common/JackMidiAsyncQueue.h

   1 /*
   2 Copyright (C) 2010 Devin Anderson
   3
   4 This program is free software; you can redistribute it and/or modify
   5 it under the terms of the GNU Lesser General Public License as published by
   6 the Free Software Foundation; either version 2.1 of the License, or
   7 (at your option) any later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU Lesser General Public License for more details.
  13
  14 You should have received a copy of the GNU Lesser General Public License
  15 along with this program; if not, write to the Free Software
  16 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17
  18 */
  19
  20 #ifndef __JackMidiAsyncQueue__
  21 #define __JackMidiAsyncQueue__
  22
  23 #include "JackMidiPort.h"
  24 #include "JackMidiReadQueue.h"
  25 #include "JackMidiWriteQueue.h"
  26 #include "ringbuffer.h"
  27
  28 namespace Jack {
  29
  30     /**
  31      * This is a MIDI message queue designed to allow one thread to pass MIDI
  32      * messages to another thread (though it can also be used to buffer events
  33      * internally).  This is especially useful if the MIDI API you're
  34      * attempting to interface with doesn't provide the ability to schedule
  35      * MIDI events ahead of time and/or has blocking send/receive calls, as it
  36      * allows a separate thread to handle input/output while the JACK process
  37      * thread copies events from a MIDI buffer to this queue, or vice versa.
  38      */
  39
  40     class SERVER_EXPORT JackMidiAsyncQueue:
  41         public JackMidiReadQueue, public JackMidiWriteQueue {
  42
  43     private:
  44
  45         static const size_t INFO_SIZE =
  46             sizeof(jack_nframes_t) + sizeof(size_t);
  47
  48         jack_ringbuffer_t *byte_ring;
  49         jack_midi_data_t *data_buffer;
  50         jack_midi_event_t dequeue_event;
  51         jack_ringbuffer_t *info_ring;
  52         size_t max_bytes;
  53
  54     public:
  55
  56         using JackMidiWriteQueue::EnqueueEvent;
  57
  58         /**
  59          * Creates a new asynchronous MIDI message queue.  The queue can store
  60          * up to `max_messages` MIDI messages and up to `max_bytes` of MIDI
  61          * data before it starts rejecting messages.
  62          */
  63
  64         JackMidiAsyncQueue(size_t max_bytes=4096, size_t max_messages=1024);
  65
  66         virtual
  67         ~JackMidiAsyncQueue();
  68
  69         /**
  70          * Dequeues and returns a MIDI event.  Returns '0' if there are no MIDI
  71          * events available.  This method may be overridden.
  72          */
  73
  74         virtual jack_midi_event_t *
  75         DequeueEvent();
  76
  77         /**
  78          * Enqueues the MIDI event specified by the arguments.  The return
  79          * value indiciates whether or not the event was successfully enqueued.
  80          * This method may be overridden.
  81          */
  82
  83         virtual EnqueueResult
  84         EnqueueEvent(jack_nframes_t time, size_t size,
  85                      jack_midi_data_t *buffer);
  86
  87         /**
  88          * Returns the maximum size event that can be enqueued right *now*.
  89          */
  90
  91         size_t
  92         GetAvailableSpace();
  93
  94     };
  95
  96 }
  97
  98 #endif