jack2/linux/alsa/midi_unpack.h

/*
 * Copyright (c) 2006,2007 Dmitry S. Baikov
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#ifndef __jack_midi_unpack_h__
#define __jack_midi_unpack_h__

enum {
	MIDI_UNPACK_MAX_MSG = 1024
};

typedef struct {
	int pos, need, size;
	unsigned char data[MIDI_UNPACK_MAX_MSG];
} midi_unpack_t;

static inline
void midi_unpack_init(midi_unpack_t *u)
{
	u->pos = 0;
	u->size = sizeof(u->data);
	u->need = u->size;
}

static inline
void midi_unpack_reset(midi_unpack_t *u)
{
	u->pos = 0;
	u->need = u->size;
}

static const unsigned char midi_voice_len[] = {
	3, /*0x80 Note Off*/
	3, /*0x90 Note On*/
	3, /*0xA0 Aftertouch*/
	3, /*0xB0 Control Change*/
	2, /*0xC0 Program Change*/
	2, /*0xD0 Channel Pressure*/
	3, /*0xE0 Pitch Wheel*/
	1  /*0xF0 System*/
};

static const unsigned char midi_system_len[] = {
	0, /*0xF0 System Exclusive Start*/
	2, /*0xF1 MTC Quarter Frame*/
	3, /*0xF2 Song Postion*/
	2, /*0xF3 Song Select*/
	0, /*0xF4 undefined*/
	0, /*0xF5 undefined*/
	1, /*0xF6 Tune Request*/
	1  /*0xF7 System Exlusive End*/
};

static
int midi_unpack_buf(midi_unpack_t *buf, const unsigned char *data, int len, void *jack_port_buf, jack_nframes_t time)
{
	int i;
	for (i=0; i<len; ++i)
	{
		const unsigned char byte = data[i];
		if (byte >= 0xF8) // system realtime
		{
			jack_midi_event_write(jack_port_buf, time, &data[i], 1);
			//printf("midi_unpack: written system relatime event\n");
			//midi_input_write(in, &data[i], 1);
		}
		else if (byte < 0x80) // data
		{
			assert (buf->pos < buf->size);
			buf->data[buf->pos++] = byte;
		}
		else if (byte < 0xF0) // voice
		{
			assert (byte >= 0x80 && byte < 0xF0);
			//buf->need = ((byte|0x0F) == 0xCF || (byte|0x0F)==0xDF) ? 2 : 3;
			buf->need = midi_voice_len[(byte-0x80)>>4];
			buf->data[0] = byte;
			buf->pos = 1;
		}
		else if (byte == 0xF7) // sysex end
		{
			assert (buf->pos < buf->size);
			buf->data[buf->pos++] = byte;
			buf->need = buf->pos;
		}
		else
		{
			assert (byte >= 0xF0 && byte < 0xF8);
			buf->pos = 1;
			buf->data[0] = byte;
			buf->need = midi_system_len[byte - 0xF0];
			if (!buf->need)
				buf->need = buf->size;
		}
		if (buf->pos == buf->need)
		{
			// TODO: deal with big sysex'es (they are silently dropped for now)
			if (buf->data[0] >= 0x80 || (buf->data[0]==0xF0 && buf->data[buf->pos-1] == 0xF7)) {
				/* convert Note On with velocity 0 to Note Off */
				if ((buf->data[0] & 0xF0) == 0x90 && buf->data[2] == 0) {
					// we use temp array here to keep running status sync
					jack_midi_data_t temp[3] = { 0x80, 0, 0x40 };
					temp[0] |= buf->data[0] & 0x0F;
					temp[1] = buf->data[1];
					jack_midi_event_write(jack_port_buf, time, temp, 3);
				} else
					jack_midi_event_write(jack_port_buf, time, &buf->data[0], buf->pos);
				//printf("midi_unpack: written %d-byte event\n", buf->pos);
				//midi_input_write(in, &buf->data[0], buf->pos);
			}
			/* keep running status */
			if (buf->data[0] >= 0x80 && buf->data[0] < 0xF0)
				buf->pos = 1;
			else
			{
				buf->pos = 0;
				buf->need = buf->size;
			}
		}
	}
	assert (i==len);
	return i;
}

#endif /* __jack_midi_unpack_h__ */