content: /*
   * 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;
  
  /**
   * MIDI related constants and static methods.
   * These values are defined in the MIDI Standard 1.0
   * available from the MIDI Manufacturers Association.
   */
  public class MidiConstants {
      protected final static String TAG = "MidiTools";
      public static final byte STATUS_COMMAND_MASK = (byte) 0xF0;
      public static final byte STATUS_CHANNEL_MASK = (byte) 0x0F;
  
      // Channel voice messages.
      public static final byte STATUS_NOTE_OFF = (byte) 0x80;
      public static final byte STATUS_NOTE_ON = (byte) 0x90;
      public static final byte STATUS_POLYPHONIC_AFTERTOUCH = (byte) 0xA0;
      public static final byte STATUS_CONTROL_CHANGE = (byte) 0xB0;
      public static final byte STATUS_PROGRAM_CHANGE = (byte) 0xC0;
      public static final byte STATUS_CHANNEL_PRESSURE = (byte) 0xD0;
      public static final byte STATUS_PITCH_BEND = (byte) 0xE0;
  
      // System Common Messages.
      public static final byte STATUS_SYSTEM_EXCLUSIVE = (byte) 0xF0;
      public static final byte STATUS_MIDI_TIME_CODE = (byte) 0xF1;
      public static final byte STATUS_SONG_POSITION = (byte) 0xF2;
      public static final byte STATUS_SONG_SELECT = (byte) 0xF3;
      public static final byte STATUS_TUNE_REQUEST = (byte) 0xF6;
      public static final byte STATUS_END_SYSEX = (byte) 0xF7;
  
      // System Real-Time Messages
      public static final byte STATUS_TIMING_CLOCK = (byte) 0xF8;
      public static final byte STATUS_START = (byte) 0xFA;
      public static final byte STATUS_CONTINUE = (byte) 0xFB;
      public static final byte STATUS_STOP = (byte) 0xFC;
      public static final byte STATUS_ACTIVE_SENSING = (byte) 0xFE;
      public static final byte STATUS_RESET = (byte) 0xFF;
  
      /** Number of bytes in a message nc from 8c to Ec */
      public final static int CHANNEL_BYTE_LENGTHS[] = { 3, 3, 3, 3, 2, 2, 3 };
  
      /** Number of bytes in a message Fn from F0 to FF */
      public final static int SYSTEM_BYTE_LENGTHS[] = { 1, 2, 3, 2, 1, 1, 1, 1, 1,
              1, 1, 1, 1, 1, 1, 1 };
  
      /**
       * MIDI messages, except for SysEx, are 1,2 or 3 bytes long.
       * You can tell how long a MIDI message is from the first status byte.
       * Do not call this for SysEx, which has variable length.
       * @param statusByte
       * @return number of bytes in a complete message, zero if data byte passed
       */
      public static int getBytesPerMessage(byte statusByte) {
          // Java bytes are signed so we need to mask off the high bits
          // to get a value between 0 and 255.
          int statusInt = statusByte & 0xFF;
          if (statusInt >= 0xF0) {
              // System messages use low nibble for size.
              return SYSTEM_BYTE_LENGTHS[statusInt & 0x0F];
          } else if(statusInt >= 0x80) {
              // Channel voice messages use high nibble for size.
              return CHANNEL_BYTE_LENGTHS[(statusInt >> 4) - 8];
          } else {
              return 0; // data byte
          }
      }
  
      /**
       * @param msg
       * @param offset
       * @param count
       * @return true if the entire message is ActiveSensing commands
       */
      public static boolean isAllActiveSensing(byte[] msg, int offset,
              int count) {
          // Count bytes that are not active sensing.
          int goodBytes = 0;
          for (int i = 0; i < count; i++) {
              byte b = msg[offset + i];
              if (b != MidiConstants.STATUS_ACTIVE_SENSING) {
                  goodBytes++;
              }
          }
          return (goodBytes == 0);
      }
  
  }
  