| /* |
| * Copyright (C) 2014 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 an |
| * limitations under the License. |
| */ |
| |
| package com.android.server.midi; |
| |
| import android.midi.MidiDevice; |
| import android.midi.MidiDeviceInfo; |
| import android.midi.MidiUtils; |
| import android.os.Binder; |
| import android.util.Log; |
| |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.FileOutputStream; |
| import java.io.IOException; |
| |
| // This is our subclass of MidiDeviceBase for communicating with USB MIDI devices |
| // via the ALSA driver file system. |
| class UsbMidiDevice extends MidiDeviceBase { |
| private static final String TAG = "UsbMidiDevice"; |
| |
| private FileInputStream mInputStream; |
| private FileOutputStream mOutputStream; |
| private final byte[] mBuffer = new byte[3]; |
| |
| public UsbMidiDevice(MidiDeviceInfo info) { |
| super(info); |
| } |
| |
| public boolean open() { |
| if (mInputStream != null && mOutputStream != null) { |
| // already open |
| return true; |
| } |
| |
| int card = mDeviceInfo.getAlsaCard(); |
| int device = mDeviceInfo.getAlsaDevice(); |
| if (card == -1 || device == -1) { |
| Log.e(TAG, "Not a USB device!"); |
| return false; |
| } |
| |
| // clear calling identity so we can access the driver file. |
| long identity = Binder.clearCallingIdentity(); |
| |
| File file = new File("/dev/snd/midiC" + card + "D" + device); |
| try { |
| mInputStream = new FileInputStream(file); |
| mOutputStream = new FileOutputStream(file); |
| } catch (Exception e) { |
| Log.e(TAG, "could not open " + file); |
| return false; |
| } finally { |
| Binder.restoreCallingIdentity(identity); |
| } |
| |
| return true; |
| } |
| |
| void close() { |
| super.close(); |
| try { |
| if (mInputStream != null) { |
| mInputStream.close(); |
| } |
| if (mOutputStream != null) { |
| mOutputStream.close(); |
| } |
| } catch (IOException e) { |
| } |
| } |
| |
| // Reads a message from the ALSA driver. |
| // The driver may return multiple messages, so we have to read byte at a time. |
| int readMessage(byte[] buffer) throws IOException { |
| if (mInputStream.read(mBuffer, 0, 1) != 1) { |
| Log.e(TAG, "could not read command byte"); |
| return -1; |
| } |
| int dataSize = MidiUtils.getMessageDataSize(mBuffer[0]); |
| if (dataSize < 0) { |
| return -1; |
| } |
| if (dataSize > 0) { |
| if (mInputStream.read(mBuffer, 1, dataSize) != dataSize) { |
| Log.e(TAG, "could not read command data"); |
| return -1; |
| } |
| } |
| return MidiDevice.packMessage(mBuffer, 0, dataSize + 1, System.nanoTime(), |
| 0, // FIXME - multiple ports not supported yet |
| buffer); |
| } |
| |
| // writes a message to the ALSA driver |
| void writeMessage(byte[] buffer, int count) throws IOException { |
| int offset = MidiDevice.getMessageOffset(buffer, count); |
| int size = MidiDevice.getMessageSize(buffer, count); |
| // FIXME - multiple ports not supported yet |
| mOutputStream.write(buffer, offset, count); |
| } |
| } |
| |