130 lines
4.7 KiB
Java
130 lines
4.7 KiB
Java
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.internal.midi;
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import android.media.midi.MidiReceiver;
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//import android.util.Log;
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import java.io.IOException;
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/**
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* Convert stream of bytes to discrete messages.
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*
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* Parses the incoming bytes and then posts individual messages to the receiver
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* specified in the constructor. Short messages of 1-3 bytes will be complete.
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* System Exclusive messages may be posted in pieces.
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*
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* Resolves Running Status and
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* interleaved System Real-Time messages.
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*/
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public class MidiFramer extends MidiReceiver {
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public String TAG = "MidiFramer";
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private MidiReceiver mReceiver;
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private byte[] mBuffer = new byte[3];
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private int mCount;
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private byte mRunningStatus;
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private int mNeeded;
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private boolean mInSysEx;
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public MidiFramer(MidiReceiver receiver) {
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mReceiver = receiver;
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}
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public static String formatMidiData(byte[] data, int offset, int count) {
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String text = "MIDI+" + offset + " : ";
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for (int i = 0; i < count; i++) {
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text += String.format("0x%02X, ", data[offset + i]);
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}
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return text;
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}
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/*
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* @see android.midi.MidiReceiver#onSend(byte[], int, int, long)
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*/
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@Override
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public void onSend(byte[] data, int offset, int count, long timestamp)
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throws IOException {
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int sysExStartOffset = (mInSysEx ? offset : -1);
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for (int i = 0; i < count; i++) {
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final byte currentByte = data[offset];
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final int currentInt = currentByte & 0xFF;
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if (currentInt >= 0x80) { // status byte?
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if (currentInt < 0xF0) { // channel message?
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mRunningStatus = currentByte;
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mCount = 1;
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mNeeded = MidiConstants.getBytesPerMessage(currentByte) - 1;
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} else if (currentInt < 0xF8) { // system common?
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if (currentInt == 0xF0 /* SysEx Start */) {
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// Log.i(TAG, "SysEx Start");
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mInSysEx = true;
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sysExStartOffset = offset;
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} else if (currentInt == 0xF7 /* SysEx End */) {
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// Log.i(TAG, "SysEx End");
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if (mInSysEx) {
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mReceiver.send(data, sysExStartOffset,
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offset - sysExStartOffset + 1, timestamp);
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mInSysEx = false;
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sysExStartOffset = -1;
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}
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} else {
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mBuffer[0] = currentByte;
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mRunningStatus = 0;
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mCount = 1;
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mNeeded = MidiConstants.getBytesPerMessage(currentByte) - 1;
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}
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} else { // real-time?
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// Single byte message interleaved with other data.
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if (mInSysEx) {
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mReceiver.send(data, sysExStartOffset,
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offset - sysExStartOffset, timestamp);
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sysExStartOffset = offset + 1;
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}
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mReceiver.send(data, offset, 1, timestamp);
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}
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} else { // data byte
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if (!mInSysEx) {
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// Hack to avoid crashing if we start parsing in the middle
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// of a data stream
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if (mNeeded <= 0) {
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break;
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}
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mBuffer[mCount++] = currentByte;
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if (--mNeeded == 0) {
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if (mRunningStatus != 0) {
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mBuffer[0] = mRunningStatus;
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}
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mReceiver.send(mBuffer, 0, mCount, timestamp);
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mNeeded = MidiConstants.getBytesPerMessage(mBuffer[0]) - 1;
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mCount = 1;
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}
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}
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}
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++offset;
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}
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// send any accumulatedSysEx data
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if (sysExStartOffset >= 0 && sysExStartOffset < offset) {
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mReceiver.send(data, sysExStartOffset,
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offset - sysExStartOffset, timestamp);
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}
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}
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}
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