housic/main.c

/*
 * Programmer: Dominik Schmidt-Philipp <schmidt-philipp@kulturteknologi.no>
 * Filename:   main.c
 *
 * Dedicated to seleomlivet
 *
 */
#include <alsa/asoundlib.h>
#include <pthread.h>             /* for threading        */


// function declarations:
void     alsa_error           (const char *format, ...);
void*    midiinfunction       (void * arg);
void     midi_in_dispatch     (void * arg, unsigned char * m);


typedef struct {
  snd_rawmidi_t* midiin;
  snd_rawmidi_t* midiout;
  unsigned char hui_in_zone;
} housicIO;

int main(int argc, char *argv[]) {
  int status;
  int mode = SND_RAWMIDI_SYNC;
  pthread_t midiinthread;

  housicIO IOs = {NULL,NULL,0};
  
  //  snd_rawmidi_t* midiin = NULL;
  const char* portname = "virtual";

  
  if ((status = snd_rawmidi_open(&IOs.midiin, NULL, portname, mode)) < 0) {
    alsa_error("Problem opening MIDI input: %s", snd_strerror(status));
    exit(1);
  }

  status = pthread_create(&midiinthread, NULL, midiinfunction, &IOs);
  
  pthread_join(midiinthread, NULL);

  //snd_rawmidi_close(midiin);
  //midiin=NULL;
  
  return 0;
}


//////////////////////////////
//
// midiinfunction -- Thread function which waits around until a MIDI 
//      input byte arrives and then react correspondingly
//

void *midiinfunction(void *arg) {
  housicIO* IOs = (housicIO*)arg;
  snd_rawmidi_t* midiin = IOs->midiin;
  int status;
  int i = 0;
  char buffer[3];
  unsigned char message[3];

  while (1) {
    if ((status = snd_rawmidi_read(midiin, buffer, 3)) < 0) {
      alsa_error("Problem reading MIDI input: %s", snd_strerror(status));
    }

    // in case of MIDI running status, value bytes need to not override status byte
    for (i=1; i<=status;i++) {
      message[3-i] = (unsigned char) buffer[status-i];
    }

    midi_in_dispatch(IOs,message);

    fflush(stdout);
  }
}



//////////////////////////////
//
// midi_in_dispatch -- Thread function which waits around until a MIDI 
//      input byte arrives and then react correspondingly
//

void midi_in_dispatch(void *arg, unsigned char *m) {
  housicIO* IOs = (housicIO*)arg;

  if (m[0] == 0xb0) {
    // received a CC message on MIDIchannel 1
    if (m[1] == 0x0f) {
      // received a zone select
      IOs->hui_in_zone = m[2];
    }

  }
}


//////////////////////////////
//
// error -- print error message
//

void alsa_error(const char *format, ...) {
   va_list ap;
   va_start(ap, format);
   vfprintf(stderr, format, ap);
   va_end(ap);
   putc('\n', stderr);
}