ref: f985cd607c216c7ae058a7d61acaf621227361ed
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; } }