// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_MIDI_MIDI_MESSAGE_QUEUE_H_
#define MEDIA_MIDI_MIDI_MESSAGE_QUEUE_H_
#include <deque>
#include <vector>
#include "base/basictypes.h"
#include "media/base/media_export.h"
namespace media {
// A simple message splitter for possibly unsafe/corrupted MIDI data stream.
// This class allows you to:
// - maintain fragmented MIDI message.
// - skip any invalid data sequence.
// - reorder MIDI messages so that "System Real Time Message", which can be
// inserted at any point of the byte stream, is placed at the boundary of
// complete MIDI messages.
// - (Optional) reconstruct complete MIDI messages from data stream where
// MIDI status byte is abbreviated (a.k.a. "running status").
//
// Example (pseudo message loop):
// MidiMessageQueue queue(true); // true to support "running status"
// while (true) {
// if (is_incoming_midi_data_available()) {
// std::vector<uint8> incoming_data;
// read_incoming_midi_data(&incoming_data)
// queue.Add(incoming_data);
// }
// while (true) {
// std::vector<uint8> next_message;
// queue.Get(&next_message);
// if (!next_message.empty())
// dispatch(next_message);
// }
// }
class MEDIA_EXPORT MidiMessageQueue {
public:
// Initializes the queue. Set true to |allow_running_status| to enable
// "MIDI running status" reconstruction.
explicit MidiMessageQueue(bool allow_running_status);
~MidiMessageQueue();
// Enqueues |data| to the internal buffer.
void Add(const std::vector<uint8>& data);
void Add(const uint8* data, size_t length);
// Fills the next complete MIDI message into |message|. If |message| is
// not empty, the data sequence falls into one of the following types of
// MIDI message.
// - Single "Channel Voice Message" (w/o "System Real Time Messages")
// - Single "Channel Mode Message" (w/o "System Real Time Messages")
// - Single "System Exclusive Message" (w/o "System Real Time Messages")
// - Single "System Common Message" (w/o "System Real Time Messages")
// - Single "System Real Time message"
// |message| is empty if there is no complete MIDI message any more.
void Get(std::vector<uint8>* message);
private:
std::deque<uint8> queue_;
std::vector<uint8> next_message_;
const bool allow_running_status_;
DISALLOW_COPY_AND_ASSIGN(MidiMessageQueue);
};
} // namespace media
#endif // MEDIA_MIDI_MIDI_MESSAGE_QUEUE_H_