Initial import

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diff --git a/README.md b/README.md
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+Open Sound Control interface for Allen & Heath Xone:K2
+======================================================
+
+This small program implements OSC methods for an [A&H
+Xone:K2](https://www.allen-heath.com/ahproducts/xonek2/) MIDI control surface.
+
+The program is not intended to be a general solution for MIDI<-->OSC
+communication. This implements things the way I use them.  If you want
+something else, I gleefully encourage you to fork and modify the code.
+
+
+Installation
+------------
+
+You will need the development files for Guile and liblo installed, as well as
+[Meson](https://mesonbuild.com/).  Then:
+
+```
+meson setup build
+ninja -C build
+```
+
+Run with `build/x1k2-midi-osc` (no arguments) or install with `meson install build`.
+
+
+OSC methods - receive
+---------------------
+
+* `/x1k2/leds/<n> <colour>`
+  `<n>` = 1..32,101,102 (int)
+  `<colour>` = red,orange,green,off (string)
+  Turn LEDs on/off.  Numbering is from top left (1) to bottom right (32).  Top
+  right is number 4.  The two large buttons at the bottom are 101 (left) and
+  102 (right).
+
+
+License
+-------
+
+GPL3+
+
+
+Note
+----
+
+This project is not supported by, or in any way affiliated with, Allen&Heath (duh).
diff --git a/meson.build b/meson.build
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+project('x1k2-midi-osc', ['c'],
+        version: '0.1.0',
+        license: 'GPL3+',
+        default_options: ['buildtype=debugoptimized'])
+
+# Dependencies
+lo_dep = dependency('liblo', required: true)
+alsa_dep = dependency('alsa', required: true)
+
+executable('x1k2-midi-osc',
+           ['x1k2-midi-osc.c'],
+           dependencies: [lo_dep, alsa_dep],
+           install: true)
diff --git a/x1k2-midi-osc.c b/x1k2-midi-osc.c
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+++ b/x1k2-midi-osc.c
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+/*
+ * x1k2-midi-osc.c
+ *
+ * (c) 2023 Thomas White <taw@bitwiz.me.uk>
+ *
+ * X1K2-midi-osc is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * X1K2-midi-osc is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with X1K2-midi-osc.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+
+#include <alsa/asoundlib.h>
+#include <lo/lo.h>
+
+
+static void show_help(const char *s)
+{
+	printf("Syntax: %s [-h] [-d /dev/snd/midiXXXX]\n\n", s);
+	printf("MIDI to OSC interface for A&H Xone:K2\n"
+	       "\n"
+	       " -h, --help              Display this help message.\n"
+	       " -d, --device <dev>      MIDI device name.\n");
+}
+
+
+static void error_callback(int num, const char *msg, const char *path)
+{
+	fprintf(stderr, "liblo error %i (%s) for path %s\n", num, msg, path);
+}
+
+
+static void send_note_on(snd_rawmidi_t *midi_out, int note)
+{
+	unsigned char sbuf[3];
+	ssize_t r;
+	sbuf[0] = 0x9e;
+	sbuf[1] = note;
+	sbuf[2] = 127;
+	r = snd_rawmidi_write(midi_out, sbuf, 3);
+	if ( r != 3 ) {
+		printf("snd_rawmidi_write said %li\n", r);
+	}
+	snd_rawmidi_drain(midi_out);
+}
+
+
+static void send_note_off(snd_rawmidi_t *midi_out, int note)
+{
+	unsigned char sbuf[3];
+	ssize_t r;
+	sbuf[0] = 0x8e;
+	sbuf[1] = note;
+	sbuf[2] = 0;
+	r = snd_rawmidi_write(midi_out, sbuf, 3);
+	if ( r != 3 ) {
+		printf("snd_rawmidi_write said %li\n", r);
+	}
+	snd_rawmidi_drain(midi_out);
+}
+
+
+struct led_callback_data
+{
+	int red;
+	int orange;
+	int green;
+	snd_rawmidi_t *midi_out;
+};
+
+
+static int led_handler(const char *path, const char *types, lo_arg **argv,
+                       int argc, lo_message msg, void *vp)
+{
+	struct led_callback_data *cb = vp;
+	if ( strcmp("red", &argv[0]->s) == 0 ) {
+		send_note_on(cb->midi_out, cb->red);
+	} else if ( strcmp("orange", &argv[0]->s) == 0 ) {
+		send_note_on(cb->midi_out, cb->orange);
+	} else if ( strcmp("green", &argv[0]->s) == 0 ) {
+		send_note_on(cb->midi_out, cb->green);
+	} else if ( strcmp("off", &argv[0]->s) == 0 ) {
+
+		/* Usually, turning off any one of the colours turns off the
+		 * LED, regardless of the current colour.  However, the bottom
+		 * left button's LED is weird, I think because it's
+		 * also the "layer" button.  It can only be switched off
+		 * from the same colour.  So, we force it to be red. */
+		if ( cb->red == 12 ) {
+			send_note_on(cb->midi_out, cb->red);
+		}
+		send_note_off(cb->midi_out, cb->red);
+	} else {
+		fprintf(stderr, "Unrecognised LED mode '%s'\n", &argv[0]->s);
+	}
+
+	return 1;
+}
+
+
+static void add_led(lo_server_thread osc_server, snd_rawmidi_t *midi_out,
+                    int led, int red, int orange, int green)
+{
+	char tmp[256];
+	struct led_callback_data *cb;
+
+	cb = malloc(sizeof(struct led_callback_data));
+	if ( cb == NULL ) return;
+
+	cb->midi_out = midi_out;
+	cb->red = red;
+	cb->orange = orange;
+	cb->green = green;
+
+	snprintf(tmp, 255, "/x1k2/leds/%i", led);
+	lo_server_thread_add_method(osc_server, tmp, "s", led_handler, cb);
+}
+
+
+static int flip_position(int i)
+{
+	int x = i % 4;
+	int y = i / 4;
+	y = 7-y;
+	return 1+y*4+x;
+}
+
+
+int main(int argc, char *argv[])
+{
+	int c, r, i;
+	char *dev = NULL;
+	snd_rawmidi_t *midi_in;
+	snd_rawmidi_t *midi_out;
+	lo_server_thread osc_server;
+
+	/* Long options */
+	const struct option longopts[] = {
+		{"help",               0, NULL,               'h'},
+		{"device",             1, NULL,               'd'},
+		{0, 0, NULL, 0}
+	};
+
+	/* Short options */
+	while ((c = getopt_long(argc, argv, "hd:",
+	                        longopts, NULL)) != -1) {
+
+		switch (c) {
+
+			case 'h' :
+			show_help(argv[0]);
+			return 0;
+
+			case 'd':
+			dev = strdup(optarg);
+			break;
+
+			case 0 :
+			break;
+
+			default :
+			return 1;
+
+		}
+
+	}
+
+	if ( dev == NULL ) {
+
+		/* FIXME: Enumerate and select device */
+		dev = strdup("hw:1");
+
+		printf("Found MIDI device: %s\n", dev);
+
+	}
+
+	r = snd_rawmidi_open(&midi_in, &midi_out, dev, SND_RAWMIDI_SYNC);
+	if ( r ) {
+		fprintf(stderr, "Couldn't open MIDI device: %i\n", r);
+		return 1;
+	}
+
+	osc_server = lo_server_thread_new("7771", error_callback);
+	lo_server_thread_start(osc_server);
+
+	for ( i=0; i<32; i++ ) {
+		add_led(osc_server, midi_out, flip_position(i),
+		        i+24, i+60, i+96);
+	}
+	add_led(osc_server, midi_out, 101, 12, 16, 20);
+	add_led(osc_server, midi_out, 102, 15, 19, 23);
+
+	do {
+
+		ssize_t r;
+		char buf[1024];
+
+		r = snd_rawmidi_read(midi_in, buf, 1024);
+		if ( r > 0 ) {
+			printf("got %li\n", r);
+		}
+		usleep(1);
+
+	} while ( 1 );
+
+	snd_rawmidi_drain(midi_in);
+	snd_rawmidi_close(midi_in);
+
+	snd_rawmidi_drain(midi_out);
+	snd_rawmidi_close(midi_out);
+
+	return 0;
+}