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consolidate & document Coreaudio midi parser

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This commit is contained in:
Robin Gareus 2015-07-01 18:14:48 +02:00
parent da0ca57539
commit b687ed9339
2 changed files with 32 additions and 26 deletions
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35
libs/backends/coreaudio/coreaudio_backend.cc
View file

@ -17,6 +17,21 @@
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/* use an additional midi message parser
*
* coreaudio does packetize midi. every packet includes a timestamp.
* With any real midi-device with a phyical layer
* 1 packet = 1 event (no concurrent events are possible on a cable)
*
* Howver, some USB-midi keyboards manage to send concurrent events
* which end up in the same packet (eg. 6 byte message: 2 note-on).
*
* An additional parser is needed to separate them
*/
#define USE_MIDI_PARSER
#include <regex.h>
#include <sys/mman.h>
#include <sys/time.h>
@ -105,12 +120,11 @@ CoreAudioBackend::CoreAudioBackend (AudioEngine& e, AudioBackendInfo& info)
, _processed_samples (0)
, _port_change_flag (false)
#ifdef USE_MIDI_PARSER
, _event(0)
, _first_time(true)
, _unbuffered_bytes(0)
, _total_bytes(0)
, _expected_bytes(0)
, _status_byte(0)
, _parser_bytes(0)
#endif
{
_instance_name = s_instance_name;
@ -1719,16 +1733,23 @@ CoreAudioBackend::process_callback (const uint32_t n_samples, const uint64_t hos
#ifndef USE_MIDI_PARSER
midi_event_put((void*)mbuf, time, data, size);
#else
assert (size < 128);// coremidi limit per packet
bool first_time = true; // this would need to be rememberd per port.
for (size_t mb = 0; mb < size; ++mb) {
if (_first_time && !(data[mb] & 0x80)) {
// expect a status byte at the beginning or every Packet
assert (0);
if (first_time && !(data[mb] & 0x80)) {
/* expect a status byte at the beginning or every Packet.
*
* This parser drops messages spanning multiple packets
* (sysex > 127 bytes).
* see also libs/backends/alsa/alsa_rawmidi.cc
* which implements a complete parser per port without this limit.
*/
continue;
}
_first_time = false;
first_time = false;
if (midi_process_byte (data[mb])) {
midi_event_put ((void*)mbuf, time, _parser_buffer, _event._size);
midi_event_put ((void*)mbuf, time, _parser_buffer, _parser_bytes);
}
}
#endif

23
libs/backends/coreaudio/coreaudio_backend.h
View file

@ -445,8 +445,6 @@ class CoreAudioBackend : public AudioBackend {
return NULL;
}
#define USE_MIDI_PARSER
#ifdef USE_MIDI_PARSER
bool midi_process_byte (const uint8_t);
@ -462,13 +460,13 @@ class CoreAudioBackend : public AudioBackend {
void midi_prepare_byte_event (const uint8_t byte) {
_parser_buffer[0] = byte;
_event.prepare(1);
_parser_bytes = 1;
}
bool midi_prepare_buffered_event () {
const bool result = _unbuffered_bytes == 0;
if (result) {
_event.prepare (_total_bytes);
_parser_bytes = _total_bytes;
}
_total_bytes = 0;
_unbuffered_bytes = 0;
@ -479,25 +477,12 @@ class CoreAudioBackend : public AudioBackend {
return result;
}
struct ParserEvent {
size_t _size;
bool _pending;
ParserEvent (const size_t size)
: _size(size)
, _pending(false) {}
void prepare (const size_t size) {
_size = size;
_pending = true;
}
} _event;
bool _first_time;
size_t _unbuffered_bytes;
size_t _total_bytes;
size_t _expected_bytes;
uint8_t _status_byte;
uint8_t _parser_buffer[1024];
uint8_t _parser_buffer[128];
uint8_t _parser_bytes;
#endif
}; // class CoreAudioBackend