[WebMIDI] Introduce UsbMidi{Input, Output}Stream.

media/midi/usb_midi_output_stream.h

+// Copyright 2014 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_USB_MIDI_OUTPUT_STREAM_H_
+#define MEDIA_MIDI_USB_MIDI_OUTPUT_STREAM_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "media/base/media_export.h"
+#include "media/midi/usb_midi_jack.h"
+
+namespace media {
+
+// UsbMidiOutputStream converts MIDI data to USB-MIDI data.
+// See "USB Device Class Definition for MIDI Devices" Release 1.0,
+// Section 4 "USB-MIDI Event Packets" for details.
+class MEDIA_EXPORT UsbMidiOutputStream {
+ public:
+  explicit UsbMidiOutputStream(const UsbMidiJack& jack);
+
+  // Converts |data| to USB-MIDI data and send it to the jack.
+  void Send(const std::vector<uint8>& data);
+
+ private:
+  size_t GetSize(const std::vector<uint8>& data) const;
+  uint8_t Get(const std::vector<uint8>& data, size_t index) const;
+
+  bool PushSysExMessage(const std::vector<uint8>& data,
+                        size_t* current,
+                        std::vector<uint8>* data_to_send);
+  bool PushSysCommonMessage(const std::vector<uint8>& data,
+                            size_t* current,
+                            std::vector<uint8>* data_to_send);
+  void PushSysRTMessage(const std::vector<uint8>& data,
+                        size_t* current,
+                        std::vector<uint8>* data_to_send);
+  bool PushChannelMessage(const std::vector<uint8>& data,
+                          size_t* current,
+                          std::vector<uint8>* data_to_send);
+
+  static const size_t kPacketContentSize = 3;
+
+  UsbMidiJack jack_;
+  size_t pending_size_;
+  uint8 pending_data_[kPacketContentSize];
+  bool is_sending_sysex_;
+
+  DISALLOW_COPY_AND_ASSIGN(UsbMidiOutputStream);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_MIDI_USB_MIDI_OUTPUT_STREAM_H_