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diff --git a/ios/WALT/MIDIMessage.h b/ios/WALT/MIDIMessage.h
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+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#import <Foundation/Foundation.h>
+
+/**
+ * A MIDI channel number.
+ *
+ * Note that the first channel is '1'.
+ */
+typedef uint8_t MIDIChannel;
+typedef uint8_t MIDIByte;
+
+typedef NS_ENUM(MIDIByte, MIDIMessageType) {
+  // Channel messages
+  MIDIMessageNoteOff          = 0x08,
+  MIDIMessageNoteOn           = 0x09,
+  MIDIMessageKeyPressure      = 0x0A,
+  MIDIMessageControlChange    = 0x0B,
+  MIDIMessageProgramChange    = 0x0C,
+  MIDIMessageChannelPressure  = 0x0D,
+  MIDIMessagePitchBend        = 0x0E,
+  
+  // System messages
+  MIDIMessageSysEx            = 0xF0,
+  MIDIMessageQuarterFrame     = 0xF1,
+  MIDIMessageSongPosition     = 0xF2,
+  MIDIMessageSongSelect       = 0xF3,
+  MIDIMessageTuneRequest      = 0xF6,
+  MIDIMessageSysExEnd         = 0xF7,
+  MIDIMessageTimingClock      = 0xF8,
+  MIDIMessageStart            = 0xFA,
+  MIDIMessageContinue         = 0xFB,
+  MIDIMessageStop             = 0xFC,
+  MIDIMessageActiveSensing    = 0xFE,
+  MIDIMessageReset            = 0xFF,
+};
+
+extern const MIDIChannel kMIDINoChannel;
+
+#pragma mark Message Parsing
+
+/** Returns the MIDIMessageType for a given status byte. */
+MIDIMessageType MIDIMessageTypeFromStatus(MIDIByte status);
+
+/**
+ * Returns the MIDIChannel for a given status byte, or kMIDINoChannel if the status byte does not
+ * describe a channel message.
+ */
+MIDIChannel MIDIChannelFromStatus(MIDIByte status);
+
+/**
+ * Returns the body portion from a complete MIDI message (i.e., without leading or trailing data).
+ */
+NSData *MIDIMessageBody(NSData *message);
+
+#pragma mark Message Building
+
+/** Returns the MIDI status byte for a message type sent to a particular channel. */
+MIDIByte MIDIStatusByte(MIDIMessageType type, MIDIChannel channel);
+
+/** Creates a complete MIDI message packet for a given message type, channel, and its body. */
+NSData *MIDIMessageCreate(MIDIMessageType type, MIDIChannel channel, NSData *body);
+
+/** Creates a complete MIDI message packet for a simple message containing one data byte. */
+NSData *MIDIMessageCreateSimple1(MIDIMessageType type, MIDIChannel channel, MIDIByte first);
+
+/** Creates a complete MIDI message packet for a simple message containing two data bytes. */
+NSData *MIDIMessageCreateSimple2(MIDIMessageType type,
+                                 MIDIChannel channel,
+                                 MIDIByte first,
+                                 MIDIByte second);