JackMidiPort.cpp
/*
Copyright (C) 2007 Dmitry Baikov
Original JACK MIDI implementation Copyright (C) 2004 Ian Esten
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser 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.
*/
#include "JackError.h"
#include "JackPortType.h"
#include "JackMidiPort.h"
#include <assert.h>
#include <string.h>
namespace Jack
{
SERVER_EXPORT void JackMidiBuffer::Reset(jack_nframes_t nframes)
{
/* This line ate 1 hour of my life... dsbaikov */
this->nframes = nframes;
write_pos = 0;
event_count = 0;
lost_events = 0;
}
SERVER_EXPORT jack_shmsize_t JackMidiBuffer::MaxEventSize() const
{
assert (((jack_shmsize_t) - 1) < 0); // jack_shmsize_t should be signed
jack_shmsize_t left = buffer_size - (sizeof(JackMidiBuffer) + sizeof(JackMidiEvent) * (event_count + 1) + write_pos);
if (left < 0) {
return 0;
}
if (left <= JackMidiEvent::INLINE_SIZE_MAX) {
return JackMidiEvent::INLINE_SIZE_MAX;
}
return left;
}
SERVER_EXPORT jack_midi_data_t* JackMidiBuffer::ReserveEvent(jack_nframes_t time, jack_shmsize_t size)
{
jack_shmsize_t space = MaxEventSize();
if (space == 0 || size > space) {
jack_error("JackMidiBuffer::ReserveEvent - the buffer does not have "
"enough room to enqueue a %lu byte event", size);
lost_events++;
return 0;
}
JackMidiEvent* event = &events[event_count++];
event->time = time;
event->size = size;
if (size <= JackMidiEvent::INLINE_SIZE_MAX) {
return event->data;
}
write_pos += size;
event->offset = buffer_size - write_pos;
return (jack_midi_data_t*)this + event->offset;
}
void MidiBufferInit(void* buffer, size_t buffer_size, jack_nframes_t nframes)
{
JackMidiBuffer* midi = (JackMidiBuffer*)buffer;
midi->magic = JackMidiBuffer::MAGIC;
/* Since port buffer has actually always BUFFER_SIZE_MAX frames, we can safely use all the size */
midi->buffer_size = BUFFER_SIZE_MAX * sizeof(jack_default_audio_sample_t);
midi->Reset(nframes);
}
/*
* The mixdown function below, is a simplest (read slowest) implementation possible.
* But, since it is unlikely that it will mix many buffers with many events,
* it should perform quite good.
* More efficient (and possibly, fastest possible) implementation (it exists),
* using calendar queue algorithm is about 3 times bigger, and uses alloca().
* So, let's listen to D.Knuth about premature optimisation, a leave the current
* implementation as is, until it is proved to be a bottleneck.
* Dmitry Baikov.
*/
static void MidiBufferMixdown(void* mixbuffer, void** src_buffers, int src_count, jack_nframes_t nframes)
{
JackMidiBuffer* mix = static_cast<JackMidiBuffer*>(mixbuffer);
if (!mix->IsValid()) {
jack_error("Jack::MidiBufferMixdown - invalid mix buffer");
return;
}
mix->Reset(nframes);
uint32_t mix_index[src_count];
int event_count = 0;
for (int i = 0; i < src_count; ++i) {
JackMidiBuffer* buf = static_cast<JackMidiBuffer*>(src_buffers[i]);
if (!buf->IsValid()) {
jack_error("Jack::MidiBufferMixdown - invalid source buffer");
return;
}
mix_index[i] = 0;
event_count += buf->event_count;
mix->lost_events += buf->lost_events;
}
int events_done;
for (events_done = 0; events_done < event_count; ++events_done) {
JackMidiBuffer* next_buf = 0;
JackMidiEvent* next_event = 0;
uint32_t next_buf_index = 0;
// find the earliest event
for (int i = 0; i < src_count; ++i) {
JackMidiBuffer* buf = static_cast<JackMidiBuffer*>(src_buffers[i]);
if (mix_index[i] >= buf->event_count)
continue;
JackMidiEvent* e = &buf->events[mix_index[i]];
if (!next_event || e->time < next_event->time) {
next_event = e;
next_buf = buf;
next_buf_index = i;
}
}
assert(next_event != 0);
// write the event
jack_midi_data_t* dest = mix->ReserveEvent(next_event->time, next_event->size);
if (!dest) break;
memcpy(dest, next_event->GetData(next_buf), next_event->size);
mix_index[next_buf_index]++;
}
mix->lost_events += event_count - events_done;
}
static size_t MidiBufferSize()
{
return BUFFER_SIZE_MAX * sizeof(jack_default_audio_sample_t);
}
const JackPortType gMidiPortType =
{
JACK_DEFAULT_MIDI_TYPE,
MidiBufferSize,
MidiBufferInit,
MidiBufferMixdown
};
} // namespace Jack
Jack
Definition: JackAC3Encoder.cpp:30
jack_error
SERVER_EXPORT void jack_error(const char *fmt,...)
Definition: JackError.cpp:92
Jack::JackMidiBuffer::write_pos
jack_shmsize_t write_pos
data write position from the end of the buffer.
Definition: JackMidiPort.h:82