1 files changed, 112 insertions, 0 deletions
diff --git a/common/src/java/com/example/android/common/midi/MidiFramer.java b/common/src/java/com/example/android/common/midi/MidiFramer.java
new file mode 100644
index 00000000..c274925a
--- /dev/null
+++ b/common/src/java/com/example/android/common/midi/MidiFramer.java
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+package com.example.android.common.midi;
+
+import android.media.midi.MidiReceiver;
+import android.util.Log;
+
+import java.io.IOException;
+
+/**
+ * Convert stream of arbitrary MIDI bytes into discrete messages.
+ *
+ * Parses the incoming bytes and then posts individual messages to the receiver
+ * specified in the constructor. Short messages of 1-3 bytes will be complete.
+ * System Exclusive messages may be posted in pieces.
+ *
+ * Resolves Running Status and interleaved System Real-Time messages.
+ */
+public class MidiFramer extends MidiReceiver {
+    private MidiReceiver mReceiver;
+    private byte[] mBuffer = new byte[3];
+    private int mCount;
+    private byte mRunningStatus;
+    private int mNeeded;
+    private boolean mInSysEx;
+
+    public MidiFramer(MidiReceiver receiver) {
+        mReceiver = receiver;
+    }
+
+    /*
+     * @see android.midi.MidiReceiver#onSend(byte[], int, int, long)
+     */
+    @Override
+    public void onSend(byte[] data, int offset, int count, long timestamp)
+            throws IOException {
+        int sysExStartOffset = (mInSysEx ? offset : -1);
+
+        for (int i = 0; i < count; i++) {
+            final byte currentByte = data[offset];
+            final int currentInt = currentByte & 0xFF;
+            if (currentInt >= 0x80) { // status byte?
+                if (currentInt < 0xF0) { // channel message?
+                    mRunningStatus = currentByte;
+                    mCount = 1;
+                    mNeeded = MidiConstants.getBytesPerMessage(currentByte) - 1;
+                } else if (currentInt < 0xF8) { // system common?
+                    if (currentInt == 0xF0 /* SysEx Start */) {
+                        // Log.i(TAG, "SysEx Start");
+                        mInSysEx = true;
+                        sysExStartOffset = offset;
+                    } else if (currentInt == 0xF7 /* SysEx End */) {
+                        // Log.i(TAG, "SysEx End");
+                        if (mInSysEx) {
+                            mReceiver.send(data, sysExStartOffset,
+                                offset - sysExStartOffset + 1, timestamp);
+                            mInSysEx = false;
+                            sysExStartOffset = -1;
+                        }
+                    } else {
+                        mBuffer[0] = currentByte;
+                        mRunningStatus = 0;
+                        mCount = 1;
+                        mNeeded = MidiConstants.getBytesPerMessage(currentByte) - 1;
+                    }
+                } else { // real-time?
+                    // Single byte message interleaved with other data.
+                    if (mInSysEx) {
+                        mReceiver.send(data, sysExStartOffset,
+                                offset - sysExStartOffset, timestamp);
+                        sysExStartOffset = offset + 1;
+                    }
+                    mReceiver.send(data, offset, 1, timestamp);
+                }
+            } else { // data byte
+                if (!mInSysEx) {
+                    mBuffer[mCount++] = currentByte;
+                    if (--mNeeded == 0) {
+                        if (mRunningStatus != 0) {
+                            mBuffer[0] = mRunningStatus;
+                        }
+                        mReceiver.send(mBuffer, 0, mCount, timestamp);
+                        mNeeded = MidiConstants.getBytesPerMessage(mBuffer[0]) - 1;
+                        mCount = 1;
+                    }
+                }
+            }
+            ++offset;
+        }
+
+        // send any accumulatedSysEx data
+        if (sysExStartOffset >= 0 && sysExStartOffset < offset) {
+            mReceiver.send(data, sysExStartOffset,
+                    offset - sysExStartOffset, timestamp);
+        }
+    }
+
+}