src/lib/midi.c

   1 /* midi.c
   2  *
   3  * Adlib OPL2/OPL3 FM synthesizer chipset test program.
   4  * Play MIDI file using the OPLx synthesizer (well, poorly anyway)
   5  * (C) 2010-2012 Jonathan Campbell.
   6  * Hackipedia DOS library.
   7  *
   8  * This code is licensed under the LGPL.
   9  * <insert LGPL legal text here>
  10  *
  11  * Compiles for intended target environments:
  12  *   - MS-DOS [pure DOS mode, or Windows or OS/2 DOS Box]
  13  */
  14
  15 #include "src/lib/midi.h"
  16
  17 static unsigned int             midi_trk_count=0;
  18
  19 /* MIDI params. Nobody ever said it was a straightforward standard!
  20  * NTS: These are for reading reference. Internally we convert everything to 100Hz time base. */
  21 static unsigned int ticks_per_quarter_note=0;   /* "Ticks per beat" */
  22
  23 #if TARGET_MSDOS == 16 && (defined(__LARGE__) || defined(__COMPACT__))
  24 static inline unsigned long farptr2phys(unsigned char far *p) { /* take 16:16 pointer convert to physical memory address */
  25         return ((unsigned long)FP_SEG(p) << 4UL) + ((unsigned long)FP_OFF(p));
  26 }
  27 #endif
  28
  29 static inline unsigned char midi_trk_read(struct midi_track *t) {
  30         unsigned char c;
  31
  32         /* NTS: 16-bit large/compact builds MUST compare pointers as unsigned long to compare FAR pointers correctly! */
  33         if (t->read == NULL || (unsigned long)t->read >= (unsigned long)t->fence) {
  34                 t->eof = 1;
  35                 return 0xFF;
  36         }
  37
  38         c = *(t->read);
  39 #if TARGET_MSDOS == 16 && (defined(__LARGE__) || defined(__COMPACT__))
  40         if (FP_OFF(t->read) >= 0xF) /* 16:16 far pointer aware (NTS: Programs reassigning this pointer MUST normalize the FAR pointer) */
  41                 t->read = MK_FP(FP_SEG(t->read)+0x1,0);
  42         else
  43                 t->read++;
  44 #else
  45         t->read++;
  46 #endif
  47         return c;
  48 }
  49
  50 void midi_trk_end(struct midi_track *t) {
  51         t->wait = ~0UL;
  52         t->read = t->fence;
  53 }
  54
  55 void midi_trk_skip(struct midi_track *t,unsigned long len) {
  56         unsigned long rem;
  57
  58         /* NTS: 16-bit large/compact builds MUST compare pointers as unsigned long to compare FAR pointers correctly! */
  59         if (t->read == NULL || (unsigned long)t->read >= (unsigned long)t->fence)
  60                 return;
  61
  62         if (len > 0xFFF0UL) {
  63                 midi_trk_end(t);
  64                 return;
  65         }
  66 #if TARGET_MSDOS == 16 && (defined(__LARGE__) || defined(__COMPACT__))
  67         {
  68                 unsigned long tt;
  69
  70                 tt = farptr2phys(t->read);
  71                 rem = farptr2phys(t->fence) - tt;
  72                 if (rem > len) rem = len;
  73                 tt += rem;
  74                 t->read = MK_FP(tt>>4,tt&0xF);
  75         }
  76 #else
  77         rem = (unsigned long)(t->fence - t->read);
  78         if (len > rem) len = rem;
  79         t->read += len;
  80 #endif
  81 }
  82
  83 static const uint32_t midikeys_freqs[0x80] = {
  84         0x00082d01,     /* key 0 = 8.17579891564371Hz */
  85         0x0008a976,     /* key 1 = 8.66195721802725Hz */
  86         0x00092d51,     /* key 2 = 9.17702399741899Hz */
  87         0x0009b904,     /* key 3 = 9.72271824131503Hz */
  88         0x000a4d05,     /* key 4 = 10.3008611535272Hz */
  89         0x000ae9d3,     /* key 5 = 10.9133822322814Hz */
  90         0x000b8ff4,     /* key 6 = 11.5623257097386Hz */
  91         0x000c3ff6,     /* key 7 = 12.2498573744297Hz */
  92         0x000cfa70,     /* key 8 = 12.9782717993733Hz */
  93         0x000dc000,     /* key 9 = 13.75Hz */
  94         0x000e914f,     /* key 10 = 14.5676175474403Hz */
  95         0x000f6f11,     /* key 11 = 15.4338531642539Hz */
  96         0x00105a02,     /* key 12 = 16.3515978312874Hz */
  97         0x001152ec,     /* key 13 = 17.3239144360545Hz */
  98         0x00125aa2,     /* key 14 = 18.354047994838Hz */
  99         0x00137208,     /* key 15 = 19.4454364826301Hz */
 100         0x00149a0a,     /* key 16 = 20.6017223070544Hz */
 101         0x0015d3a6,     /* key 17 = 21.8267644645627Hz */
 102         0x00171fe9,     /* key 18 = 23.1246514194771Hz */
 103         0x00187fed,     /* key 19 = 24.4997147488593Hz */
 104         0x0019f4e0,     /* key 20 = 25.9565435987466Hz */
 105         0x001b8000,     /* key 21 = 27.5Hz */
 106         0x001d229e,     /* key 22 = 29.1352350948806Hz */
 107         0x001ede22,     /* key 23 = 30.8677063285078Hz */
 108         0x0020b404,     /* key 24 = 32.7031956625748Hz */
 109         0x0022a5d8,     /* key 25 = 34.647828872109Hz */
 110         0x0024b545,     /* key 26 = 36.7080959896759Hz */
 111         0x0026e410,     /* key 27 = 38.8908729652601Hz */
 112         0x00293414,     /* key 28 = 41.2034446141087Hz */
 113         0x002ba74d,     /* key 29 = 43.6535289291255Hz */
 114         0x002e3fd2,     /* key 30 = 46.2493028389543Hz */
 115         0x0030ffda,     /* key 31 = 48.9994294977187Hz */
 116         0x0033e9c0,     /* key 32 = 51.9130871974931Hz */
 117         0x00370000,     /* key 33 = 55Hz */
 118         0x003a453d,     /* key 34 = 58.2704701897612Hz */
 119         0x003dbc44,     /* key 35 = 61.7354126570155Hz */
 120         0x00416809,     /* key 36 = 65.4063913251497Hz */
 121         0x00454bb0,     /* key 37 = 69.295657744218Hz */
 122         0x00496a8b,     /* key 38 = 73.4161919793519Hz */
 123         0x004dc820,     /* key 39 = 77.7817459305202Hz */
 124         0x00526829,     /* key 40 = 82.4068892282175Hz */
 125         0x00574e9b,     /* key 41 = 87.307057858251Hz */
 126         0x005c7fa4,     /* key 42 = 92.4986056779086Hz */
 127         0x0061ffb5,     /* key 43 = 97.9988589954373Hz */
 128         0x0067d380,     /* key 44 = 103.826174394986Hz */
 129         0x006e0000,     /* key 45 = 110Hz */
 130         0x00748a7b,     /* key 46 = 116.540940379522Hz */
 131         0x007b7888,     /* key 47 = 123.470825314031Hz */
 132         0x0082d012,     /* key 48 = 130.812782650299Hz */
 133         0x008a9760,     /* key 49 = 138.591315488436Hz */
 134         0x0092d517,     /* key 50 = 146.832383958704Hz */
 135         0x009b9041,     /* key 51 = 155.56349186104Hz */
 136         0x00a4d053,     /* key 52 = 164.813778456435Hz */
 137         0x00ae9d36,     /* key 53 = 174.614115716502Hz */
 138         0x00b8ff49,     /* key 54 = 184.997211355817Hz */
 139         0x00c3ff6a,     /* key 55 = 195.997717990875Hz */
 140         0x00cfa700,     /* key 56 = 207.652348789973Hz */
 141         0x00dc0000,     /* key 57 = 220Hz */
 142         0x00e914f6,     /* key 58 = 233.081880759045Hz */
 143         0x00f6f110,     /* key 59 = 246.941650628062Hz */
 144         0x0105a025,     /* key 60 = 261.625565300599Hz */
 145         0x01152ec0,     /* key 61 = 277.182630976872Hz */
 146         0x0125aa2e,     /* key 62 = 293.664767917408Hz */
 147         0x01372082,     /* key 63 = 311.126983722081Hz */
 148         0x0149a0a7,     /* key 64 = 329.62755691287Hz */
 149         0x015d3a6d,     /* key 65 = 349.228231433004Hz */
 150         0x0171fe92,     /* key 66 = 369.994422711634Hz */
 151         0x0187fed4,     /* key 67 = 391.995435981749Hz */
 152         0x019f4e00,     /* key 68 = 415.304697579945Hz */
 153         0x01b80000,     /* key 69 = 440Hz */
 154         0x01d229ec,     /* key 70 = 466.16376151809Hz */
 155         0x01ede220,     /* key 71 = 493.883301256124Hz */
 156         0x020b404a,     /* key 72 = 523.251130601197Hz */
 157         0x022a5d81,     /* key 73 = 554.365261953744Hz */
 158         0x024b545c,     /* key 74 = 587.329535834815Hz */
 159         0x026e4104,     /* key 75 = 622.253967444162Hz */
 160         0x0293414f,     /* key 76 = 659.25511382574Hz */
 161         0x02ba74da,     /* key 77 = 698.456462866008Hz */
 162         0x02e3fd24,     /* key 78 = 739.988845423269Hz */
 163         0x030ffda9,     /* key 79 = 783.990871963499Hz */
 164         0x033e9c01,     /* key 80 = 830.60939515989Hz */
 165         0x03700000,     /* key 81 = 880Hz */
 166         0x03a453d8,     /* key 82 = 932.32752303618Hz */
 167         0x03dbc440,     /* key 83 = 987.766602512248Hz */
 168         0x04168094,     /* key 84 = 1046.50226120239Hz */
 169         0x0454bb03,     /* key 85 = 1108.73052390749Hz */
 170         0x0496a8b8,     /* key 86 = 1174.65907166963Hz */
 171         0x04dc8208,     /* key 87 = 1244.50793488832Hz */
 172         0x0526829e,     /* key 88 = 1318.51022765148Hz */
 173         0x0574e9b5,     /* key 89 = 1396.91292573202Hz */
 174         0x05c7fa49,     /* key 90 = 1479.97769084654Hz */
 175         0x061ffb53,     /* key 91 = 1567.981743927Hz */
 176         0x067d3802,     /* key 92 = 1661.21879031978Hz */
 177         0x06e00000,     /* key 93 = 1760Hz */
 178         0x0748a7b1,     /* key 94 = 1864.65504607236Hz */
 179         0x07b78880,     /* key 95 = 1975.5332050245Hz */
 180         0x082d0128,     /* key 96 = 2093.00452240479Hz */
 181         0x08a97607,     /* key 97 = 2217.46104781498Hz */
 182         0x092d5171,     /* key 98 = 2349.31814333926Hz */
 183         0x09b90410,     /* key 99 = 2489.01586977665Hz */
 184         0x0a4d053c,     /* key 100 = 2637.02045530296Hz */
 185         0x0ae9d36b,     /* key 101 = 2793.82585146403Hz */
 186         0x0b8ff493,     /* key 102 = 2959.95538169308Hz */
 187         0x0c3ff6a7,     /* key 103 = 3135.96348785399Hz */
 188         0x0cfa7005,     /* key 104 = 3322.43758063956Hz */
 189         0x0dc00000,     /* key 105 = 3520Hz */
 190         0x0e914f62,     /* key 106 = 3729.31009214472Hz */
 191         0x0f6f1100,     /* key 107 = 3951.06641004899Hz */
 192         0x105a0250,     /* key 108 = 4186.00904480958Hz */
 193         0x1152ec0e,     /* key 109 = 4434.92209562995Hz */
 194         0x125aa2e3,     /* key 110 = 4698.63628667852Hz */
 195         0x13720820,     /* key 111 = 4978.03173955329Hz */
 196         0x149a0a79,     /* key 112 = 5274.04091060592Hz */
 197         0x15d3a6d6,     /* key 113 = 5587.65170292806Hz */
 198         0x171fe927,     /* key 114 = 5919.91076338615Hz */
 199         0x187fed4e,     /* key 115 = 6271.92697570799Hz */
 200         0x19f4e00a,     /* key 116 = 6644.87516127912Hz */
 201         0x1b800000,     /* key 117 = 7040Hz */
 202         0x1d229ec4,     /* key 118 = 7458.62018428944Hz */
 203         0x1ede2200,     /* key 119 = 7902.13282009799Hz */
 204         0x20b404a1,     /* key 120 = 8372.01808961916Hz */
 205         0x22a5d81c,     /* key 121 = 8869.84419125991Hz */
 206         0x24b545c7,     /* key 122 = 9397.27257335704Hz */
 207         0x26e41040,     /* key 123 = 9956.06347910659Hz */
 208         0x293414f2,     /* key 124 = 10548.0818212118Hz */
 209         0x2ba74dac,     /* key 125 = 11175.3034058561Hz */
 210         0x2e3fd24f,     /* key 126 = 11839.8215267723Hz */
 211         0x30ffda9c      /* key 127 = 12543.853951416Hz */
 212 };
 213
 214 static uint32_t midi_note_freq(struct midi_channel *ch,unsigned char key) {
 215         return midikeys_freqs[key&0x7F];
 216 }
 217
 218 static struct midi_note *get_fm_note(struct midi_track *t,struct midi_channel *ch,unsigned char key,unsigned char do_alloc) {
 219         unsigned int tch = (unsigned int)(t - midi_trk); /* pointer math */
 220         unsigned int ach = (unsigned int)(ch - midi_ch); /* pointer math */
 221         unsigned int i,freen=~0;
 222
 223         for (i=0;i < ADLIB_FM_VOICES;i++) {
 224                 if (midi_notes[i].busy) {
 225                         if (midi_notes[i].note_channel == ach && midi_notes[i].note_track == tch && midi_notes[i].note_number == key)
 226                                 return &midi_notes[i];
 227                 }
 228                 else {
 229                         if (freen == ~0) freen = i;
 230                 }
 231         }
 232
 233         if (do_alloc && freen != ~0) return &midi_notes[freen];
 234         return NULL;
 235 }
 236
 237 static void drop_fm_note(struct midi_channel *ch,unsigned char key) {
 238         unsigned int ach = (unsigned int)(ch - midi_ch); /* pointer math */
 239         unsigned int i;
 240
 241         for (i=0;i < ADLIB_FM_VOICES;i++) {
 242                 if (midi_notes[i].busy && midi_notes[i].note_channel == ach) {
 243                         midi_notes[i].busy = 0;
 244                         break;
 245                 }
 246         }
 247 }
 248
 249 static inline void on_key_aftertouch(struct midi_track *t,struct midi_channel *ch,unsigned char key,unsigned char vel) {
 250         struct midi_note *note = get_fm_note(t,ch,key,/*do_alloc*/0);
 251         uint32_t freq = midi_note_freq(ch,key);
 252         unsigned int ach;
 253
 254         if (note == NULL) return;
 255
 256         note->busy = 1;
 257         note->note_number = key;
 258         note->note_velocity = vel;
 259         note->note_track = (unsigned int)(t - midi_trk);
 260         note->note_channel = (unsigned int)(ch - midi_ch);
 261         ach = (unsigned int)(note - midi_notes); /* which FM channel? */
 262         adlib_freq_to_fm_op(&adlib_fm[ach].mod,(double)freq / 65536);
 263         adlib_fm[ach].mod.attack_rate = vel >> 3; /* 0-127 to 0-15 */
 264         adlib_fm[ach].mod.sustain_level = vel >> 3;
 265         adlib_fm[ach].mod.key_on = 1;
 266         adlib_update_groupA0(ach,&adlib_fm[ach]);
 267 }
 268
 269 static inline void on_key_on(struct midi_track *t,struct midi_channel *ch,unsigned char key,unsigned char vel) {
 270         struct midi_note *note = get_fm_note(t,ch,key,/*do_alloc*/1);
 271         uint32_t freq = midi_note_freq(ch,key);
 272         unsigned int ach;
 273
 274         /* HACK: Ignore percussion */
 275         if ((ch->program >= 8 && ch->program <= 15)/*Chromatic percussion*/ ||
 276                 (ch->program >= 112 && ch->program <= 119)/*Percussive*/ ||
 277                 ch == &midi_ch[9]/*MIDI channel 10 (DAMN YOU 1-BASED COUNTING)*/)
 278                 return;
 279
 280         if (note == NULL) {
 281                 /* then we'll have to knock one off to make room */
 282                 drop_fm_note(ch,key);
 283                 note = get_fm_note(t,ch,key,1);
 284                 if (note == NULL) return;
 285         }
 286
 287         note->busy = 1;
 288         note->note_number = key;
 289         note->note_velocity = vel;
 290         note->note_track = (unsigned int)(t - midi_trk);
 291         note->note_channel = (unsigned int)(ch - midi_ch);
 292         ach = (unsigned int)(note - midi_notes); /* which FM channel? */
 293         adlib_freq_to_fm_op(&adlib_fm[ach].mod,(double)freq / 65536);
 294         adlib_fm[ach].mod.attack_rate = vel >> 3; /* 0-127 to 0-15 */
 295         adlib_fm[ach].mod.sustain_level = vel >> 3;
 296         adlib_fm[ach].mod.key_on = 1;
 297         adlib_update_groupA0(ach,&adlib_fm[ach]);
 298 }
 299
 300 static inline void on_key_off(struct midi_track *t,struct midi_channel *ch,unsigned char key,unsigned char vel) {
 301         struct midi_note *note = get_fm_note(t,ch,key,/*do_alloc*/0);
 302         uint32_t freq = midi_note_freq(ch,key);
 303         unsigned int ach;
 304
 305         if (note == NULL) return;
 306
 307         note->busy = 0;
 308         ach = (unsigned int)(note - midi_notes); /* which FM channel? */
 309         adlib_freq_to_fm_op(&adlib_fm[ach].mod,(double)freq / 65536);
 310         adlib_fm[ach].mod.attack_rate = vel >> 3; /* 0-127 to 0-15 */
 311         adlib_fm[ach].mod.sustain_level = vel >> 3;
 312         adlib_fm[ach].mod.key_on = 0;
 313         adlib_update_groupA0(ach,&adlib_fm[ach]);
 314 }
 315
 316 static inline void on_control_change(struct midi_track *t,struct midi_channel *ch,unsigned char num,unsigned char val) {
 317 }
 318
 319 static inline void on_program_change(struct midi_track *t,struct midi_channel *ch,unsigned char inst) {
 320         ch->program = inst;
 321 }
 322
 323 static inline void on_channel_aftertouch(struct midi_track *t,struct midi_channel *ch,unsigned char velocity) {
 324 }
 325
 326 static inline void on_pitch_bend(struct midi_track *t,struct midi_channel *ch,int bend/*-8192 to 8192*/) {
 327 }
 328
 329 unsigned long midi_trk_read_delta(struct midi_track *t) {
 330         unsigned long tc = 0;
 331         unsigned char c = 0,b;
 332
 333         /* NTS: 16-bit large/compact builds MUST compare pointers as unsigned long to compare FAR pointers correctly! */
 334         if (t->read == NULL || (unsigned long)t->read >= (unsigned long)t->fence)
 335                 return tc;
 336
 337         while (c < 4) {
 338                 b = midi_trk_read(t);
 339                 tc = (tc << 7UL) + (unsigned long)(b&0x7F);
 340                 if (!(b&0x80)) break;
 341                 c++;
 342         }
 343
 344         return tc;
 345 }
 346
 347 void midi_tick_track(unsigned int i) {
 348         struct midi_track *t = midi_trk + i;
 349         struct midi_channel *ch;
 350         unsigned char b,c,d;
 351         int cnt=0;
 352
 353         /* NTS: 16-bit large/compact builds MUST compare pointers as unsigned long to compare FAR pointers correctly! */
 354         if (t->read == NULL || (unsigned long)t->read >= (unsigned long)t->fence) {
 355                 t->eof = 1;
 356                 return;
 357         }
 358
 359         t->us_tick_cnt_mtpq += 10000UL * (unsigned long)ticks_per_quarter_note;
 360         while (t->us_tick_cnt_mtpq >= t->us_per_quarter_note) {
 361                 t->us_tick_cnt_mtpq -= t->us_per_quarter_note;
 362                 cnt++;
 363
 364                 while (t->wait == 0) {
 365                         if ((unsigned long)t->read >= (unsigned long)t->fence) {
 366                                 t->eof = 1;
 367                                 break;
 368                         }
 369
 370                         /* read pointer should be pointing at MIDI event bytes, just after the time delay */
 371                         b = midi_trk_read(t);
 372                         if (b&0x80) {
 373                                 if (b < 0xF8) {
 374                                         if (b >= 0xF0)
 375                                                 t->last_status = 0;
 376                                         else
 377                                                 t->last_status = b;
 378                                 }
 379                                 if (b != 0x00 && ((b&0xF8) != 0xF0))
 380                                         c = midi_trk_read(t);
 381                         }
 382                         else {
 383                                 /* blegh. last status */
 384                                 c = b;
 385                                 b = t->last_status;
 386                         }
 387                         switch (b>>4) {
 388                                 case 0x8: { /* note off */
 389                                         d = midi_trk_read(t);
 390                                         ch = midi_ch + (b&0xF); /* c=key d=velocity */
 391                                         on_key_off(t,ch,c,d);
 392                                         } break;
 393                                 case 0x9: { /* note on */
 394                                         d = midi_trk_read(t);
 395                                         ch = midi_ch + (b&0xF); /* c=key d=velocity */
 396                                         if (d != 0) on_key_on(t,ch,c,d); /* "A Note On with a velocity of 0 is actually a note off" Bleh, really? */
 397                                         else on_key_off(t,ch,c,d);
 398                                         } break;
 399                                 case 0xA: { /* polyphonic aftertouch */
 400                                         d = midi_trk_read(t);
 401                                         ch = midi_ch + (b&0xF); /* c=key d=velocity */
 402                                         on_key_aftertouch(t,ch,c,d);
 403                                         } break;
 404                                 case 0xB: { /* control change */
 405                                         d = midi_trk_read(t);
 406                                         ch = midi_ch + (b&0xF); /* c=key d=velocity */
 407                                         on_control_change(t,ch,c,d);
 408                                         } break;
 409                                 case 0xC: { /* program change */
 410                                         on_program_change(t,ch,c); /* c=instrument d=not used */
 411                                         } break;
 412                                 case 0xD: { /* channel aftertouch */
 413                                         on_channel_aftertouch(t,ch,c); /* c=velocity d=not used */
 414                                         } break;
 415                                 case 0xE: { /* pitch bend */
 416                                         d = midi_trk_read(t);
 417                                         on_pitch_bend(t,ch,((c&0x7F)|((d&0x7F)<<7))-8192); /* c=LSB d=MSB */
 418                                         } break;
 419                                 case 0xF: { /* event */
 420                                         if (b == 0xFF) {
 421                                                 if (c == 0x7F) { /* c=type d=len */
 422                                                         unsigned long len = midi_trk_read_delta(t);
 423 //                                                      fprintf(stderr,"Type 0x7F len=%lu %p/%p/%p\n",len,t->raw,t->read,t->fence);
 424                                                         if (len < 512UL) {
 425                                                                 /* unknown */
 426                                                                 midi_trk_skip(t,len);
 427                                                         }
 428                                                         else {
 429                                                                 midi_trk_end(t);
 430                                                         }
 431                                                 }
 432                                                 else if (c < 0x7F) {
 433                                                         d = midi_trk_read(t);
 434
 435                                                         if (c == 0x51 && d >= 3) {
 436                                                                 d -= 3;
 437                                                                 t->us_per_quarter_note = ((unsigned long)midi_trk_read(t)<<16UL)+
 438                                                                         ((unsigned long)midi_trk_read(t)<<8UL)+
 439                                                                         ((unsigned long)midi_trk_read(t)<<0UL);
 440
 441                                                                 if (1/*TODO: If format 0 or format 1*/) {
 442                                                                         /* Ugh. Unless format 2, the tempo applies to all tracks */
 443                                                                         int j;
 444
 445                                                                         for (j=0;j < midi_trk_count;j++) {
 446                                                                                 if (j != i) midi_trk[j].us_per_quarter_note =
 447                                                                                         t->us_per_quarter_note;
 448                                                                         }
 449                                                                 }
 450                                                         }
 451                                                         else {
 452 //                                                              fprintf(stderr,"Type 0x%02x len=%lu %p/%p/%p\n",c,d,t->raw,t->read,t->fence);
 453                                                         }
 454
 455                                                         midi_trk_skip(t,d);
 456                                                 }
 457                                                 else {
 458                                                         fprintf(stderr,"t=%u Unknown MIDI f message 0x%02x 0x%02x %p/%p/%p\n",i,b,c,t->raw,t->read,t->fence);
 459                                                 }
 460                                         }
 461                                         else {
 462                                                 unsigned long len = midi_trk_read_delta(t);
 463 //                                              fprintf(stderr,"Sysex len=%lu %p/%p/%p\n",len,t->raw,t->read,t->fence);
 464                                                 midi_trk_skip(t,len);
 465                                         }
 466                                         } break;
 467                                 default:
 468                                         if (b != 0x00) {
 469                                                 fprintf(stderr,"t=%u Unknown MIDI message 0x%02x at %p/%p/%p\n",i,b,t->raw,t->read,t->fence);
 470                                                 midi_trk_end(t);
 471                                         }
 472                                         break;
 473                         };
 474
 475                         /* and then read the next event */
 476                         t->wait = midi_trk_read_delta(t);
 477                 }
 478                 if (t->wait != 0) {
 479                         t->wait--;
 480                 }
 481         }
 482 }
 483
 484 void adlib_shut_up();
 485 void midi_reset_tracks();
 486 void midi_reset_channels();
 487
 488 void midi_tick() {
 489         if (midi_playing) {
 490                 unsigned int i;
 491                 int eof=0;
 492
 493                 for (i=0;i < midi_trk_count;i++) {
 494                         midi_tick_track(i);
 495                         eof += midi_trk[i].eof?1:0;
 496                 }
 497
 498                 if (eof >= midi_trk_count) {
 499                         adlib_shut_up();
 500                         midi_reset_tracks();
 501                         midi_reset_channels();
 502                 }
 503         }
 504 }
 505
 506 /* WARNING: subroutine call in interrupt handler. make sure you compile with -zu flag for large/compact memory models */
 507 void interrupt irq0() {
 508 //      midi_tick();
 509         irq0_ticks++;
 510         if ((irq0_cnt += irq0_add) >= irq0_max) {
 511                 irq0_cnt -= irq0_max;
 512                 old_irq0();
 513         }
 514         else {
 515                 p8259_OCW2(0,P8259_OCW2_NON_SPECIFIC_EOI);
 516         }
 517 }
 518
 519 void adlib_shut_up() {
 520         int i;
 521
 522         memset(adlib_fm,0,sizeof(adlib_fm));
 523         memset(&adlib_reg_bd,0,sizeof(adlib_reg_bd));
 524         for (i=0;i < adlib_fm_voices;i++) {
 525                 struct adlib_fm_operator *f;
 526                 f = &adlib_fm[i].mod;
 527                 f->ch_a = f->ch_b = f->ch_c = f->ch_d = 1;
 528                 f = &adlib_fm[i].car;
 529                 f->ch_a = f->ch_b = f->ch_c = f->ch_d = 1;
 530         }
 531
 532         for (i=0;i < adlib_fm_voices;i++) {
 533                 struct adlib_fm_operator *f;
 534
 535                 midi_notes[i].busy = 0;
 536                 midi_notes[i].note_channel = 0;
 537
 538                 f = &adlib_fm[i].mod;
 539                 f->mod_multiple = 1;
 540                 f->total_level = 63 - 16;
 541                 f->attack_rate = 15;
 542                 f->decay_rate = 4;
 543                 f->sustain_level = 0;
 544                 f->release_rate = 8;
 545                 f->f_number = 400;
 546                 f->sustain = 1;
 547                 f->octave = 4;
 548                 f->key_on = 0;
 549
 550                 f = &adlib_fm[i].car;
 551                 f->mod_multiple = 1;
 552                 f->total_level = 63 - 16;
 553                 f->attack_rate = 15;
 554                 f->decay_rate = 4;
 555                 f->sustain_level = 0;
 556                 f->release_rate = 8;
 557                 f->f_number = 0;
 558                 f->sustain = 1;
 559                 f->octave = 0;
 560                 f->key_on = 0;
 561         }
 562
 563         adlib_apply_all();
 564 }
 565
 566 void midi_reset_track(unsigned int i) {
 567         struct midi_track *t;
 568
 569         if (i >= MIDI_MAX_TRACKS) return;
 570         t = &midi_trk[i];
 571         t->eof = 0;
 572         t->last_status = 0;
 573         t->us_tick_cnt_mtpq = 0;
 574         t->us_per_quarter_note = (60000000UL / 120UL); /* 120BPM */
 575         t->read = midi_trk[i].raw;
 576         t->wait = midi_trk_read_delta(t); /* and then the read pointer will point at the MIDI event when wait counts down */
 577 }
 578
 579 void midi_reset_tracks() {
 580         int i;
 581
 582         for (i=0;i < midi_trk_count;i++)
 583                 midi_reset_track(i);
 584 }
 585
 586 void midi_reset_channels() {
 587         int i;
 588
 589         for (i=0;i < MIDI_MAX_CHANNELS;i++) {
 590                 midi_ch[i].program = 0;
 591         }
 592 }
 593
 594 int load_midi_file(const char *path) {
 595         unsigned char tmp[256];
 596         unsigned int tracks=0;
 597         unsigned int tracki=0;
 598         int fd;
 599
 600         fd = open(path,O_RDONLY|O_BINARY);
 601         if (fd < 0) {
 602                 printf("Failed to load file %s\n",path);
 603                 return 0;
 604         }
 605
 606         ticks_per_quarter_note = 0;
 607         while (read(fd,tmp,8) == 8) {
 608                 uint32_t sz;
 609
 610                 sz =    ((uint32_t)tmp[4] << (uint32_t)24) |
 611                         ((uint32_t)tmp[5] << (uint32_t)16) |
 612                         ((uint32_t)tmp[6] << (uint32_t)8) |
 613                         ((uint32_t)tmp[7] << (uint32_t)0);
 614                 if (!memcmp(tmp,"MThd",4)) {
 615                         unsigned short t,tdiv;
 616
 617                         if (sz < 6 || sz > 255) {
 618                                 fprintf(stderr,"Invalid MThd size %lu\n",(unsigned long)sz);
 619                                 goto err;
 620                         }
 621                         if (read(fd,tmp,(int)sz) != (int)sz) {
 622                                 fprintf(stderr,"MThd read error\n");
 623                                 goto err;
 624                         }
 625
 626                         /* byte 0-1 = format type (0,1 or 2) */
 627                         /* byte 2-3 = number of tracks */
 628                         /* byte 4-5 = time divison */
 629                         t = tmp[1] | (tmp[0] << 8);
 630                         if (t > 1) {
 631                                 fprintf(stderr,"MThd type %u not supported\n",t);
 632                                 goto err; /* we only take type 0 or 1, don't support 2 */
 633                         }
 634                         tracks = tmp[3] | (tmp[2] << 8);
 635                         if (tracks > MIDI_MAX_TRACKS) {
 636                                 fprintf(stderr,"MThd too many (%u) tracks\n",tracks);
 637                                 goto err;
 638                         }
 639                         tdiv = tmp[5] | (tmp[4] << 8);
 640                         if (tdiv & 0x8000) {
 641                                 fprintf(stderr,"MThd SMPTE time division not supported\n");
 642                                 goto err; /* we do not support the SMPTE form */
 643                         }
 644                         if (tdiv == 0) {
 645                                 fprintf(stderr,"MThd time division == 0\n");
 646                                 goto err;
 647                         }
 648                         ticks_per_quarter_note = tdiv;
 649                 }
 650                 else if (!memcmp(tmp,"MTrk",4)) {
 651                         if (sz == 0UL) continue;
 652 #if TARGET_MSDOS == 16 && (defined(__LARGE__) || defined(__COMPACT__))
 653                         if (sz > (640UL << 10UL)) goto err; /* 640KB */
 654 #elif TARGET_MSDOS == 32
 655                         if (sz > (1UL << 20UL)) goto err; /* 1MB */
 656 #else
 657                         if (sz > (60UL << 10UL)) goto err; /* 60KB */
 658 #endif
 659                         if (tracki >= MIDI_MAX_TRACKS) goto err;
 660 #if TARGET_MSDOS == 16 && (defined(__LARGE__) || defined(__COMPACT__))
 661                         {
 662                                 unsigned segv;
 663
 664                                 /* NTS: _fmalloc() is still limited to 64KB sizes */
 665                                 if (_dos_allocmem((unsigned)((sz+15UL)>>4UL),&segv) != 0) goto err;
 666                                 midi_trk[tracki].raw = MK_FP(segv,0);
 667                         }
 668 #else
 669                         midi_trk[tracki].raw = malloc(sz);
 670 #endif
 671                         if (midi_trk[tracki].raw == NULL) goto err;
 672                         midi_trk[tracki].read = midi_trk[tracki].raw;
 673 #if TARGET_MSDOS == 16 && (defined(__LARGE__) || defined(__COMPACT__))
 674                         {
 675                                 unsigned char far *p = midi_trk[tracki].raw;
 676                                 unsigned long rem = (unsigned long)sz;
 677                                 unsigned long cando;
 678                                 unsigned read;
 679
 680                                 while (rem != 0UL) {
 681                                         read = 0;
 682
 683                                         cando = 0x10000UL - (unsigned long)FP_OFF(p);
 684                                         if (cando > rem) cando = rem;
 685                                         if (cando > 0xFFFFUL) cando = 0xFFFFUL; /* we're limited to 64KB-1 of reading */
 686
 687                                         if (_dos_read(fd,p,(unsigned)cando,&read) != 0) goto err;
 688                                         if (read != (unsigned)cando) goto err;
 689
 690                                         rem -= cando;
 691                                         if ((((unsigned long)FP_OFF(p))+cando) == 0x10000UL)
 692                                                 p = MK_FP(FP_SEG(p)+0x1000,0);
 693                                         else
 694                                                 p += (unsigned)cando;
 695                                 }
 696
 697                                 cando = farptr2phys(p);
 698                                 midi_trk[tracki].fence = MK_FP(cando>>4,cando&0xF);
 699                         }
 700 #else
 701                         midi_trk[tracki].fence = midi_trk[tracki].raw + (unsigned)sz;
 702                         if (read(fd,midi_trk[tracki].raw,(unsigned)sz) != (int)sz) goto err;
 703 #endif
 704                         tracki++;
 705                 }
 706                 else {
 707                         fprintf(stderr,"Unknown MIDI chunk %c%c%c%c\n",tmp[0],tmp[1],tmp[2],tmp[3]);
 708                         goto err;
 709                 }
 710         }
 711         if (tracki == 0 || ticks_per_quarter_note == 0) goto err;
 712         midi_trk_count = tracki;
 713
 714         fprintf(stderr,"Ticks per quarter note: %u\n",ticks_per_quarter_note);
 715
 716         close(fd);
 717         return 1;
 718 err:
 719         close(fd);
 720         return 0;
 721 }