/* miniArp.c by Matthias Nagorni */#include <stdio.h>#include <stdlib.h>#include <signal.h>#include <alsa/asoundlib.h>#define TICKS_PER_QUARTER 128#define MAX_SEQ_LEN        64int queue_id, port_in_id, port_out_id, transpose, bpm0, bpm, tempo, swing, sequence[3][MAX_SEQ_LEN], seq_len;snd_seq_t *seq_handle;char seq_filename[1024];snd_seq_tick_time_t tick;snd_seq_t *open_seq() {  snd_seq_t *seq_handle;  if (snd_seq_open(&seq_handle, "default", SND_SEQ_OPEN_DUPLEX, 0) < 0) {    fprintf(stderr, "Error opening ALSA sequencer.\n");    exit(1);  }  snd_seq_set_client_name(seq_handle, "miniArp");  if ((port_out_id = snd_seq_create_simple_port(seq_handle, "miniArp",            SND_SEQ_PORT_CAP_READ|SND_SEQ_PORT_CAP_SUBS_READ,            SND_SEQ_PORT_TYPE_APPLICATION)) < 0) {    fprintf(stderr, "Error creating sequencer port.\n");  }  if ((port_in_id = snd_seq_create_simple_port(seq_handle, "miniArp",            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 set_tempo() {  snd_seq_queue_tempo_t *queue_tempo;  snd_seq_queue_tempo_malloc(&queue_tempo);  tempo = (int)(6e7 / ((double)bpm * (double)TICKS_PER_QUARTER) * (double)TICKS_PER_QUARTER);  snd_seq_queue_tempo_set_tempo(queue_tempo, tempo);  snd_seq_queue_tempo_set_ppq(queue_tempo, TICKS_PER_QUARTER);  snd_seq_set_queue_tempo(seq_handle, queue_id, queue_tempo);  snd_seq_queue_tempo_free(queue_tempo);}snd_seq_tick_time_t get_tick() {  snd_seq_queue_status_t *status;  snd_seq_tick_time_t current_tick;    snd_seq_queue_status_malloc(&status);  snd_seq_get_queue_status(seq_handle, queue_id, status);  current_tick = snd_seq_queue_status_get_tick_time(status);  snd_seq_queue_status_free(status);  return(current_tick);}void init_queue() {  queue_id = snd_seq_alloc_queue(seq_handle);  snd_seq_set_client_pool_output(seq_handle, (seq_len<<1) + 4);}void clear_queue() {  snd_seq_remove_events_t *remove_ev;  snd_seq_remove_events_malloc(&remove_ev);  snd_seq_remove_events_set_queue(remove_ev, queue_id);  snd_seq_remove_events_set_condition(remove_ev, SND_SEQ_REMOVE_OUTPUT | SND_SEQ_REMOVE_IGNORE_OFF);  snd_seq_remove_events(seq_handle, remove_ev);  snd_seq_remove_events_free(remove_ev);}void arpeggio() {  snd_seq_event_t ev;  int l1;  double dt;   for (l1 = 0; l1 < seq_len; l1++) {    dt = (l1 % 2 == 0) ? (double)swing / 16384.0 : -(double)swing / 16384.0;    snd_seq_ev_clear(&ev);    snd_seq_ev_set_note(&ev, 0, sequence[2][l1] + transpose, 127, sequence[1][l1]);    snd_seq_ev_schedule_tick(&ev, queue_id,  0, tick);    snd_seq_ev_set_source(&ev, port_out_id);    snd_seq_ev_set_subs(&ev);    snd_seq_event_output_direct(seq_handle, &ev);    tick += (int)((double)sequence[0][l1] * (1.0 + dt));  }  snd_seq_ev_clear(&ev);  ev.type = SND_SEQ_EVENT_ECHO;   snd_seq_ev_schedule_tick(&ev, queue_id,  0, tick);  snd_seq_ev_set_dest(&ev, snd_seq_client_id(seq_handle), port_in_id);  snd_seq_event_output_direct(seq_handle, &ev);}void midi_action() {  snd_seq_event_t *ev;  do {    snd_seq_event_input(seq_handle, &ev);    switch (ev->type) {      case SND_SEQ_EVENT_ECHO:        arpeggio();         break;      case SND_SEQ_EVENT_NOTEON:        clear_queue();        transpose = ev->data.note.note - 60;        tick = get_tick();        arpeggio();        break;              case SND_SEQ_EVENT_CONTROLLER:        if (ev->data.control.param == 1) {                     bpm = (int)((double)bpm0 * (1.0 + (double)ev->data.control.value / 127.0));          set_tempo();        }         break;      case SND_SEQ_EVENT_PITCHBEND:        swing = (double)ev->data.control.value;                break;    }    snd_seq_free_event(ev);  } while (snd_seq_event_input_pending(seq_handle, 0) > 0);}void parse_sequence() {  FILE *f;  char c;    if (!(f = fopen(seq_filename, "r"))) {    fprintf(stderr, "Couldn't open sequence file %s\n", seq_filename);    exit(1);  }  seq_len = 0;  while((c = fgetc(f))!=EOF) {    switch (c) {      case 'c':         sequence[2][seq_len] = 0; break;       case 'd':         sequence[2][seq_len] = 2; break;      case 'e':         sequence[2][seq_len] = 4; break;      case 'f':         sequence[2][seq_len] = 5; break;      case 'g':         sequence[2][seq_len] = 7; break;      case 'a':         sequence[2][seq_len] = 9; break;      case 'h':         sequence[2][seq_len] = 11; break;    }                        c =  fgetc(f);    if (c == '#') {      sequence[2][seq_len]++;      c =  fgetc(f);    }    sequence[2][seq_len] += 12 * atoi(&c);    c =  fgetc(f);    sequence[1][seq_len] = TICKS_PER_QUARTER / atoi(&c);    c =  fgetc(f);    sequence[0][seq_len] = TICKS_PER_QUARTER / atoi(&c);        seq_len++;  }  fclose(f);}void sigterm_exit(int sig) {  clear_queue();  sleep(2);  snd_seq_stop_queue(seq_handle, queue_id, NULL);  snd_seq_free_queue(seq_handle, queue_id);  exit(0);}int main(int argc, char *argv[]) {  int npfd, l1;  struct pollfd *pfd;      if (argc < 3) {     fprintf(stderr, "\n\nminiArp <beats per minute> <sequence file>\n");    exit(1);  }  bpm0 = atoi(argv[1]);  bpm = bpm0;  strcpy(seq_filename, argv[2]);   parse_sequence();  seq_handle = open_seq();  init_queue();  set_tempo();  arpeggio();  snd_seq_start_queue(seq_handle, queue_id, NULL);  snd_seq_drain_output(seq_handle);  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);  transpose = 0;  swing = 0;  tick = 0;  signal(SIGINT, sigterm_exit);            signal(SIGTERM, sigterm_exit);    arpeggio();  while (1) {    if (poll(pfd, npfd, 100000) > 0) {      for (l1 = 0; l1 < npfd; l1++) {        if (pfd[l1].revents > 0) midi_action();       }    }    }}