1 // Copyright 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef MEDIA_MIDI_MIDI_MESSAGE_QUEUE_H_ 6 #define MEDIA_MIDI_MIDI_MESSAGE_QUEUE_H_ 7 8 #include <deque> 9 #include <vector> 10 11 #include "base/basictypes.h" 12 #include "media/base/media_export.h" 13 14 namespace media { 15 16 // A simple message splitter for possibly unsafe/corrupted MIDI data stream. 17 // This class allows you to: 18 // - maintain fragmented MIDI message. 19 // - skip any invalid data sequence. 20 // - reorder MIDI messages so that "System Real Time Message", which can be 21 // inserted at any point of the byte stream, is placed at the boundary of 22 // complete MIDI messages. 23 // - (Optional) reconstruct complete MIDI messages from data stream where 24 // MIDI status byte is abbreviated (a.k.a. "running status"). 25 // 26 // Example (pseudo message loop): 27 // MidiMessageQueue queue(true); // true to support "running status" 28 // while (true) { 29 // if (is_incoming_midi_data_available()) { 30 // std::vector<uint8> incoming_data; 31 // read_incoming_midi_data(&incoming_data) 32 // queue.Add(incoming_data); 33 // } 34 // while (true) { 35 // std::vector<uint8> next_message; 36 // queue.Get(&next_message); 37 // if (!next_message.empty()) 38 // dispatch(next_message); 39 // } 40 // } 41 class MEDIA_EXPORT MidiMessageQueue { 42 public: 43 // Initializes the queue. Set true to |allow_running_status| to enable 44 // "MIDI running status" reconstruction. 45 explicit MidiMessageQueue(bool allow_running_status); 46 ~MidiMessageQueue(); 47 48 // Enqueues |data| to the internal buffer. 49 void Add(const std::vector<uint8>& data); 50 void Add(const uint8* data, size_t length); 51 52 // Fills the next complete MIDI message into |message|. If |message| is 53 // not empty, the data sequence falls into one of the following types of 54 // MIDI message. 55 // - Single "Channel Voice Message" (w/o "System Real Time Messages") 56 // - Single "Channel Mode Message" (w/o "System Real Time Messages") 57 // - Single "System Exclusive Message" (w/o "System Real Time Messages") 58 // - Single "System Common Message" (w/o "System Real Time Messages") 59 // - Single "System Real Time message" 60 // |message| is empty if there is no complete MIDI message any more. 61 void Get(std::vector<uint8>* message); 62 63 private: 64 std::deque<uint8> queue_; 65 std::vector<uint8> next_message_; 66 const bool allow_running_status_; 67 DISALLOW_COPY_AND_ASSIGN(MidiMessageQueue); 68 }; 69 70 } // namespace media 71 72 #endif // MEDIA_MIDI_MIDI_MESSAGE_QUEUE_H_ 73