common/JackMidiPort.h

   1 /*
   2 Copyright (C) 2007 Dmitry Baikov
   3 Original JACK MIDI API 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 #ifndef __JackMidiPort__
  22 #define __JackMidiPort__
  23
  24 #include "types.h"
  25 #include "JackConstants.h"
  26 #include <stddef.h>
  27
  28 /** Type for raw event data contained in @ref jack_midi_event_t. */
  29 typedef unsigned char jack_midi_data_t;
  30
  31 /** A Jack MIDI event. */
  32 struct jack_midi_event_t
  33 {
  34     jack_nframes_t    time;   /**< Sample index at which event is valid */
  35     size_t            size;   /**< Number of bytes of data in \a buffer */
  36     jack_midi_data_t *buffer; /**< Raw MIDI data */
  37 };
  38
  39 /** A Jack MIDI port type. */
  40 #define JACK_DEFAULT_MIDI_TYPE "8 bit raw midi"
  41
  42 namespace Jack
  43 {
  44
  45 struct JackMidiEvent
  46 {
  47     // Most MIDI events are < 4 bytes in size, so we can save a lot, storing them inplace.
  48     enum { INLINE_SIZE_MAX = sizeof(jack_shmsize_t) };
  49
  50     uint32_t time;
  51     jack_shmsize_t size;
  52     union {
  53         jack_shmsize_t   offset;
  54         jack_midi_data_t data[INLINE_SIZE_MAX];
  55     };
  56
  57     jack_midi_data_t* GetData(void* buffer)
  58     {
  59         if (size <= INLINE_SIZE_MAX)
  60             return data;
  61         else
  62             return (jack_midi_data_t*)buffer + offset;
  63     }
  64 };
  65
  66 /*
  67  * To store events with arbitrarily sized payload, but still have O(1) indexed access
  68  * we use a trick here:
  69  * Events are stored in an linear array from the beginning of the buffer,
  70  * but their data (if not inlined) is stored from the end of the same buffer.
  71  */
  72
  73 struct JackMidiBuffer
  74 {
  75     enum { MAGIC = 0x900df00d };
  76
  77     uint32_t magic;
  78     jack_shmsize_t buffer_size;
  79     jack_nframes_t nframes;
  80     jack_shmsize_t write_pos; //!< data write position from the end of the buffer.
  81     uint32_t event_count;
  82     uint32_t lost_events;
  83     uint32_t mix_index;
  84
  85     JackMidiEvent events[0];
  86
  87     int IsValid() const
  88     {
  89         return magic == MAGIC;
  90     }
  91     void Reset(jack_nframes_t nframes);
  92     jack_shmsize_t MaxEventSize() const;
  93
  94     // checks only size constraints.
  95     jack_midi_data_t* ReserveEvent(jack_nframes_t time, jack_shmsize_t size);
  96 };
  97
  98 } // namespace Jack
  99
 100 #endif