Initial commit

src/lsi/midi.c

@@ -0,0 +1,101 @@
+/* midi.c */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <err.h>
+#include <sys/midiio.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+#include "vm.h"
+
+#define PORT "/dev/music"
+
+int midi_fd;
+int midi_bytes;
+seq_event_rec midi_buf;
+int midi_initialised = 0;
+
+void midi_init(void)
+{
+	midi_fd = open(PORT, O_NONBLOCK | O_RDONLY, 0);
+	if (midi_fd == -1) {
+		err(1, "failed to open MIDI port");
+	}
+	midi_bytes = 0;
+	midi_initialised = 1;
+	vm_register_signal_fd(midi_fd, VM_MIDIQ);
+}
+
+void midi_close(void)
+{
+	printf("Closing MIDI\n");
+	ioctl(midi_fd, SEQUENCER_SYNC, NULL);
+	ioctl(midi_fd, SEQUENCER_RESET, NULL);
+	printf("...\n");
+	close(midi_fd);
+	printf("X.\n");
+	midi_fd = 0;
+	midi_initialised = 0;
+}
+
+/*
+ * Returns non-zero if we're interested in the packet
+ * received. Zero otherwise. 
+ */
+int midi_filter(void)
+{
+	switch (midi_buf.arr[0]) {
+	case SEQ_CHN_COMMON:
+		/* We don't care about the unit number - yet */
+		/* We don't care about the channel - yet */
+		if (midi_buf.arr[2] == 0xb0) /* cmd */
+			return 1;
+		return 0;
+	case SEQ_TIMING:
+		return 0;
+	default:
+		printf("Unknown MIDI message received\n");
+		return 0;
+	}
+}
+
+int midi_read(void)
+{
+	if (!midi_initialised)
+		return 0;
+
+	while (1) {
+		int rv;
+		int left = sizeof(midi_buf) - midi_bytes;
+		rv = read(midi_fd, midi_buf.arr + midi_bytes, left);
+		if (rv == -1) {
+			if (errno == EAGAIN)
+				return 0;
+			printf("Error reading from MIDI\n");
+			close(midi_fd);
+			midi_initialised = 0;
+		}
+		if (rv == 0)
+			return 0;
+		midi_bytes += rv;
+		if (midi_bytes == sizeof(midi_buf)) {
+			midi_bytes = 0;
+			if (midi_filter())
+				return 1;
+		}
+	}
+}
+
+
+/*
+ * Return the interesting bits of the MIDI command.
+ * The contents of this function is likely to change
+ * as we become interested in more types of MIDI device.
+ * Pre-condition: midi_filter() has returned 1
+ */
+void midi_getcmd(int *button, int *value)
+{
+	*button = midi_buf.arr[4];
+	*value = midi_buf.arr[6];
+}