linux/alsa/midi_unpack.h

   1 /*
   2  * Copyright (c) 2006,2007 Dmitry S. Baikov
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 2 of the License, or
   7  *  (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; if not, write to the Free Software
  16  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  17  */
  18
  19 #ifndef __jack_midi_unpack_h__
  20 #define __jack_midi_unpack_h__
  21
  22 enum {
  23     MIDI_UNPACK_MAX_MSG = 1024
  24 };
  25
  26 typedef struct
  27 {
  28     int pos, need, size;
  29     unsigned char data[MIDI_UNPACK_MAX_MSG];
  30 }
  31 midi_unpack_t;
  32
  33 static inline
  34 void midi_unpack_init(midi_unpack_t *u)
  35 {
  36     u->pos = 0;
  37     u->size = sizeof(u->data);
  38     u->need = u->size;
  39 }
  40
  41 static inline
  42 void midi_unpack_reset(midi_unpack_t *u)
  43 {
  44     u->pos = 0;
  45     u->need = u->size;
  46 }
  47
  48 static const unsigned char midi_voice_len[] =
  49     {
  50         3, /*0x80 Note Off*/
  51         3, /*0x90 Note On*/
  52         3, /*0xA0 Aftertouch*/
  53         3, /*0xB0 Control Change*/
  54         2, /*0xC0 Program Change*/
  55         2, /*0xD0 Channel Pressure*/
  56         3, /*0xE0 Pitch Wheel*/
  57         1  /*0xF0 System*/
  58     };
  59
  60 static const unsigned char midi_system_len[] =
  61     {
  62         0, /*0xF0 System Exclusive Start*/
  63         2, /*0xF1 MTC Quarter Frame*/
  64         3, /*0xF2 Song Position*/
  65         2, /*0xF3 Song Select*/
  66         0, /*0xF4 undefined*/
  67         0, /*0xF5 undefined*/
  68         1, /*0xF6 Tune Request*/
  69         1  /*0xF7 System Exclusive End*/
  70     };
  71
  72 static
  73 int midi_unpack_buf(midi_unpack_t *buf, const unsigned char *data, int len, void *jack_port_buf, jack_nframes_t time)
  74 {
  75     int i;
  76     for (i = 0; i < len; ++i) {
  77         const unsigned char byte = data[i];
  78         if (byte >= 0xF8) // system realtime
  79         {
  80             jack_midi_event_write(jack_port_buf, time, &data[i], 1);
  81             //printf("midi_unpack: written system relatime event\n");
  82             //midi_input_write(in, &data[i], 1);
  83         } else if (byte < 0x80) // data
  84         {
  85             assert (buf->pos < buf->size);
  86             buf->data[buf->pos++] = byte;
  87         } else if (byte < 0xF0) // voice
  88         {
  89             assert (byte >= 0x80 && byte < 0xF0);
  90             //buf->need = ((byte|0x0F) == 0xCF || (byte|0x0F)==0xDF) ? 2 : 3;
  91             buf->need = midi_voice_len[(byte-0x80)>>4];
  92             buf->data[0] = byte;
  93             buf->pos = 1;
  94         } else if (byte == 0xF7) // sysex end
  95         {
  96             assert (buf->pos < buf->size);
  97             buf->data[buf->pos++] = byte;
  98             buf->need = buf->pos;
  99         } else {
 100             assert (byte >= 0xF0 && byte < 0xF8);
 101             buf->pos = 1;
 102             buf->data[0] = byte;
 103             buf->need = midi_system_len[byte - 0xF0];
 104             if (!buf->need)
 105                 buf->need = buf->size;
 106         }
 107         if (buf->pos == buf->need) {
 108             // TODO: deal with big sysex'es (they are silently dropped for now)
 109             if (buf->data[0] >= 0x80 || (buf->data[0] == 0xF0 && buf->data[buf->pos-1] == 0xF7)) {
 110                 /* convert Note On with velocity 0 to Note Off */
 111                 if ((buf->data[0] & 0xF0) == 0x90 && buf->data[2] == 0) {
 112                     // we use temp array here to keep running status sync
 113                     jack_midi_data_t temp[3] = { 0x80, 0, 0x40 };
 114                     temp[0] |= buf->data[0] & 0x0F;
 115                     temp[1] = buf->data[1];
 116                     jack_midi_event_write(jack_port_buf, time, temp, 3);
 117                 } else
 118                     jack_midi_event_write(jack_port_buf, time, &buf->data[0], buf->pos);
 119                 //printf("midi_unpack: written %d-byte event\n", buf->pos);
 120                 //midi_input_write(in, &buf->data[0], buf->pos);
 121             }
 122             /* keep running status */
 123             if (buf->data[0] >= 0x80 && buf->data[0] < 0xF0)
 124                 buf->pos = 1;
 125             else {
 126                 buf->pos = 0;
 127                 buf->need = buf->size;
 128             }
 129         }
 130     }
 131     assert (i == len);
 132     return i;
 133 }
 134
 135 #endif /* __jack_midi_unpack_h__ */