/* seqdemo.c by Matthias Nagorni */#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <alsa/asoundlib.h>snd_seq_t *open_seq();void midi_action(snd_seq_t *seq_handle);snd_seq_t *open_seq() {  snd_seq_t *seq_handle;  int portid;  if (snd_seq_open(&seq_handle, "default", SND_SEQ_OPEN_INPUT, 0) < 0) {    fprintf(stderr, "Error opening ALSA sequencer.\n");    exit(1);  }  snd_seq_set_client_name(seq_handle, "ALSA Sequencer Demo");  if ((portid = snd_seq_create_simple_port(seq_handle, "ALSA Sequencer Demo",            SND_SEQ_PORT_CAP_WRITE|SND_SEQ_PORT_CAP_SUBS_WRITE,            SND_SEQ_PORT_TYPE_APPLICATION)) < 0) {    fprintf(stderr, "Error creating sequencer port.\n");    exit(1);  }  return(seq_handle);}void midi_action(snd_seq_t *seq_handle) {  snd_seq_event_t *ev;  do {    snd_seq_event_input(seq_handle, &ev);    switch (ev->type) {      case SND_SEQ_EVENT_CONTROLLER:         fprintf(stderr, "Control event on Channel %2d: %5d       \r",                ev->data.control.channel, ev->data.control.value);        break;      case SND_SEQ_EVENT_PITCHBEND:        fprintf(stderr, "Pitchbender event on Channel %2d: %5d   \r",                 ev->data.control.channel, ev->data.control.value);        break;      case SND_SEQ_EVENT_NOTEON:        fprintf(stderr, "Note On event on Channel %2d: %5d       \r",                ev->data.control.channel, ev->data.note.note);        break;              case SND_SEQ_EVENT_NOTEOFF:         fprintf(stderr, "Note Off event on Channel %2d: %5d      \r",                         ev->data.control.channel, ev->data.note.note);                   break;            }    snd_seq_free_event(ev);  } while (snd_seq_event_input_pending(seq_handle, 0) > 0);}int main(int argc, char *argv[]) {  snd_seq_t *seq_handle;  int npfd;  struct pollfd *pfd;      seq_handle = open_seq();  npfd = snd_seq_poll_descriptors_count(seq_handle, POLLIN);  pfd = (struct pollfd *)alloca(npfd * sizeof(struct pollfd));  snd_seq_poll_descriptors(seq_handle, pfd, npfd, POLLIN);  while (1) {    if (poll(pfd, npfd, 100000) > 0) {      midi_action(seq_handle);    }    }}