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--2005 Han-Wen Nienhuys <hanwen@cs.uu.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
  21 #include <Python.h>
  22
  23 #if 0
  24 int x = 0;
  25 int *track = &x;
  26 #define debug_print(f, args...) fprintf (stderr, "%s:%d: track: %p :" f, __FUNCTION__, __LINE__, *track, ##args)
  27 #else
  28 #define debug_print(f, args...)
  29 #endif
  30
  31 static PyObject *Midi_error;
  32 static PyObject *Midi_warning;
  33
  34 static PyObject *
  35 midi_error (char const *func, char *s)
  36 {
  37   char*dest = (char*) malloc (sizeof (char) * (strlen (func) + strlen (s) + 1));
  38   strcpy (dest, func);
  39   strcat (dest, s);
  40   PyErr_SetString (Midi_error, dest);
  41   free (dest);
  42
  43   return 0;
  44 }
  45
  46 static PyObject *
  47 midi_warning (char const *s)
  48 {
  49   PyErr_SetString (Midi_warning, s);
  50   return 0;
  51 }
  52
  53
  54 typedef struct message {
  55   unsigned char msg;
  56   char * description;
  57 } message_t;
  58
  59 message_t channelVoiceMessages[] = {
  60   0x80, "NOTE_OFF",
  61   0x90, "NOTE_ON",
  62   0xA0, "POLYPHONIC_KEY_PRESSURE",
  63   0xB0, "CONTROLLER_CHANGE",
  64   0xC0, "PROGRAM_CHANGE",
  65   0xD0, "CHANNEL_KEY_PRESSURE",
  66   0xE0, "PITCH_BEND",
  67   0,0
  68 };
  69
  70 message_t channelModeMessages[] = {
  71   0x78, "ALL_SOUND_OFF",
  72   0x79, "RESET_ALL_CONTROLLERS",
  73   0x7A, "LOCAL_CONTROL",
  74   0x7B, "ALL_NOTES_OFF",
  75   0x7C, "OMNI_MODE_OFF",
  76   0x7D, "OMNI_MODE_ON",
  77   0x7E, "MONO_MODE_ON",
  78   0x7F, "POLY_MODE_ON",
  79   0,0
  80 };
  81
  82 message_t metaEvents[] = {
  83   0x00, "SEQUENCE_NUMBER",
  84   0x01, "TEXT_EVENT",
  85   0x02, "COPYRIGHT_NOTICE",
  86   0x03, "SEQUENCE_TRACK_NAME",
  87   0x04, "INSTRUMENT_NAME",
  88   0x05, "LYRIC",
  89   0x06, "MARKER",
  90   0x07, "CUE_POINT",
  91   0x20, "MIDI_CHANNEL_PREFIX",
  92   0x21, "MIDI_PORT",
  93   0x2F, "END_OF_TRACK",
  94   0x51, "SET_TEMPO",
  95   0x54, "SMTPE_OFFSET",
  96   0x58, "TIME_SIGNATURE",
  97   0x59, "KEY_SIGNATURE",
  98   0x7F, "SEQUENCER_SPECIFIC_META_EVENT",
  99   0xFF, "META_EVENT",
 100   0,0
 101 };
 102
 103 void
 104 add_constants (PyObject *dict)
 105 {
 106   message_t * p[] = {metaEvents, channelModeMessages, channelVoiceMessages ,0};
 107   int i,j;
 108   for ( j =0; p[j]; j++)
 109     for ( i = 0; p[j][i].description; i++)
 110       PyDict_SetItemString (dict, p[j][i].description, Py_BuildValue ("i", p[j][i].msg));
 111 }
 112
 113 unsigned long int
 114 get_number (unsigned char ** str, unsigned char * end_str, int length)
 115 {
 116   /* # MIDI uses big-endian for everything */
 117   long sum = 0;
 118   int i = 0;
 119
 120   for (; i < length; i++)
 121     sum = (sum << 8) + (unsigned char) (*str)[i];
 122
 123   *str += length;
 124   debug_print ("%d:\n", sum);
 125   return sum;
 126 }
 127
 128 unsigned long int
 129 get_variable_length_number (unsigned char **str, unsigned char * end_str)
 130 {
 131   long sum = 0;
 132   int i = 0;
 133   while (*str < end_str)
 134     {
 135       unsigned char x = **str;
 136       (*str) ++;
 137       sum = (sum << 7) + (x & 0x7F);
 138       if (!(x & 0x80))
 139         break;
 140     }
 141   debug_print ("%d:\n", sum);
 142   return sum;
 143 }
 144
 145 PyObject *
 146 read_one_byte (unsigned char **track, unsigned char *end,
 147                unsigned char x)
 148 {
 149   PyObject *pyev = Py_BuildValue ("(i)", x);
 150   debug_print ("%x:%s", x, "event\n");
 151
 152   return pyev;
 153 }
 154
 155 PyObject *
 156 read_two_bytes (unsigned char **track, unsigned char *end,
 157                 unsigned char x)
 158 {
 159   PyObject *pyev = Py_BuildValue ("(ii)", x, (*track)[0]);
 160   *track += 1;
 161   debug_print ("%x:%s", x, "event\n");
 162   return pyev;
 163 }
 164
 165 PyObject *
 166 read_three_bytes (unsigned char **track, unsigned char *end,
 167                   unsigned char x)
 168 {
 169   PyObject *pyev = Py_BuildValue ("(iii)", x, (*track)[0],
 170                                   (*track)[1]);
 171
 172   *track += 2;
 173   debug_print ("%x:%s", x, "event\n");
 174   return pyev;
 175 }
 176
 177 PyObject *
 178 read_string (unsigned char **track, unsigned char *end)
 179 {
 180   unsigned long length = get_variable_length_number (track, end);
 181   if (length > end - *track)
 182     length = end - *track;
 183
 184   *track += length;
 185   return Py_BuildValue ("s#", ((*track) -length), length);
 186 }
 187
 188 typedef PyObject* (*Read_midi_event)
 189      (unsigned char **track, unsigned char *end,
 190       unsigned char x);
 191
 192
 193 static PyObject *
 194 read_f0_byte (unsigned char **track, unsigned char *end,
 195               unsigned char x)
 196
 197 {
 198   debug_print ("%x:%s", x, "event\n");
 199   if (x == 0xff)
 200     {
 201       unsigned char z = (*track)[0 ];
 202       *track += 1;
 203       debug_print ("%x:%s", z, "f0-event\n");
 204
 205       return Py_BuildValue ("(iiO)", x, z, read_string (track, end));
 206     }
 207
 208   return Py_BuildValue ("(iO)", x, read_string (track, end));
 209 }
 210
 211 Read_midi_event read_midi_event [16] =
 212 {
 213   read_one_byte,  //  0
 214   read_one_byte,  // 10
 215   read_one_byte,  // 20
 216   read_one_byte,  // 30
 217   read_one_byte,  // 40
 218   read_one_byte,  // 50
 219   read_one_byte,  // 60 data entry.
 220   read_two_bytes, // 70 all notes off
 221   read_three_bytes, // 80 note off
 222   read_three_bytes, // 90 note on
 223   read_three_bytes, // a0 poly aftertouch
 224   read_three_bytes, // b0 control
 225   read_two_bytes,  // c0 prog change
 226   read_two_bytes, // d0 ch aftertouch
 227   read_three_bytes, // e0 pitchwheel range
 228   read_f0_byte,   // f0
 229 };
 230
 231
 232 static PyObject *
 233 read_event (unsigned char **track, unsigned char *end, PyObject *time,
 234             unsigned char *running_status)
 235 {
 236   int rsb_skip = ((**track & 0x80)) ? 1 :0;
 237
 238   unsigned char x = (rsb_skip) ? (*track)[0]: *running_status;
 239
 240   PyObject * bare_event = 0;
 241   debug_print ("%x:%s", x, "event\n");
 242   *running_status = x;
 243   *track += rsb_skip;
 244
 245   //  printf ("%x %x %d next %x\n", x, (*track)[0], rsb_skip, (*track)[1]);
 246   bare_event = (*read_midi_event[x >> 4]) (track, end, x);
 247   if (bare_event)
 248     return Py_BuildValue ("(OO)", time, bare_event);
 249   else
 250     return NULL;
 251 }
 252
 253 static PyObject *
 254 midi_parse_track (unsigned char **track, unsigned char *track_end)
 255 {
 256   unsigned int time = 0;
 257   unsigned char running_status;
 258   unsigned long track_len, track_size;
 259   PyObject *pytrack = 0;
 260
 261   debug_print ("%s", "\n");
 262
 263   track_size = track_end - *track;
 264
 265   debug_print ("%s", "\n");
 266   if (strcmp (*track, "MTrk"))
 267     return midi_error (__FUNCTION__,  ": MTrk expected");
 268
 269   *track += 4;
 270
 271   track_len = get_number (track, *track + 4, 4);
 272
 273
 274   debug_print ("track_len: %u\n", track_len);
 275   debug_print ("track_size: %u\n", track_size);
 276   debug_print ("track begin: %p\n", track);
 277   debug_print ("track end: %p\n", track + track_len);
 278
 279   if (track_len > track_size)
 280     return midi_error (__FUNCTION__,  ": track size corrupt");
 281
 282   pytrack = PyList_New (0);
 283
 284   track_end = *track + track_len;
 285
 286   {
 287     PyObject *pytime = PyInt_FromLong (0L);
 288     while (*track < track_end)
 289       {
 290         long dt = get_variable_length_number(track, track_end);
 291         PyObject *pyev = 0;
 292
 293         time += dt;
 294         if (dt)
 295           pytime = PyInt_FromLong (time);
 296
 297         pyev = read_event (track, track_end, pytime,
 298                            &running_status);
 299         if (pyev)
 300           PyList_Append (pytrack, pyev);
 301       }
 302   }
 303
 304   *track = track_end;
 305   return pytrack;
 306 }
 307
 308
 309 static PyObject *
 310 pymidi_parse_track (PyObject *self, PyObject *args)
 311 {
 312   unsigned char *track, *track_end;
 313   unsigned long track_size, track_len;
 314
 315   PyObject * sobj = PyTuple_GetItem (args, 0);
 316
 317   debug_print ("%s", "\n");
 318   if (!PyArg_ParseTuple (args, "s#", &track, &track_size))
 319     return 0;
 320
 321   if (track_size < 0)
 322     return midi_error (__FUNCTION__,   ": negative track size");
 323
 324   track_end = track + track_size;
 325
 326   return midi_parse_track (&track, track_end);
 327 }
 328
 329 static PyObject *
 330 midi_parse (unsigned char **midi,unsigned  char *midi_end)
 331 {
 332   PyObject *pymidi = 0;
 333   unsigned long header_len;
 334   unsigned format, tracks;
 335   int division;
 336   int i;
 337
 338   debug_print ("%s", "\n");
 339
 340   /* Header */
 341   header_len = get_number (midi, *midi + 4, 4);
 342
 343
 344   if (header_len < 6)
 345     return midi_error (__FUNCTION__,  ": header too short");
 346
 347   format = get_number (midi, *midi + 2, 2);
 348   tracks = get_number (midi, *midi + 2, 2);
 349
 350   if (tracks > 32)
 351     return midi_error (__FUNCTION__,  ": too many tracks");
 352
 353   division = get_number (midi, *midi + 2, 2) * 4;
 354
 355
 356   if (division < 0)
 357     /* return midi_error ("can't handle non-metrical time"); */
 358     ;
 359   *midi += header_len - 6;
 360
 361   pymidi = PyList_New (0);
 362
 363   /* Tracks */
 364   for (i = 0; i < tracks; i++)
 365     PyList_Append (pymidi, midi_parse_track (midi, midi_end));
 366
 367   pymidi = Py_BuildValue ("(OO)", Py_BuildValue ("(ii)", format, division),
 368                           pymidi);
 369   return pymidi;
 370 }
 371
 372 static PyObject *
 373 pymidi_parse (PyObject *self, PyObject *args)
 374 {
 375   unsigned char *midi, *midi_end;
 376   unsigned long midi_size, midi_len;
 377
 378   PyObject *sobj = PyTuple_GetItem (args, 0);
 379
 380   debug_print ("%s", "\n");
 381   if (!PyArg_ParseTuple (args, "s#", &midi, &midi_size))
 382     return 0;
 383
 384   if (strcmp (midi, "MThd"))
 385       return midi_error (__FUNCTION__,  ": MThd expected");
 386
 387   midi += 4;
 388
 389   midi_end = midi + midi_size;
 390
 391   return midi_parse (&midi, midi_end);
 392 }
 393
 394
 395 static PyMethodDef MidiMethods[] =
 396 {
 397   {"parse",  pymidi_parse, 1},
 398   {"parse_track",  pymidi_parse_track, 1},
 399   {0, 0}        /* Sentinel */
 400 };
 401
 402 void
 403 initmidi ()
 404 {
 405   PyObject *m, *d;
 406   m = Py_InitModule ("midi", MidiMethods);
 407   d = PyModule_GetDict (m);
 408
 409   Midi_error = PyString_FromString ("midi.error");
 410   PyDict_SetItemString (d, "error", Midi_error);
 411   add_constants (d);
 412   Midi_warning = PyString_FromString ("midi.warning");
 413   PyDict_SetItemString (d, "warning", Midi_warning);
 414 }