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75 lines
1.6 KiB
75 lines
1.6 KiB
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#include <alsa/asoundlib.h>
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#include <alsa/seq.h>
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#include <sys/time.h>
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#include <sched.h>
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void
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callback(snd_seq_t *handle)
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{
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snd_seq_event_t *ev = 0;
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do {
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if (snd_seq_event_input(handle, &ev) > 0) {
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if (ev->type == SND_SEQ_EVENT_NOTEON) {
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struct timeval tv;
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static long last_usec = 0;
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int pitch = ev->data.note.note;
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snd_seq_timestamp_t evt = ev->time;
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gettimeofday(&tv, 0);
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printf("pitch %d at %ld sec %ld usec, off by %ld usec\n",
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pitch, tv.tv_sec, tv.tv_usec, tv.tv_usec - ((last_usec + 500000) % 1000000));
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last_usec = tv.tv_usec;
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}
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}
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} while (snd_seq_event_input_pending(handle, 0) > 0);
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}
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int
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main(int argc, char **argv)
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{
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snd_seq_t *handle;
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int portid;
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int npfd;
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struct pollfd *pfd;
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struct sched_param param;
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if (snd_seq_open(&handle, "hw", SND_SEQ_OPEN_DUPLEX, 0) < 0) {
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fprintf(stderr, "failed to open ALSA sequencer interface\n");
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return 1;
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}
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snd_seq_set_client_name(handle, "complainer");
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if ((portid = snd_seq_create_simple_port
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(handle, "complainer",
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SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE, 0)) < 0) {
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fprintf(stderr, "failed to create ALSA sequencer port\n");
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return 1;
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}
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npfd = snd_seq_poll_descriptors_count(handle, POLLIN);
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pfd = (struct pollfd *)alloca(npfd * sizeof(struct pollfd));
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snd_seq_poll_descriptors(handle, pfd, npfd, POLLIN);
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param.sched_priority = 99;
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if (sched_setscheduler(0, SCHED_FIFO, ¶m)) {
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perror("failed to set high-priority scheduler");
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}
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printf("ready\n", npfd);
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while (1) {
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if (poll(pfd, npfd, 100000) > 0) {
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callback(handle);
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}
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}
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}
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