python/midi.c

   1 /*
   2   midi.c -- implement Python midi parser module
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2001--2008 Han-Wen Nienhuys <hanwen@xs4all.nl>
   7             Jan Nieuwenhuizen <janneke@gnu.org>
   8
   9 */
  10
  11 /*
  12
  13 python
  14 import midi
  15 s = open ("s.midi").read ()
  16 midi.parse_track (s)
  17 midi.parse (s)
  18
  19
  20 returns a MIDI file as the tuple
  21
  22  (format, division, TRACKLIST)
  23
  24 each track is an EVENTLIST, where EVENT is
  25
  26   (time, (type, ARG1, [ARG2]))
  27
  28 */
  29
  30 #include <Python.h>
  31
  32 /* PyMIDINIT_FUNC isn't defined in Python < 2.3 */
  33 #ifndef PyMODINIT_FUNC
  34 #       if defined(__cplusplus)
  35 #               define PyMODINIT_FUNC extern "C" void
  36 #       else /* __cplusplus */
  37 #               define PyMODINIT_FUNC void
  38 #       endif /* __cplusplus */
  39 #endif
  40
  41 #if 0
  42 int x = 0;
  43 int *track = &x;
  44 #define debug_print(f, args...) fprintf (stderr, "%s:%d: track: %p :" f, __FUNCTION__, __LINE__, *track, ##args)
  45 #else
  46 #define debug_print(f, args...)
  47 #endif
  48
  49 static PyObject *Midi_error;
  50 static PyObject *Midi_warning;
  51
  52 static PyObject *
  53 midi_error (char const *func, char *s)
  54 {
  55   char *dest = (char*) malloc (sizeof (char) * (strlen (func) + strlen (s) + 1));
  56   strcpy (dest, func);
  57   strcat (dest, s);
  58   PyErr_SetString (Midi_error, dest);
  59   free (dest);
  60
  61   return 0;
  62 }
  63
  64 static PyObject *
  65 midi_warning (char const *s)
  66 {
  67   PyErr_SetString (Midi_warning, s);
  68   return 0;
  69 }
  70
  71
  72 typedef struct message {
  73   unsigned char msg;
  74   char * description;
  75 } message_t;
  76
  77 message_t channelVoiceMessages[] = {
  78   {0x80, "NOTE_OFF"},
  79   {0x90, "NOTE_ON"},
  80   {0xA0, "POLYPHONIC_KEY_PRESSURE"},
  81   {0xB0, "CONTROLLER_CHANGE"},
  82   {0xC0, "PROGRAM_CHANGE"},
  83   {0xD0, "CHANNEL_KEY_PRESSURE"},
  84   {0xE0, "PITCH_BEND"},
  85   {0,0}
  86 };
  87
  88 message_t channelModeMessages[] = {
  89   {0x78, "ALL_SOUND_OFF"},
  90   {0x79, "RESET_ALL_CONTROLLERS"},
  91   {0x7A, "LOCAL_CONTROL"},
  92   {0x7B, "ALL_NOTES_OFF"},
  93   {0x7C, "OMNI_MODE_OFF"},
  94   {0x7D, "OMNI_MODE_ON"},
  95   {0x7E, "MONO_MODE_ON"},
  96   {0x7F, "POLY_MODE_ON"},
  97   {0,0}
  98 };
  99
 100 message_t metaEvents[] = {
 101   {0x00, "SEQUENCE_NUMBER"},
 102   {0x01, "TEXT_EVENT"},
 103   {0x02, "COPYRIGHT_NOTICE"},
 104   {0x03, "SEQUENCE_TRACK_NAME"},
 105   {0x04, "INSTRUMENT_NAME"},
 106   {0x05, "LYRIC"},
 107   {0x06, "MARKER"},
 108   {0x07, "CUE_POINT"},
 109   {0x20, "MIDI_CHANNEL_PREFIX"},
 110   {0x21, "MIDI_PORT"},
 111   {0x2F, "END_OF_TRACK"},
 112   {0x51, "SET_TEMPO"},
 113   {0x54, "SMTPE_OFFSET"},
 114   {0x58, "TIME_SIGNATURE"},
 115   {0x59, "KEY_SIGNATURE"},
 116   {0x7F, "SEQUENCER_SPECIFIC_META_EVENT"},
 117   {0xFF, "META_EVENT"},
 118   {0,0}
 119 };
 120
 121 void
 122 add_constants (PyObject *dict)
 123 {
 124   message_t * p[] = {metaEvents, channelModeMessages, channelVoiceMessages ,0};
 125   int i,j;
 126   for ( j =0; p[j]; j++)
 127     for ( i = 0; p[j][i].description; i++)
 128       PyDict_SetItemString (dict, p[j][i].description, Py_BuildValue ("i", p[j][i].msg));
 129 }
 130
 131 unsigned long int
 132 get_number (unsigned char ** str, unsigned char * end_str, int length)
 133 {
 134   /* # MIDI uses big-endian for everything */
 135   long sum = 0;
 136   int i = 0;
 137
 138   for (; i < length &&
 139          ((*str) + i < end_str); i++)
 140     sum = (sum << 8) + (unsigned char) (*str)[i];
 141
 142   *str += length;
 143   debug_print ("%d:\n", sum);
 144   return sum;
 145 }
 146
 147 unsigned long int
 148 get_variable_length_number (unsigned char **str, unsigned char * end_str)
 149 {
 150   long sum = 0;
 151
 152   while (*str < end_str)
 153     {
 154       unsigned char x = **str;
 155       (*str) ++;
 156       sum = (sum << 7) + (x & 0x7F);
 157       if (!(x & 0x80))
 158         break;
 159     }
 160   debug_print ("%d:\n", sum);
 161   return sum;
 162 }
 163
 164 PyObject *
 165 read_one_byte (unsigned char **track, unsigned char *end,
 166                unsigned char x)
 167 {
 168   PyObject *pyev = Py_BuildValue ("(i)", x);
 169   debug_print ("%x:%s", x, "event\n");
 170
 171   return pyev;
 172 }
 173
 174 PyObject *
 175 read_two_bytes (unsigned char **track, unsigned char *end,
 176                 unsigned char x)
 177 {
 178   PyObject *pyev = Py_BuildValue ("(ii)", x, (*track)[0]);
 179   *track += 1;
 180   debug_print ("%x:%s", x, "event\n");
 181   return pyev;
 182 }
 183
 184 PyObject *
 185 read_three_bytes (unsigned char **track, unsigned char *end,
 186                   unsigned char x)
 187 {
 188   PyObject *pyev = Py_BuildValue ("(iii)", x, (*track)[0],
 189                                   (*track)[1]);
 190
 191   *track += 2;
 192   debug_print ("%x:%s", x, "event\n");
 193   return pyev;
 194 }
 195
 196 PyObject *
 197 read_string (unsigned char **track, unsigned char *end)
 198 {
 199   unsigned long length = get_variable_length_number (track, end);
 200   if (length > end - *track)
 201     length = end - *track;
 202
 203   *track += length;
 204   return Py_BuildValue ("s#", ((*track) -length), length);
 205 }
 206
 207 typedef PyObject* (*Read_midi_event)
 208   (unsigned char **track, unsigned char *end,
 209    unsigned char x);
 210
 211
 212 static PyObject *
 213 read_f0_byte (unsigned char **track, unsigned char *end,
 214               unsigned char x)
 215
 216 {
 217   debug_print ("%x:%s", x, "event\n");
 218   if (x == 0xff)
 219     {
 220       unsigned char z = (*track)[0 ];
 221       *track += 1;
 222       debug_print ("%x:%s", z, "f0-event\n");
 223
 224       return Py_BuildValue ("(iiO)", x, z, read_string (track, end));
 225     }
 226
 227   return Py_BuildValue ("(iO)", x, read_string (track, end));
 228 }
 229
 230 Read_midi_event read_midi_event [16] =
 231 {
 232   read_one_byte,  //  0
 233   read_one_byte,  // 10
 234   read_one_byte,  // 20
 235   read_one_byte,  // 30
 236   read_one_byte,  // 40
 237   read_one_byte,  // 50
 238   read_one_byte,  // 60 data entry.
 239   read_two_bytes, // 70 all notes off
 240   read_three_bytes, // 80 note off
 241   read_three_bytes, // 90 note on
 242   read_three_bytes, // a0 poly aftertouch
 243   read_three_bytes, // b0 control
 244   read_two_bytes,  // c0 prog change
 245   read_two_bytes, // d0 ch aftertouch
 246   read_three_bytes, // e0 pitchwheel range
 247   read_f0_byte,   // f0
 248 };
 249
 250
 251 static PyObject *
 252 read_event (unsigned char **track, unsigned char *end, PyObject *time,
 253             unsigned char *running_status)
 254 {
 255   int rsb_skip = ((**track & 0x80)) ? 1 :0;
 256
 257   unsigned char x = (rsb_skip) ? (*track)[0]: *running_status;
 258
 259   PyObject * bare_event = 0;
 260   debug_print ("%x:%s", x, "event\n");
 261   *running_status = x;
 262   *track += rsb_skip;
 263
 264   //  printf ("%x %x %d next %x\n", x, (*track)[0], rsb_skip, (*track)[1]);
 265   bare_event = (*read_midi_event[x >> 4]) (track, end, x);
 266   if (bare_event)
 267     return Py_BuildValue ("(OO)", time, bare_event);
 268   else
 269     return NULL;
 270 }
 271
 272 static PyObject *
 273 midi_parse_track (unsigned char **track, unsigned char *track_end)
 274 {
 275   unsigned int time = 0;
 276   unsigned long track_len, track_size;
 277   PyObject *pytrack = 0;
 278
 279   debug_print ("%s", "\n");
 280
 281   track_size = track_end - *track;
 282
 283   debug_print ("%s", "\n");
 284   if (memcmp (*track, "MTrk", 4))
 285     return midi_error (__FUNCTION__,  ": MTrk expected");
 286
 287   *track += 4;
 288
 289   track_len = get_number (track, *track + 4, 4);
 290
 291
 292   debug_print ("track_len: %u\n", track_len);
 293   debug_print ("track_size: %u\n", track_size);
 294   debug_print ("track begin: %p\n", track);
 295   debug_print ("track end: %p\n", track + track_len);
 296
 297   if (track_len > track_size)
 298     return midi_error (__FUNCTION__,  ": track size corrupt");
 299
 300   pytrack = PyList_New (0);
 301
 302   if (*track + track_len < track_end)
 303     track_end = *track + track_len;
 304
 305   {
 306     PyObject *pytime = PyInt_FromLong (0L);
 307     unsigned char running_status = 0;
 308
 309     while (*track < track_end)
 310       {
 311         long dt = get_variable_length_number(track, track_end);
 312         PyObject *pyev = 0;
 313
 314         time += dt;
 315         if (dt)
 316           pytime = PyInt_FromLong (time);
 317
 318         pyev = read_event (track, track_end, pytime,
 319                            &running_status);
 320         if (pyev)
 321           PyList_Append (pytrack, pyev);
 322       }
 323   }
 324
 325   *track = track_end;
 326   return pytrack;
 327 }
 328
 329
 330 static PyObject *
 331 pymidi_parse_track (PyObject *self, PyObject *args)
 332 {
 333   unsigned char *track, *track_end;
 334   unsigned long track_size;
 335
 336   debug_print ("%s", "\n");
 337   if (!PyArg_ParseTuple (args, "s#", &track, &track_size))
 338     return 0;
 339
 340   if (track_size < 0)
 341     return midi_error (__FUNCTION__,   ": negative track size");
 342
 343   track_end = track + track_size;
 344
 345   return midi_parse_track (&track, track_end);
 346 }
 347
 348 static PyObject *
 349 midi_parse (unsigned char **midi,unsigned  char *midi_end)
 350 {
 351   PyObject *pymidi = 0;
 352   unsigned long header_len;
 353   unsigned format, tracks;
 354   int division;
 355   int i;
 356
 357   debug_print ("%s", "\n");
 358
 359   /* Header */
 360   header_len = get_number (midi, *midi + 4, 4);
 361
 362   if (header_len < 6)
 363     return midi_error (__FUNCTION__,  ": header too short");
 364
 365   format = get_number (midi, *midi + 2, 2);
 366   tracks = get_number (midi, *midi + 2, 2);
 367
 368   if (tracks > 32)
 369     return midi_error (__FUNCTION__,  ": too many tracks");
 370
 371   division = get_number (midi, *midi + 2, 2) * 4;
 372
 373
 374   if (division < 0)
 375     /* return midi_error (cannot handle non-metrical time"); */
 376     ;
 377   *midi += header_len - 6;
 378
 379   pymidi = PyList_New (0);
 380
 381   /* Tracks */
 382   for (i = 0; i < tracks; i++)
 383     PyList_Append (pymidi, midi_parse_track (midi, midi_end));
 384
 385   pymidi = Py_BuildValue ("(OO)", Py_BuildValue ("(ii)", format, division),
 386                           pymidi);
 387   return pymidi;
 388 }
 389
 390 static PyObject *
 391 pymidi_parse (PyObject *self, PyObject *args)
 392 {
 393   unsigned char *midi, *midi_end;
 394   unsigned long midi_size;
 395
 396   debug_print ("%s", "\n");
 397   if (!PyArg_ParseTuple (args, "s#", &midi, &midi_size))
 398     return 0;
 399
 400   if (memcmp (midi, "MThd", 4))
 401     return midi_error (__FUNCTION__,  ": MThd expected");
 402
 403   midi += 4;
 404
 405   midi_end = midi + midi_size;
 406
 407   return midi_parse (&midi, midi_end);
 408 }
 409
 410
 411 static PyMethodDef MidiMethods[] =
 412 {
 413   {"parse",  pymidi_parse, 1},
 414   {"parse_track",  pymidi_parse_track, 1},
 415   {0, 0}        /* Sentinel */
 416 };
 417
 418 PyMODINIT_FUNC
 419 initmidi (void)
 420 {
 421   PyObject *m, *d;
 422   m = Py_InitModule ("midi", MidiMethods);
 423   d = PyModule_GetDict (m);
 424
 425   Midi_error = PyString_FromString ("midi.error");
 426   PyDict_SetItemString (d, "error", Midi_error);
 427   add_constants (d);
 428   Midi_warning = PyString_FromString ("midi.warning");
 429   PyDict_SetItemString (d, "warning", Midi_warning);
 430
 431   /*
 432     FIXME.
 433    */
 434   (void) midi_warning;
 435 }
 436