_index = (buffer_index + 2) % BUFFER_SIZE;                          \
 361                                                                               \
 362     update_tone_counters(envelope_op, sweep_op);                              \
 363   }                                                                           \
 364
 365 #define gbc_noise_wrap_full 32767
 366
 367 #define gbc_noise_wrap_half 126
 368
 369 #define get_noise_sample_full()                                               \
 370   current_sample =                                                            \
 371    ((s32)(noise_table15[fp16_16_to_u32(sample_index) >> 5] <<                 \
 372    (fp16_16_to_u32(sample_index) & 0x1F)) >> 31) & 0x0F                       \
 373
 374 #define get_noise_sample_half()                                               \
 375   current_sample =                                                            \
 376    ((s32)(noise_table7[fp16_16_to_u32(sample_index) >> 5] <<                  \
 377    (fp16_16_to_u32(sample_index) & 0x1F)) >> 31) & 0x0F                       \
 378
 379 #define gbc_sound_render_noise(type, noise_type, envelope_op, sweep_op)       \
 380   for(i = 0; i < buffer_ticks; i++)                                           \
 381   {                                                                           \
 382     get_noise_sample_##noise_type();                                          \
 383     gbc_sound_render_sample_##type();                                         \
 384                                                                               \
 385     sample_index += frequency_step;                                           \
 386                                                                               \
 387     if(sample_index >= u32_to_fp16_16(gbc_noise_wrap_##noise_type))           \
 388       sample_index -= u32_to_fp16_16(gbc_noise_wrap_##noise_type);            \
 389                                                                               \
 390     buffer_index = (buffer_index + 2) % BUFFER_SIZE;                          \
 391     update_tone_counters(envelope_op, sweep_op);                              \
 392   }                                                                           \
 393
 394 #define gbc_sound_render_channel(type, sample_length, envelope_op, sweep_op)  \
 395   buffer_index = gbc_sound_buffer_index;                                      \
 396   sample_index = gs->sample_index;                                            \
 397   frequency_step = gs->frequency_step;                                        \
 398   tick_counter = gs->tick_counter;                                            \
 399                                                                               \
 400   update_volume(envelope_op);                                                 \
 401                                                                               \
 402   switch(gs->status)                                                          \
 403   {                                                                           \
 404     case GBC_SOUND_INACTIVE:                                                  \
 405       break;                                                                  \
 406                                                                               \
 407     case GBC_SOUND_LEFT:                                                      \
 408       gbc_sound_render_##type(left, sample_length, envelope_op, sweep_op);    \
 409       break;                                                                  \
 410                                                                               \
 411     case GBC_SOUND_RIGHT:                                                     \
 412       gbc_sound_render_##type(right, sample_length, envelope_op, sweep_op);   \
 413       break;                                                                  \
 414                                                                               \
 415     case GBC_SOUND_LEFTRIGHT:                                                 \
 416       gbc_sound_render_##type(both, sample_length, envelope_op, sweep_op);    \
 417       break;                                                                  \
 418   }                                                                           \
 419                                                                               \
 420   gs->sample_index = sample_index;                                            \
 421   gs->tick_counter = tick_counter;                                            \
 422
 423 #define gbc_sound_load_wave_ram(bank)                                         \
 424   wave_bank = wave_samples + (bank * 32);                                     \
 425   for(i = 0, i2 = 0; i < 16; i++, i2 += 2)                                    \
 426   {                                                                           \
 427     current_sample = wave_ram[i];                                             \
 428     wave_bank[i2] = (((current_sample >> 4) & 0x0F) - 8);                     \
 429     wave_bank[i2 + 1] = ((current_sample & 0x0F) - 8);                        \
 430   }                                                                           \
 431
 432 void synchronize_sound()
 433 {
 434   SDL_LockMutex(sound_mutex);
 435
 436   gbc_sound_synchronize();
 437
 438   SDL_UnlockMutex(sound_mutex);
 439 }
 440
 441 void update_gbc_sound(u32 cpu_ticks)
 442 {
 443   fixed16_16 buffer_ticks = float_to_fp16_16(((float)(cpu_ticks -
 444    gbc_sound_last_cpu_ticks) * sound_frequency) / 16777216.0);
 445   u32 i, i2;
 446   gbc_sound_struct *gs = gbc_sound_channel;
 447   fixed16_16 sample_index, frequency_step;
 448   fixed16_16 tick_counter;
 449   u32 buffer_index;
 450   s32 volume_left, volume_right;
 451   u32 envelope_volume;
 452   s32 current_sample;
 453   u32 sound_status = address16(io_registers, 0x84) & 0xFFF0;
 454   s8 *sample_data;
 455   s8 *wave_bank;
 456   u8 *wave_ram = ((u8 *)io_registers) + 0x90;
 457
 458   gbc_sound_partial_ticks += fp16_16_fractional_part(buffer_ticks);
 459   buffer_ticks = fp16_16_to_u32(buffer_ticks);
 460
 461   if(gbc_sound_partial_ticks > 0xFFFF)
 462   {
 463     buffer_ticks += 1;
 464     gbc_sound_partial_ticks &= 0xFFFF;
 465   }
 466
 467   SDL_LockMutex(sound_mutex);
 468   if(synchronize_flag)
 469   {
 470     if(((gbc_sound_buffer_index - sound_buffer_base) % BUFFER_SIZE) >
 471      (audio_buffer_size * 3 / 2))
 472     {
 473       while(((gbc_sound_buffer_index - sound_buffer_base) % BUFFER_SIZE) >
 474        (audio_buffer_size * 3 / 2))
 475       {
 476         SDL_CondWait(sound_cv, sound_mutex);
 477       }
 478
 479 #ifdef PSP_BUILD
 480       if(current_frameskip_type == auto_frameskip)
 481       {
 482         sceDisplayWaitVblankStart();
 483         real_frame_count = 0;
 484         virtual_frame_count = 0;
 485       }
 486 #else
 487       if(current_frameskip_type == auto_frameskip)
 488       {
 489 /*
 490         u64 current_ticks;
 491         u64 next_ticks;
 492         get_ticks_us(&current_ticks);
 493
 494         next_ticks = ((current_ticks + 16666) / 16667) * 16667;
 495         delay_us(next_ticks - current_ticks);
 496
 497         get_ticks_us(&frame_count_initial_timestamp);
 498 */
 499         /* prevent frameskip, or it will cause more audio,
 500          * then more waiting here, then frame skip again, ... */
 501         num_skipped_frames = 100;
 502       }
 503 #endif
 504
 505     }
 506   }
 507   if(sound_on == 1)
 508   {
 509     gs = gbc_sound_channel + 0;
 510     if(gs->active_flag)
 511     {
 512       sound_status |= 0x01;
 513       sample_data = gs->sample_data;
 514       envelope_volume = gs->envelope_volume;
 515       gbc_sound_render_channel(samples, 8, envelope, sweep);
 516     }
 517
 518     gs = gbc_sound_channel + 1;
 519     if(gs->active_flag)
 520     {
 521       sound_status |= 0x02;
 522       sample_data = gs->sample_data;
 523       envelope_volume = gs->envelope_volume;
 524       gbc_sound_render_channel(samples, 8, envelope, nosweep);
 525     }
 526
 527     gs = gbc_sound_channel + 2;
 528     if(gbc_sound_wave_update)
 529     {
 530       if(gs->wave_bank == 1)
 531       {
 532         gbc_sound_load_wave_ram(1);
 533       }
 534       else
 535       {
 536         gbc_sound_load_wave_ram(0);
 537       }
 538
 539       gbc_sound_wave_update = 0;
 540     }
 541
 542     if((gs->active_flag) && (gs->master_enable))
 543     {
 544       sound_status |= 0x04;
 545       sample_data = wave_samples;
 546       if(gs->wave_type == 0)
 547       {
 548         if(gs->wave_bank == 1)
 549           sample_data += 32;
 550
 551         gbc_sound_render_channel(samples, 32, noenvelope, nosweep);
 552       }
 553       else
 554       {
 555         gbc_sound_render_channel(samples, 64, noenvelope, nosweep);
 556       }
 557     }
 558
 559     gs = gbc_sound_channel + 3;
 560     if(gs->active_flag)
 561     {
 562       sound_status |= 0x08;
 563       envelope_volume = gs->envelope_volume;
 564
 565       if(gs->noise_type == 1)
 566       {
 567         gbc_sound_render_channel(noise, half, envelope, nosweep);
 568       }
 569       else
 570       {
 571         gbc_sound_render_channel(noise, full, envelope, nosweep);
 572       }
 573     }
 574   }
 575
 576   address16(io_registers, 0x84) = sound_status;
 577
 578   gbc_sound_last_cpu_ticks = cpu_ticks;
 579   gbc_sound_buffer_index =
 580    (gbc_sound_buffer_index + (buffer_ticks * 2)) % BUFFER_SIZE;
 581
 582   SDL_UnlockMutex(sound_mutex);
 583
 584   SDL_CondSignal(sound_cv);
 585 }
 586
 587 #define sound_copy_normal()                                                   \
 588   current_sample = source[i]                                                  \
 589
 590 #define sound_copy(source_offset, length, render_type)                        \
 591   _length = (length) / 2;                                                     \
 592   source = (s16 *)(sound_buffer + source_offset);                             \
 593   for(i = 0; i < _length; i++)                                                \
 594   {                                                                           \
 595     sound_copy_##render_type();                                               \
 596     if(current_sample > 2047)                                                 \
 597       current_sample = 2047;                                                  \
 598     if(current_sample < -2048)                                                \
 599       current_sample = -2048;                                                 \
 600                                                                               \
 601     stream_base[i] = current_sample << 4;                                     \
 602     source[i] = 0;                                                            \
 603   }                                                                           \
 604
 605 #define sound_copy_null(source_offset, length)                                \
 606   _length = (length) / 2;                                                     \
 607   source = (s16 *)(sound_buffer + source_offset);                             \
 608   for(i = 0; i < _length; i++)                                                \
 609   {                                                                           \
 610     stream_base[i] = 0;                                                       \
 611     source[i] = 0;                                                            \
 612   }                                                                           \
 613
 614
 615 void sound_callback(void *userdata, Uint8 *stream, int length)
 616 {
 617   u32 sample_length = length / 2;
 618   u32 _length;
 619   u32 i;
 620   s16 *stream_base = (s16 *)stream;
 621   s16 *source;
 622   s32 current_sample;
 623
 624   SDL_LockMutex(sound_mutex);
 625
 626   while(((gbc_sound_buffer_index - sound_buffer_base) % BUFFER_SIZE) <
 627    length && !sound_exit_flag)
 628   {
 629     SDL_CondWait(sound_cv, sound_mutex);
 630   }
 631
 632   if(global_enable_audio)
 633   {
 634     if((sound_buffer_base + sample_length) >= BUFFER_SIZE)
 635     {
 636       u32 partial_length = (BUFFER_SIZE - sound_buffer_base) * 2;
 637       sound_copy(sound_buffer_base, partial_length, normal);
 638       source = (s16 *)sound_buffer;
 639       sound_copy(0, length - partial_length, normal);
 640       sound_buffer_base = (length - partial_length) / 2;
 641     }
 642     else
 643     {
 644       sound_copy(sound_buffer_base, length, normal);
 645       sound_buffer_base += sample_length;
 646     }
 647   }
 648   else
 649   {
 650     if((sound_buffer_base + sample_length) >= BUFFER_SIZE)
 651     {
 652       u32 partial_length = (BUFFER_SIZE - sound_buffer_base) * 2;
 653       sound_copy_null(sound_buffer_base, partial_length);
 654       source = (s16 *)sound_buffer;
 655       sound_copy(0, length - partial_length, normal);
 656       sound_buffer_base = (length - partial_length) / 2;
 657     }
 658     else
 659     {
 660       sound_copy_null(sound_buffer_base, length);
 661       sound_buffer_base += sample_length;
 662     }
 663   }
 664
 665   SDL_CondSignal(sound_cv);
 666
 667   SDL_UnlockMutex(sound_mutex);
 668 }
 669
 670 // Special thanks to blarrg for the LSFR frequency used in Meridian, as posted
 671 // on the forum at http://meridian.overclocked.org:
 672 // http://meridian.overclocked.org/cgi-bin/wwwthreads/showpost.pl?Board=merid
 673 // angeneraldiscussion&Number=2069&page=0&view=expanded&mode=threaded&sb=4
 674 // Hope you don't mind me borrowing it ^_-
 675
 676 void init_noise_table(u32 *table, u32 period, u32 bit_length)
 677 {
 678   u32 shift_register = 0xFF;
 679   u32 mask = ~(1 << bit_length);
 680   s32 table_pos, bit_pos;
 681   u32 current_entry;
 682   u32 table_period = (period + 31) / 32;
 683
 684   // Bits are stored in reverse order so they can be more easily moved to
 685   // bit 31, for sign extended shift down.
 686
 687   for(table_pos = 0; table_pos < table_period; table_pos++)
 688   {
 689     current_entry = 0;
 690     for(bit_pos = 31; bit_pos >= 0; bit_pos--)
 691     {
 692       current_entry |= (shift_register & 0x01) << bit_pos;
 693
 694       shift_register =
 695        ((1 & (shift_register ^ (shift_register >> 1))) << bit_length) |
 696        ((shift_register >> 1) & mask);
 697     }
 698
 699     table[table_pos] = current_entry;
 700   }
 701 }
 702
 703 void reset_sound()
 704 {
 705   direct_sound_struct *ds = direct_sound_channel;
 706   gbc_sound_struct *gs = gbc_sound_channel;
 707   u32 i;
 708
 709   sound_on = 0;
 710   sound_buffer_base = 0;
 711   sound_last_cpu_ticks = 0;
 712   memset(sound_buffer, 0, audio_buffer_size);
 713
 714   for(i = 0; i < 2; i++, ds++)
 715   {
 716     ds->buffer_index = 0;
 717     ds->status = DIRECT_SOUND_INACTIVE;
 718     ds->fifo_top = 0;
 719     ds->fifo_base = 0;
 720     ds->fifo_fractional = 0;
 721     ds->last_cpu_ticks = 0;
 722     memset(ds->fifo, 0, 32);
 723   }
 724
 725   gbc_sound_buffer_index = 0;
 726   gbc_sound_last_cpu_ticks = 0;
 727   gbc_sound_partial_ticks = 0;
 728
 729   gbc_sound_master_volume_left = 0;
 730   gbc_sound_master_volume_right = 0;
 731   gbc_sound_master_volume = 0;
 732   memset(wave_samples, 0, 64);
 733
 734   for(i = 0; i < 4; i++, gs++)
 735   {
 736     gs->status = GBC_SOUND_INACTIVE;
 737     gs->sample_data = square_pattern_duty[2];
 738     gs->active_flag = 0;
 739   }
 740 }
 741
 742 void sound_exit()
 743 {
 744   gbc_sound_buffer_index =
 745    (sound_buffer_base + audio_buffer_size) % BUFFER_SIZE;
 746   SDL_PauseAudio(1);
 747   sound_exit_flag = 1;
 748   SDL_CondSignal(sound_cv);
 749   SDL_CloseAudio();
 750 }
 751
 752 void init_sound()
 753 {
 754 #ifdef PSP_BUILD
 755   audio_buffer_size = (audio_buffer_size_number * 1024) + 3072;
 756 #else
 757   audio_buffer_size = 16 << audio_buffer_size_number;
 758 //  audio_buffer_size = 16384;
 759 #endif
 760
 761   SDL_AudioSpec desired_spec =
 762   {
 763     sound_frequency,
 764     AUDIO_S16,
 765     2,
 766     0,
 767     audio_buffer_size / 4,
 768     0,
 769     0,
 770     sound_callback,
 771     NULL
 772   };
 773
 774   gbc_sound_tick_step =
 775    float_to_fp16_16(256.0 / sound_frequency);
 776
 777   init_noise_table(noise_table15, 32767, 14);
 778   init_noise_table(noise_table7, 127, 6);
 779
 780   reset_sound();
 781
 782   sound_mutex = SDL_CreateMutex();
 783   sound_cv = SDL_CreateCond();
 784
 785   SDL_OpenAudio(&desired_spec, &sound_settings);
 786   sound_frequency = sound_settings.freq;
 787   audio_buffer_size = sound_settings.size;
 788   u32 i = audio_buffer_size / 16;
 789   for (audio_buffer_size_number = 0; i && (i & 1) == 0; i >>= 1)
 790     audio_buffer_size_number++;
 791 #ifndef PSP_BUILD
 792   printf("audio: freq %d, size %d\n", sound_frequency, audio_buffer_size);
 793 #endif
 794
 795   SDL_PauseAudio(0);
 796 }
 797
 798 #define sound_savestate_builder(type)                                       \
 799 void sound_##type##_savestate(file_tag_type savestate_file)                 \
 800 {                                                                           \
 801   file_##type##_variable(savestate_file, sound_on);                         \
 802   file_##type##_variable(savestate_file, sound_buffer_base);                \
 803   file_##type##_variable(savestate_file, sound_last_cpu_ticks);             \
 804   file_##type##_variable(savestate_file, gbc_sound_buffer_index);           \
 805   file_##type##_variable(savestate_file, gbc_sound_last_cpu_ticks);         \
 806   file_##type##_variable(savestate_file, gbc_sound_partial_ticks);          \
 807   file_##type##_variable(savestate_file, gbc_sound_master_volume_left);     \
 808   file_##type##_variable(savestate_file, gbc_sound_master_volume_right);    \
 809   file_##type##_variable(savestate_file, gbc_sound_master_volume);          \
 810   file_##type##_array(savestate_file, wave_samples);                        \
 811   file_##type##_array(savestate_file, direct_sound_channel);                \
 812   file_##type##_array(savestate_file, gbc_sound_channel);                   \
 813 }                                                                           \
 814
 815 sound_savestate_builder(read);
 816 sound_savestate_builder(write_mem);
 817