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--2003 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 "config.h"
  22 #include <Python.h>
  23
  24 #if 0
  25 int x = 0;
  26 int *track = &x;
  27 #define debug_print(f, args...) fprintf (stderr, "%s:%d: track: %p :" f, __FUNCTION__, __LINE__, *track, ##args)
  28 #else
  29 #define debug_print(f, args...)
  30 #endif
  31
  32 static PyObject *Midi_error;
  33 static PyObject *Midi_warning;
  34
  35 static PyObject *
  36 midi_error (char const *func, char *s)
  37 {
  38   char*dest = (char*) malloc (sizeof (char) * (strlen (func) + strlen (s) + 1));
  39   strcpy (dest, func);
  40   strcat (dest, s);
  41   PyErr_SetString (Midi_error, dest);
  42   free (dest);
  43
  44   return 0;
  45 }
  46
  47 static PyObject *
  48 midi_warning (char const *s)
  49 {
  50   PyErr_SetString (Midi_warning, s);
  51   return 0;
  52 }
  53
  54
  55 typedef struct message {
  56   unsigned char msg;
  57   char * description;
  58 } message_t;
  59
  60 message_t channelVoiceMessages[] = {
  61   0x80, "NOTE_OFF",
  62   0x90, "NOTE_ON",
  63   0xA0, "POLYPHONIC_KEY_PRESSURE",
  64   0xB0, "CONTROLLER_CHANGE",
  65   0xC0, "PROGRAM_CHANGE",
  66   0xD0, "CHANNEL_KEY_PRESSURE",
  67   0xE0, "PITCH_BEND",
  68   0,0
  69 };
  70
  71 message_t channelModeMessages[] = {
  72   0x78, "ALL_SOUND_OFF",
  73   0x79, "RESET_ALL_CONTROLLERS",
  74   0x7A, "LOCAL_CONTROL",
  75   0x7B, "ALL_NOTES_OFF",
  76   0x7C, "OMNI_MODE_OFF",
  77   0x7D, "OMNI_MODE_ON",
  78   0x7E, "MONO_MODE_ON",
  79   0x7F, "POLY_MODE_ON",
  80   0,0
  81 };
  82
  83 message_t metaEvents[] = {
  84   0x00, "SEQUENCE_NUMBER",
  85   0x01, "TEXT_EVENT",
  86   0x02, "COPYRIGHT_NOTICE",
  87   0x03, "SEQUENCE_TRACK_NAME",
  88   0x04, "INSTRUMENT_NAME",
  89   0x05, "LYRIC",
  90   0x06, "MARKER",
  91   0x07, "CUE_POINT",
  92   0x20, "MIDI_CHANNEL_PREFIX",
  93   0x21, "MIDI_PORT",
  94   0x2F, "END_OF_TRACK",
  95   0x51, "SET_TEMPO",
  96   0x54, "SMTPE_OFFSET",
  97   0x58, "TIME_SIGNATURE",
  98   0x59, "KEY_SIGNATURE",
  99   0x7F, "SEQUENCER_SPECIFIC_META_EVENT",
 100   0xFF, "META_EVENT",
 101   0,0
 102 };
 103
 104 void
 105 add_constants (PyObject *dict)
 106 {
 107   message_t * p[] = {metaEvents, channelModeMessages, channelVoiceMessages ,0};
 108   int i,j;
 109   for ( j =0; p[j]; j++)
 110     for ( i = 0; p[j][i].description; i++)
 111       PyDict_SetItemString (dict, p[j][i].description, Py_BuildValue ("i", p[j][i].msg));
 112 }
 113
 114 unsigned long int
 115 get_number (unsigned char ** str, unsigned char * end_str, int length)
 116 {
 117   /* # MIDI uses big-endian for everything */
 118   long sum = 0;
 119   int i = 0;
 120
 121   for (; i < length; i++)
 122     sum = (sum << 8) + (unsigned char) (*str)[i];
 123
 124   *str += length;
 125   debug_print ("%d:\n", sum);
 126   return sum;
 127 }
 128
 129 unsigned long int
 130 get_variable_length_number (unsigned char **str, unsigned char * end_str)
 131 {
 132   long sum = 0;
 133   int i = 0;
 134   while (*str < end_str)
 135     {
 136       unsigned char x = **str;
 137       (*str) ++;
 138       sum = (sum << 7) + (x & 0x7F);
 139       if (!(x & 0x80))
 140         break;
 141     }
 142   debug_print ("%d:\n", sum);
 143   return sum;
 144 }
 145
 146 PyObject *
 147 read_one_byte (unsigned char **track, unsigned char *end,
 148                unsigned char x)
 149 {
 150   PyObject *pyev = Py_BuildValue ("(i)", x);
 151   debug_print ("%x:%s", x, "event\n");
 152
 153   return pyev;
 154 }
 155
 156 PyObject *
 157 read_two_bytes (unsigned char **track, unsigned char *end,
 158                 unsigned char x)
 159 {
 160   PyObject *pyev = Py_BuildValue ("(ii)", x, (*track)[0]);
 161   *track += 1;
 162   debug_print ("%x:%s", x, "event\n");
 163   return pyev;
 164 }
 165
 166 PyObject *
 167 read_three_bytes (unsigned char **track, unsigned char *end,
 168                   unsigned char x)
 169 {
 170   PyObject *pyev = Py_BuildValue ("(iii)", x, (*track)[0],
 171                                   (*track)[1]);
 172
 173   *track += 2;
 174   debug_print ("%x:%s", x, "event\n");
 175   return pyev;
 176 }
 177
 178 PyObject *
 179 read_string (unsigned char **track, unsigned char *end)
 180 {
 181   unsigned long length = get_variable_length_number (track, end);
 182   if (length > end - *track)
 183     length = end - *track;
 184
 185   *track += length;
 186   return Py_BuildValue ("s#", ((*track) -length), length);
 187 }
 188
 189 typedef PyObject* (*Read_midi_event)
 190      (unsigned char **track, unsigned char *end,
 191       unsigned char x);
 192
 193
 194 static PyObject *
 195 read_f0_byte (unsigned char **track, unsigned char *end,
 196               unsigned char x)
 197
 198 {
 199   debug_print ("%x:%s", x, "event\n");
 200   if (x == 0xff)
 201     {
 202       unsigned char z = (*track)[0 ];
 203       *track += 1;
 204       debug_print ("%x:%s", z, "f0-event\n");
 205
 206       return Py_BuildValue ("(iiO)", x, z, read_string (track, end));
 207     }
 208
 209   return Py_BuildValue ("(iO)", x, read_string (track, end));
 210 }
 211
 212 Read_midi_event read_midi_event [16] =
 213 {
 214   read_one_byte,  //  0
 215   read_one_byte,  // 10
 216   read_one_byte,  // 20
 217   read_one_byte,  // 30
 218   read_one_byte,  // 40
 219   read_one_byte,  // 50
 220   read_one_byte,  // 60 data entry.
 221   read_two_bytes, // 70 all notes off
 222   read_three_bytes, // 80 note off
 223   read_three_bytes, // 90 note on
 224   read_three_bytes, // a0 poly aftertouch
 225   read_three_bytes, // b0 control
 226   read_two_bytes,  // c0 prog change
 227   read_two_bytes, // d0 ch aftertouch
 228   read_three_bytes, // e0 pitchwheel range
 229   read_f0_byte,   // f0
 230 };
 231
 232
 233 static PyObject *
 234 read_event (unsigned char **track, unsigned char *end, PyObject *time,
 235             unsigned char *running_status)
 236 {
 237   int rsb_skip = ((**track & 0x80)) ? 1 :0;
 238
 239   unsigned char x = (rsb_skip) ? (*track)[0]: *running_status;
 240
 241   PyObject * bare_event = 0;
 242   debug_print ("%x:%s", x, "event\n");
 243   *running_status = x;
 244   *track += rsb_skip;
 245
 246   //  printf ("%x %x %d next %x\n", x, (*track)[0], rsb_skip, (*track)[1]);
 247   bare_event = (*read_midi_event[x >> 4]) (track, end, x);
 248   if (bare_event)
 249     return Py_BuildValue ("(OO)", time, bare_event);
 250   else
 251     return NULL;
 252 }
 253
 254 static PyObject *
 255 midi_parse_track (unsigned char **track, unsigned char *track_end)
 256 {
 257   unsigned int time = 0;
 258   unsigned char running_status;
 259   unsigned long track_len, track_size;
 260   PyObject *pytrack = 0;
 261
 262   debug_print ("%s", "\n");
 263
 264   track_size = track_end - *track;
 265
 266   debug_print ("%s", "\n");
 267   if (strcmp (*track, "MTrk"))
 268     return midi_error (__FUNCTION__,  ": MTrk expected");
 269
 270   *track += 4;
 271
 272   track_len = get_number (track, *track + 4, 4);
 273
 274
 275   debug_print ("track_len: %u\n", track_len);
 276   debug_print ("track_size: %u\n", track_size);
 277   debug_print ("track begin: %p\n", track);
 278   debug_print ("track end: %p\n", track + track_len);
 279
 280   if (track_len > track_size)
 281     return midi_error (__FUNCTION__,  ": track size corrupt");
 282
 283   pytrack = PyList_New (0);
 284
 285   track_end = *track + track_len;
 286
 287   {
 288     PyObject *pytime = PyInt_FromLong (0L);
 289     while (*track < track_end)
 290       {
 291         long dt = get_variable_length_number(track, track_end);
 292         PyObject *pyev = 0;
 293
 294         time += dt;
 295         if (dt)
 296           pytime = PyInt_FromLong (time);
 297
 298         pyev = read_event (track, track_end, pytime,
 299                            &running_status);
 300         if (pyev)
 301           PyList_Append (pytrack, pyev);
 302       }
 303   }
 304
 305   *track = track_end;
 306   return pytrack;
 307 }
 308
 309
 310 static PyObject *
 311 pymidi_parse_track (PyObject *self, PyObject *args)
 312 {
 313   unsigned char *track, *track_end;
 314   unsigned long track_size, track_len;
 315
 316   PyObject * sobj = PyTuple_GetItem (args, 0);
 317
 318   debug_print ("%s", "\n");
 319   if (!PyArg_ParseTuple (args, "s#", &track, &track_size))
 320     return 0;
 321
 322   if (track_size < 0)
 323     return midi_error (__FUNCTION__,   ": negative track size");
 324
 325   track_end = track + track_size;
 326
 327   return midi_parse_track (&track, track_end);
 328 }
 329
 330 static PyObject *
 331 midi_parse (unsigned char **midi,unsigned  char *midi_end)
 332 {
 333   PyObject *pymidi = 0;
 334   unsigned long header_len;
 335   unsigned format, tracks;
 336   int division;
 337   int i;
 338
 339   debug_print ("%s", "\n");
 340
 341   /* Header */
 342   header_len = get_number (midi, *midi + 4, 4);
 343
 344
 345   if (header_len < 6)
 346     return midi_error (__FUNCTION__,  ": header too short");
 347
 348   format = get_number (midi, *midi + 2, 2);
 349   tracks = get_number (midi, *midi + 2, 2);
 350
 351   if (tracks > 32)
 352     return midi_error (__FUNCTION__,  ": too many tracks");
 353
 354   division = get_number (midi, *midi + 2, 2) * 4;
 355
 356
 357   if (division < 0)
 358     /* return midi_error ("can't handle non-metrical time"); */
 359     ;
 360   *midi += header_len - 6;
 361
 362   pymidi = PyList_New (0);
 363
 364   /* Tracks */
 365   for (i = 0; i < tracks; i++)
 366     PyList_Append (pymidi, midi_parse_track (midi, midi_end));
 367
 368   pymidi = Py_BuildValue ("(OO)", Py_BuildValue ("(ii)", format, division),
 369                           pymidi);
 370   return pymidi;
 371 }
 372
 373 static PyObject *
 374 pymidi_parse (PyObject *self, PyObject *args)
 375 {
 376   unsigned char *midi, *midi_end;
 377   unsigned long midi_size, midi_len;
 378
 379   PyObject *sobj = PyTuple_GetItem (args, 0);
 380
 381   debug_print ("%s", "\n");
 382   if (!PyArg_ParseTuple (args, "s#", &midi, &midi_size))
 383     return 0;
 384
 385   if (strcmp (midi, "MThd"))
 386       return midi_error (__FUNCTION__,  ": MThd expected");
 387
 388   midi += 4;
 389
 390   midi_end = midi + midi_size;
 391
 392   return midi_parse (&midi, midi_end);
 393 }
 394
 395
 396 static PyMethodDef MidiMethods[] =
 397 {
 398   {"parse",  pymidi_parse, 1},
 399   {"parse_track",  pymidi_parse_track, 1},
 400   {0, 0}        /* Sentinel */
 401 };
 402
 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 }