1 files changed, 258 insertions, 0 deletions
diff --git a/src/tools/midifile.c b/src/tools/midifile.c
new file mode 100644
index 00000000..30457c51
--- /dev/null
+++ b/src/tools/midifile.c
@@ -0,0 +1,258 @@
+/* PipeWire
+ *
+ * Copyright © 2020 Wim Taymans
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <errno.h>
+
+#include "midifile.h"
+
+#define DEFAULT_TEMPO	500000	/* 500ms per quarter note (120 BPM) is the default */
+
+static inline uint16_t parse_be16(const uint8_t *in)
+{
+	return (in[0] << 8) | in[1];
+}
+
+static inline uint32_t parse_be32(const uint8_t *in)
+{
+	return (in[0] << 24) | (in[1] << 16) | (in[2] << 8) | in[3];
+}
+
+static int read_mthd(struct midi_file *mf)
+{
+	uint8_t buffer[14];
+	int res;
+
+	if ((res = mf->events->read(mf->data, mf->offset, buffer, 14)) != 14)
+		return res < 0 ? res : -EIO;
+
+	if (memcmp(buffer, "MThd", 4))
+		return -EIO;
+
+	mf->size = parse_be32(buffer + 4);
+	mf->format = parse_be16(buffer + 8);
+	mf->ntracks = parse_be16(buffer + 10);
+	mf->division = parse_be16(buffer + 12);
+	mf->offset += 14;
+	return 0;
+}
+
+int midi_file_open(struct midi_file *mf, int mode,
+		const struct midi_events *events, void *data)
+{
+	int res;
+
+	spa_zero(*mf);
+
+	mf->events = events;
+	mf->data = data;
+
+	if ((res = read_mthd(mf)) < 0)
+		return res;
+
+	spa_list_init(&mf->tracks);
+	mf->tick = 0;
+	mf->tempo = DEFAULT_TEMPO;
+
+	return 0;
+}
+
+int midi_file_close(struct midi_file *mf)
+{
+	return 0;
+}
+
+static int read_mtrk(struct midi_file *mf, struct midi_track *track)
+{
+	uint8_t buffer[8];
+	int res;
+
+	if ((res = mf->events->read(mf->data, mf->offset, buffer, 8)) != 8)
+		return res < 0 ? res : -EIO;
+
+	if (memcmp(buffer, "MTrk", 4))
+		return -EIO;
+
+	track->start = mf->offset+8;
+	track->offset = 0;
+	track->size = parse_be32(buffer + 4);
+	mf->offset += track->size + 8;
+	return 0;
+}
+
+static int parse_varlen(struct midi_file *mf, struct midi_track *tr, uint32_t *result)
+{
+	uint32_t value;
+	uint8_t buffer[1];
+	int i, res;
+
+	value = 0;
+	for (i = 0; i < 4; i++) {
+		if (tr->offset >= tr->size) {
+			tr->eof = true;
+			break;
+		}
+
+		if ((res = mf->events->read(mf->data, tr->start + tr->offset, buffer, 1)) != 1)
+			return res < 0 ? res : -EIO;
+
+		tr->offset++;
+
+		value = (value << 7) | ((buffer[0]) & 0x7f);
+		if ((buffer[0] & 0x80) == 0)
+			break;
+	}
+	*result = value;
+	return 0;
+}
+
+
+static int peek_event(struct midi_file *mf, struct midi_track *tr, struct midi_event *event)
+{
+	uint8_t buffer[4], status;
+	uint32_t size = 0, start;
+	int res;
+
+	if (tr->eof || tr->offset > tr->size)
+		return -EIO;
+
+	if ((res = mf->events->read(mf->data, tr->start + tr->offset, buffer, 1)) != 1)
+		return res < 0 ? res : -EIO;
+
+	event->track = tr;
+	event->tick = tr->tick;
+	start = event->offset = tr->offset;
+
+	status = buffer[0];
+	if ((status & 0x80) == 0) {
+		status = tr->running_status;
+	} else {
+		tr->running_status = status;
+		event->offset++;
+	}
+
+	event->status = status;
+
+	tr->offset++;
+
+	if (status < 0xf0) {
+		size++;
+		if (status < 0xc0 || status >= 0xe0)
+			size++;
+	} else {
+		if (status == 0xff) {
+			if ((res = mf->events->read(mf->data, tr->start + tr->offset, buffer, 1)) != 1)
+				return res < 0 ? res : -EIO;
+
+			tr->offset++;
+
+			if ((res = parse_varlen(mf, tr, &size)) < 0)
+				return res;
+
+			event->meta = buffer[0];
+			event->offset = tr->offset;
+
+			switch (event->meta) {
+			case 0x2f:
+				tr->eof = true;
+				break;
+			case 0x51:
+				if (size < 3)
+					break;
+
+				if ((res = mf->events->read(mf->data, tr->start + tr->offset, buffer, 3)) != 3)
+					return res < 0 ? res : -EIO;
+
+				mf->tempo = (buffer[0]<<16) | (buffer[1]<<8) | buffer[2];
+				break;
+			}
+
+		} else if (status == 0xf0 || status == 0xf7) {
+			if ((res = parse_varlen(mf, tr, &size)) < 0)
+				return res;
+			event->offset = tr->offset;
+		} else {
+			return -EIO;
+		}
+	}
+	tr->offset = start;
+
+	event->offset += tr->start;
+	event->size = size;
+
+	return 0;
+}
+
+int midi_file_add_track(struct midi_file *mf, struct midi_track *track)
+{
+	int res;
+	uint32_t delta_time;
+
+	if ((res = read_mtrk(mf, track)) < 0)
+		return res;
+
+	if ((res = parse_varlen(mf, track, &delta_time)) < 0)
+		return res;
+
+	track->tick = delta_time;
+	spa_list_init(&track->events);
+	spa_list_append(&mf->tracks, &track->link);
+
+	return 0;
+
+}
+int midi_file_peek_event(struct midi_file *mf, struct midi_event *event)
+{
+	struct midi_track *tr, *found = NULL;
+
+	spa_list_for_each(tr, &mf->tracks, link) {
+		if (tr->eof)
+			continue;
+		if (found == NULL || tr->tick < found->tick)
+			found = tr;
+	}
+	if (found == NULL)
+		return -EIO;
+
+	return peek_event(mf, found, event);
+}
+
+int midi_file_consume_event(struct midi_file *mf, struct midi_event *event)
+{
+	struct midi_track *tr = event->track;
+	uint32_t delta_time;
+	int res;
+
+	tr->offset = event->offset - tr->start + event->size;
+	if ((res = parse_varlen(mf, tr, &delta_time)) < 0)
+		return res;
+	tr->tick += delta_time;
+	return 0;
+}
+
+int midi_file_add_event(struct midi_file *mf, struct midi_track *track, struct midi_event *event)
+{
+	spa_list_append(&track->events, &event->link);
+	return 0;
+}
+