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

media/midi/usb_midi_input_stream.h

+// Copyright (c) 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_USB_MIDI_INPUT_STREAM_H_
+#define MEDIA_MIDI_USB_MIDI_INPUT_STREAM_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/containers/hash_tables.h"
+#include "media/base/media_export.h"
+#include "media/midi/usb_midi_jack.h"
+
+namespace media {
+
+class UsbMidiDevice;
+
+// UsbMidiInputStream converts USB-MIDI data to MIDI data.
+class MEDIA_EXPORT UsbMidiInputStream {
+ public:
+  class Delegate {
+   public:
+    virtual ~Delegate() {}
+    // This function is called when some data arrives to a USB-MIDI jack.
+    // An input USB-MIDI jack corresponds to an input MIDIPortInfo.
+    virtual void OnReceivedData(size_t jack_index,
+                                const uint8* data,
+                                size_t size,
+                                double timestamp) = 0;
+  };
+
+  UsbMidiInputStream(const std::vector<UsbMidiJack>& jacks,
+                     Delegate* delegate);
+  ~UsbMidiInputStream();
+  void OnReceivedData(UsbMidiDevice* device,
+                      int endpoint_number,
+                      const uint8* data,
+                      size_t size,
+                      double timestamp);
+  const std::vector<UsbMidiJack>& jacks() const { return jacks_; }
+
+ private:
+  static const size_t kPacketSize = 4;
+  struct JackUniqueKey {
+    JackUniqueKey(UsbMidiDevice* device, int endpoint_number, int cable_number);
+    bool operator==(const JackUniqueKey& key) const;
+
+    UsbMidiDevice* device;
+    int endpoint_number;
+    int cable_number;
+  };
+
+  struct JackHash {
+    size_t operator()(const JackUniqueKey& key) const;
+  };
+
+  void OnReceivedData(size_t jack_index,
+                      const uint8* data,
+                      size_t size,
+                      double timestamp);
+  // |packet[0:4]| must be accessible.
+  void ProcessOnePacket(UsbMidiDevice* device,
+                        int endpoint_number,
+                        const uint8* packet,
+                        double timestamp);
+
+  const std::vector<UsbMidiJack> jacks_;
+  // A map from UsbMidiJack to its index in |jacks_|.
+  base::hash_map<JackUniqueKey, size_t, JackHash> jack_dictionary_;
+
+  // Not owned
+  Delegate* delegate_;
+  uint8 pending_data_[kPacketSize];
+  size_t pending_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(UsbMidiInputStream);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_MIDI_USB_MIDI_INPUT_STREAM_H_