ref: fb615ebd7e57253d9f19a29b22147e822bdd8d5b
dir: /ext/midi/midi_parser.c/
/*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public License
* as published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
* 02111-1307, USA
*/
/* This file orginally taken from, Fluidsynth, Peter Hanappe */
#include "aubio_priv.h"
#include "midi.h"
#include "midi_event.h"
#include "midi_parser.h"
/** aubio_midi_parser_t */
struct _aubio_midi_parser_t {
unsigned char status; /**< Identifies the type of event, that is
currently received ('Noteon', 'Pitch Bend'
etc). */
unsigned char channel; /**< The channel of the event that is received
(in case of a channel event) */
unsigned int nr_bytes; /**< How many bytes have been read for the
current event? */
unsigned int nr_bytes_total;/**< How many bytes does the current event
type include? */
unsigned short p[AUBIO_MIDI_PARSER_MAX_PAR]; /**< The parameters */
aubio_midi_event_t event; /**< The event, that is returned to the
MIDI driver. */
};
/** new_aubio_midi_parser */
aubio_midi_parser_t* new_aubio_midi_parser()
{
aubio_midi_parser_t* parser;
parser = AUBIO_NEW(aubio_midi_parser_t);
if (parser == NULL) {
AUBIO_ERR("Out of memory");
return NULL;
}
/* As long as the status is 0, the parser won't do anything -> no need to
* initialize all the fields. */
parser->status = 0;
return parser;
}
/** del_aubio_midi_parser */
int del_aubio_midi_parser(aubio_midi_parser_t* parser)
{
AUBIO_FREE(parser);
return AUBIO_OK;
}
/** aubio_midi_parser_parse
*
* The MIDI byte stream is fed into the parser, one byte at a time.
* As soon as the parser has recognized an event, it will return it.
* Otherwise it returns NULL.
*/
aubio_midi_event_t* aubio_midi_parser_parse(aubio_midi_parser_t* parser,
unsigned char c)
{
/*********************************************************************/
/* 'Process' system real-time messages */
/*********************************************************************/
/* There are not too many real-time messages that are of interest here.
* They can occur anywhere, even in the middle of a noteon message!
* Real-time range: 0xF8 .. 0xFF
* Note: Real-time does not affect (running) status.
*/
if (c >= 0xF8){
if (c == MIDI_SYSTEM_RESET){
parser->event.type = c;
parser->status = 0; /* clear the status */
return &parser->event;
};
return NULL;
};
/*********************************************************************/
/* 'Process' system common messages (again, just skip them) */
/*********************************************************************/
/* There are no system common messages that are of interest here.
* System common range: 0xF0 .. 0xF7
*/
if (c > 0xF0){
/* MIDI specs say: To ignore a non-real-time message, just discard all data
* up to the next status byte. And our parser will ignore data that is
* received without a valid status.
* Note: system common cancels running status. */
parser->status = 0;
return NULL;
};
/*********************************************************************/
/* Process voice category messages: */
/*********************************************************************/
/* Now that we have handled realtime and system common messages, only
* voice messages are left.
* Only a status byte has bit # 7 set.
* So no matter the status of the parser (in case we have lost sync),
* as soon as a byte >= 0x80 comes in, we are dealing with a status byte
* and start a new event.
*/
if (c & 0x80){
parser->channel = c & 0x0F;
parser->status = c & 0xF0;
/* The event consumes x bytes of data... (subtract 1 for the status
* byte) */
parser->nr_bytes_total=aubio_midi_event_length(parser->status)-1;
/* of which we have read 0 at this time. */
parser->nr_bytes = 0;
return NULL;
};
/*********************************************************************/
/* Process data */
/*********************************************************************/
/* If we made it this far, then the received char belongs to the data
* of the last event. */
if (parser->status == 0){
/* We are not interested in the event currently received.
* Discard the data. */
return NULL;
};
/* Store the first couple of bytes */
if (parser->nr_bytes < AUBIO_MIDI_PARSER_MAX_PAR){
parser->p[parser->nr_bytes]=c;
};
parser->nr_bytes++;
/* Do we still need more data to get this event complete? */
if (parser->nr_bytes < parser->nr_bytes_total){
return NULL;
};
/*********************************************************************/
/* Send the event */
/*********************************************************************/
/* The event is ready-to-go. About 'running status':
*
* The MIDI protocol has a built-in compression mechanism. If several similar
* events are sent in-a-row, for example note-ons, then the event type is
* only sent once. For this case, the last event type (status) is remembered.
* We simply keep the status as it is, just reset the parameter counter. If
* another status byte comes in, it will overwrite the status.
*/
parser->event.type = parser->status;
parser->event.channel = parser->channel;
parser->nr_bytes = 0; /* Related to running status! */
switch (parser->status){
case NOTE_OFF:
case NOTE_ON:
case KEY_PRESSURE:
case CONTROL_CHANGE:
case PROGRAM_CHANGE:
case CHANNEL_PRESSURE:
parser->event.param1 = parser->p[0]; /* For example key number */
parser->event.param2 = parser->p[1]; /* For example velocity */
break;
case PITCH_BEND:
/* Pitch-bend is transmitted with 14-bit precision. */
/* Note: '|' does here the same as '+' (no common bits),
* but might be faster */
parser->event.param1 = ((parser->p[1] << 7) | parser->p[0]);
break;
default:
/* Unlikely */
return NULL;
};
return &parser->event;
};
/* Taken from Nagano Daisuke's USB-MIDI driver */
static int remains_f0f6[] = {
0, /* 0xF0 */
2, /* 0XF1 */
3, /* 0XF2 */
2, /* 0XF3 */
2, /* 0XF4 (Undefined by MIDI Spec, and subject to change) */
2, /* 0XF5 (Undefined by MIDI Spec, and subject to change) */
1 /* 0XF6 */
};
static int remains_80e0[] = {
3, /* 0x8X Note Off */
3, /* 0x9X Note On */
3, /* 0xAX Poly-key pressure */
3, /* 0xBX Control Change */
2, /* 0xCX Program Change */
2, /* 0xDX Channel pressure */
3 /* 0xEX PitchBend Change */
};
/** Returns the length of the MIDI message starting with c.
*
* Taken from Nagano Daisuke's USB-MIDI driver */
int aubio_midi_event_length(unsigned char event){
if ( event < 0xf0 ) {
return remains_80e0[((event-0x80)>>4)&0x0f];
} else if ( event < 0xf7 ) {
return remains_f0f6[event-0xf0];
} else {
return 1;
}
}