common/JackMidiPort.cpp

   1 /*
   2 Copyright (C) 2007 Dmitry Baikov
   3 Original JACK MIDI implementation Copyright (C) 2004 Ian Esten
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18
  19 */
  20
  21 #include "JackError.h"
  22 #include "JackPortType.h"
  23 #include "JackMidiPort.h"
  24 #include <assert.h>
  25 #include <string.h>
  26
  27 namespace Jack
  28 {
  29
  30 SERVER_EXPORT void JackMidiBuffer::Reset(jack_nframes_t nframes)
  31 {
  32     /* This line ate 1 hour of my life... dsbaikov */
  33     this->nframes = nframes;
  34     write_pos = 0;
  35     event_count = 0;
  36     lost_events = 0;
  37     mix_index = 0;
  38 }
  39
  40 SERVER_EXPORT jack_shmsize_t JackMidiBuffer::MaxEventSize() const
  41 {
  42     assert (((jack_shmsize_t) - 1) < 0); // jack_shmsize_t should be signed
  43     jack_shmsize_t left = buffer_size - (sizeof(JackMidiBuffer) + sizeof(JackMidiEvent) * (event_count + 1) + write_pos);
  44     if (left < 0)
  45         return 0;
  46     if (left <= JackMidiEvent::INLINE_SIZE_MAX)
  47         return JackMidiEvent::INLINE_SIZE_MAX;
  48     return left;
  49 }
  50
  51 SERVER_EXPORT jack_midi_data_t* JackMidiBuffer::ReserveEvent(jack_nframes_t time, jack_shmsize_t size)
  52 {
  53     jack_shmsize_t space = MaxEventSize();
  54     if (space == 0 || size > space) {
  55         jack_error("JackMidiBuffer::ReserveEvent - the buffer does not have "
  56                    "enough room to enqueue a %lu byte event", size);
  57         lost_events++;
  58         return 0;
  59     }
  60     JackMidiEvent* event = &events[event_count++];
  61     event->time = time;
  62     event->size = size;
  63     if (size <= JackMidiEvent::INLINE_SIZE_MAX)
  64         return event->data;
  65
  66     write_pos += size;
  67     event->offset = buffer_size - write_pos;
  68     return (jack_midi_data_t*)this + event->offset;
  69 }
  70
  71 static void MidiBufferInit(void* buffer, size_t buffer_size, jack_nframes_t nframes)
  72 {
  73     JackMidiBuffer* midi = (JackMidiBuffer*)buffer;
  74     midi->magic = JackMidiBuffer::MAGIC;
  75     /* Since port buffer has actually always BUFFER_SIZE_MAX frames, we can safely use all the size */
  76     midi->buffer_size = BUFFER_SIZE_MAX * sizeof(jack_default_audio_sample_t);
  77     midi->Reset(nframes);
  78 }
  79
  80 /*
  81  * The mixdown function below, is a simplest (read slowest) implementation possible.
  82  * But, since it is unlikely that it will mix many buffers with many events,
  83  * it should perform quite good.
  84  * More efficient (and possibly, fastest possible) implementation (it exists),
  85  * using calendar queue algorithm is about 3 times bigger, and uses alloca().
  86  * So, let's listen to D.Knuth about premature optimisation, a leave the current
  87  * implementation as is, until it is proved to be a bottleneck.
  88  * Dmitry Baikov.
  89  */
  90 static void MidiBufferMixdown(void* mixbuffer, void** src_buffers, int src_count, jack_nframes_t nframes)
  91 {
  92     JackMidiBuffer* mix = static_cast<JackMidiBuffer*>(mixbuffer);
  93     if (!mix->IsValid()) {
  94         jack_error("Jack::MidiBufferMixdown - invalid mix buffer");
  95         return;
  96     }
  97     mix->Reset(nframes);
  98
  99     int event_count = 0;
 100     for (int i = 0; i < src_count; ++i) {
 101         JackMidiBuffer* buf = static_cast<JackMidiBuffer*>(src_buffers[i]);
 102         if (!buf->IsValid()) {
 103             jack_error("Jack::MidiBufferMixdown - invalid source buffer");
 104             return;
 105         }
 106         buf->mix_index = 0;
 107         event_count += buf->event_count;
 108         mix->lost_events += buf->lost_events;
 109     }
 110
 111     int events_done;
 112     for (events_done = 0; events_done < event_count; ++events_done) {
 113         JackMidiBuffer* next_buf = 0;
 114         JackMidiEvent* next_event = 0;
 115
 116         // find the earliest event
 117         for (int i = 0; i < src_count; ++i) {
 118             JackMidiBuffer* buf = static_cast<JackMidiBuffer*>(src_buffers[i]);
 119             if (buf->mix_index >= buf->event_count)
 120                 continue;
 121             JackMidiEvent* e = &buf->events[buf->mix_index];
 122             if (!next_event || e->time < next_event->time) {
 123                 next_event = e;
 124                 next_buf = buf;
 125             }
 126         }
 127         assert(next_event != 0);
 128
 129         // write the event
 130         jack_midi_data_t* dest = mix->ReserveEvent(next_event->time, next_event->size);
 131         if (!dest)
 132             break;
 133         memcpy(dest, next_event->GetData(next_buf), next_event->size);
 134         next_buf->mix_index++;
 135     }
 136     mix->lost_events += event_count - events_done;
 137 }
 138
 139 static size_t MidiBufferSize()
 140 {
 141     return BUFFER_SIZE_MAX * sizeof(jack_default_audio_sample_t);
 142 }
 143
 144 const JackPortType gMidiPortType =
 145 {
 146     JACK_DEFAULT_MIDI_TYPE,
 147     MidiBufferSize,
 148     MidiBufferInit,
 149     MidiBufferMixdown
 150 };
 151
 152 } // namespace Jack