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 14namespace 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// } 41class 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