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ALSA backend: add raw midi parser

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This commit is contained in:
Robin Gareus 2014-06-02 19:20:04 +02:00
parent 5cd2010c79
commit c79a56a08f
2 changed files with 189 additions and 15 deletions
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149
libs/backends/alsa/alsa_rawmidi.cc
View File

@ -1,5 +1,6 @@
/*
* Copyright (C) 2014 Robin Gareus <robin@gareus.org>
* Copyright (C) 2010 Devin Anderson
*
* 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
@ -335,6 +336,11 @@ retry:
AlsaRawMidiIn::AlsaRawMidiIn (const char *device)
: AlsaRawMidiIO (device, true)
, _event(0,0)
, _unbuffered_bytes(0)
, _total_bytes(0)
, _expected_bytes(0)
, _status_byte(0)
{
}
@ -450,23 +456,136 @@ AlsaRawMidiIn::main_process_thread ()
continue;
}
if (!(data[0] & 0x80)) {
_DEBUGPRINT("AlsaRawMidiIn: invalid midi message.\n");
}
// TODO parse MIDI-events? break on status-bytes
{
ssize_t size = err;
const uint32_t buf_size = sizeof(MidiEventHeader) + size;
if (_rb->write_space() < buf_size) {
_DEBUGPRINT("AlsaRawMidiIn: ring buffer overflow\n");
continue;
}
struct MidiEventHeader h (time, size);
_rb->write ((uint8_t*) &h, sizeof(MidiEventHeader));
_rb->write (data, size);
}
#if 0
queue_event (time, data, err);
#else
parse_events (time, data, err);
#endif
}
_DEBUGPRINT("AlsaRawMidiIn: MIDI IN THREAD STOPPED\n");
return 0;
}
int
AlsaRawMidiIn::queue_event (const uint64_t time, const uint8_t *data, const size_t size) {
const uint32_t buf_size = sizeof(MidiEventHeader) + size;
_event._pending = false;
if (_rb->write_space() < buf_size) {
_DEBUGPRINT("AlsaRawMidiIn: ring buffer overflow\n");
return -1;
}
struct MidiEventHeader h (time, size);
_rb->write ((uint8_t*) &h, sizeof(MidiEventHeader));
_rb->write (data, size);
return 0;
}
void
AlsaRawMidiIn::parse_events (const uint64_t time, const uint8_t *data, const size_t size) {
if (_event._pending) {
if (queue_event (_event._time, _parser_buffer, _event._size)) {
return;
}
}
for (size_t i = 0; i < size; ++i) {
if (process_byte(time, data[i])) {
if (queue_event (_event._time, _parser_buffer, _event._size)) {
return;
}
}
}
}
// based on JackMidiRawInputWriteQueue by Devin Anderson //
bool
AlsaRawMidiIn::process_byte(const uint64_t time, const uint8_t byte)
{
if (byte >= 0xf8) {
// Realtime
if (byte == 0xfd) {
return false;
}
_parser_buffer[0] = byte;
prepare_byte_event(time, byte);
return true;
}
if (byte == 0xf7) {
// Sysex end
if (_status_byte == 0xf0) {
record_byte(byte);
return prepare_buffered_event(time);
}
_total_bytes = 0;
_unbuffered_bytes = 0;
_expected_bytes = 0;
_status_byte = 0;
return false;
}
if (byte >= 0x80) {
// Non-realtime status byte
if (_total_bytes) {
_total_bytes = 0;
_unbuffered_bytes = 0;
}
_status_byte = byte;
switch (byte & 0xf0) {
case 0x80:
case 0x90:
case 0xa0:
case 0xb0:
case 0xe0:
// Note On, Note Off, Aftertouch, Control Change, Pitch Wheel
_expected_bytes = 3;
break;
case 0xc0:
case 0xd0:
// Program Change, Channel Pressure
_expected_bytes = 2;
break;
case 0xf0:
switch (byte) {
case 0xf0:
// Sysex
_expected_bytes = 0;
break;
case 0xf1:
case 0xf3:
// MTC Quarter Frame, Song Select
_expected_bytes = 2;
break;
case 0xf2:
// Song Position
_expected_bytes = 3;
break;
case 0xf4:
case 0xf5:
// Undefined
_expected_bytes = 0;
_status_byte = 0;
return false;
case 0xf6:
// Tune Request
prepare_byte_event(time, byte);
_expected_bytes = 0;
_status_byte = 0;
return true;
}
}
record_byte(byte);
return false;
}
// Data byte
if (! _status_byte) {
// Data bytes without a status will be discarded.
_total_bytes++;
_unbuffered_bytes++;
return false;
}
if (! _total_bytes) {
// Apply running status.
record_byte(_status_byte);
}
record_byte(byte);
return (_total_bytes == _expected_bytes) ? prepare_buffered_event(time) : false;
}

55
libs/backends/alsa/alsa_rawmidi.h
View File

@ -93,6 +93,61 @@ public:
void* main_process_thread ();
size_t recv_event (pframes_t &, uint8_t *, size_t &);
private:
int queue_event (const uint64_t, const uint8_t *, const size_t);
void parse_events (const uint64_t, const uint8_t *, const size_t);
bool process_byte (const uint64_t, const uint8_t);
void record_byte(uint8_t byte) {
if (_total_bytes < sizeof(_parser_buffer)) {
_parser_buffer[_total_bytes] = byte;
} else {
++_unbuffered_bytes;
}
++_total_bytes;
}
void prepare_byte_event(const uint64_t time, const uint8_t byte) {
_parser_buffer[0] = byte;
_event.prepare(time, 1);
}
bool prepare_buffered_event(const uint64_t time) {
const bool result = !_unbuffered_bytes;
if (result) {
_event.prepare(time, _total_bytes);
}
_total_bytes = 0;
_unbuffered_bytes = 0;
if (_status_byte >= 0xf0) {
_expected_bytes = 0;
_status_byte = 0;
}
return result;
}
struct ParserEvent {
uint64_t _time;
size_t _size;
bool _pending;
ParserEvent (const uint64_t time, const size_t size)
: _time(time)
, _size(size)
, _pending(false) {}
void prepare(const uint64_t time, const size_t size) {
_time = time;
_size = size;
_pending = true;
}
} _event;
size_t _unbuffered_bytes;
size_t _total_bytes;
size_t _expected_bytes;
uint8_t _status_byte;
uint8_t _parser_buffer[1024];
};
} // namespace