hdjd/alsa.c

175 lines
3.4 KiB
C

#include <stdio.h>
#include <poll.h>
#include <sys/select.h>
#include <alsa/asoundlib.h>
#include "alsa.h"
#include "usb.h"
#include "log.h"
#include "dump.h"
static snd_seq_t *snd_handle;
static int seq_port;
static snd_midi_event_t *midi_event_parser;
#define ALSA_BUFSIZE 4096
int
alsa_setup(const char *name)
{
if (snd_seq_open(&snd_handle, "default", SND_SEQ_OPEN_DUPLEX, 0) < 0) {
perror("snd_seq_open");
return -1;
}
snd_seq_nonblock(snd_handle, 1);
snd_seq_set_client_name(snd_handle, name);
seq_port =
snd_seq_create_simple_port(snd_handle, name,
SND_SEQ_PORT_CAP_READ | SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_READ |
SND_SEQ_PORT_CAP_SUBS_WRITE, SND_SEQ_PORT_TYPE_MIDI_GENERIC);
// Allocate parser object for converting to and from MIDI
if (snd_midi_event_new(ALSA_BUFSIZE, &midi_event_parser) < 0) {
fatal("ALSA cannot allocate MIDI event parser");
}
return 0;
}
void
alsa_close()
{
snd_midi_event_free(midi_event_parser);
}
#define MAX_PFDS 20
int npfd;
struct pollfd pfd[MAX_PFDS];
void
alsa_fd_setup(int *nfds, fd_set *rfds, fd_set *wfds)
{
npfd = snd_seq_poll_descriptors_count(snd_handle, POLLIN);
int i;
if (npfd > MAX_PFDS) {
fatal("ALSA wants too many file descriptors");
}
snd_seq_poll_descriptors(snd_handle, pfd, npfd, POLLIN);
for (i = 0; i < npfd; i += 1) {
if (pfd[i].fd > *nfds) {
*nfds = pfd[i].fd;
}
if (pfd[i].events & POLLIN) {
FD_SET(pfd[i].fd, rfds);
}
}
}
void
alsa_read_ready()
{
snd_midi_event_init(midi_event_parser);
for (;;) {
snd_seq_event_t *ev;
unsigned char buf[ALSA_BUFSIZE];
long converted;
int r;
r = snd_seq_event_input(snd_handle, &ev);
if (r == -EAGAIN) {
// input queue empty
break;
} else if (r == -ENOSPC) {
warn("Input queue overflow");
continue;
} else if (r < 0) {
warn("snd_seq_event_input() = %d", r);
continue;
}
converted = snd_midi_event_decode(midi_event_parser, buf, ALSA_BUFSIZE, ev);
if (converted < 0) {
warn("Can't decode MIDI event type %x", ev->type);
continue;
}
if (converted < 3) {
int i;
warn("Uh oh, weird MIDI packet with length %ld (does this make sense if prefixed with 90?)", converted);
for (i = 0; i < converted; i += 1) {
fprintf(stderr, " %02x", buf[i]);
}
fprintf(stderr, "\n");
}
usb_write(buf, converted);
}
}
void
alsa_check_fds(fd_set *rfds, fd_set *wfds)
{
int i;
for (i = 0; i < npfd; i += 1) {
int fd = pfd[i].fd;
if (FD_ISSET(fd, rfds) || FD_ISSET(fd, wfds)) {
alsa_read_ready();
return;
}
}
}
void
alsa_write(uint8_t *data, size_t datalen)
{
size_t offset = 0;
snd_midi_event_init(midi_event_parser);
for (; datalen > offset;) {
snd_seq_event_t ev;
long encoded;
int r;
encoded = snd_midi_event_encode(midi_event_parser, data + offset, datalen - offset, &ev);
if (encoded <= 1) {
int i;
warn("Unable to encode MIDI message (%ld < %ld)", encoded, datalen);
fprintf(stderr, " ");
for (i = offset; i < datalen; i += 1) {
fprintf(stderr, "%02x ", data[i]);
}
fprintf(stderr, "\n");
return;
}
snd_seq_ev_set_direct(&ev);
snd_seq_ev_set_source(&ev, seq_port);
snd_seq_ev_set_subs(&ev);
r = snd_seq_event_output(snd_handle, &ev);
if (r < 0) {
warn("Couldn't write an output event");
}
if (r > 200) {
warn("Output buffer size %d", r);
}
offset += encoded;
}
snd_seq_drain_output(snd_handle);
}