1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.example.android.common.midi; 18 19 /** 20 * MIDI related constants and static methods. 21 * These values are defined in the MIDI Standard 1.0 22 * available from the MIDI Manufacturers Association. 23 */ 24 public class MidiConstants { 25 protected final static String TAG = "MidiTools"; 26 public static final byte STATUS_COMMAND_MASK = (byte) 0xF0; 27 public static final byte STATUS_CHANNEL_MASK = (byte) 0x0F; 28 29 // Channel voice messages. 30 public static final byte STATUS_NOTE_OFF = (byte) 0x80; 31 public static final byte STATUS_NOTE_ON = (byte) 0x90; 32 public static final byte STATUS_POLYPHONIC_AFTERTOUCH = (byte) 0xA0; 33 public static final byte STATUS_CONTROL_CHANGE = (byte) 0xB0; 34 public static final byte STATUS_PROGRAM_CHANGE = (byte) 0xC0; 35 public static final byte STATUS_CHANNEL_PRESSURE = (byte) 0xD0; 36 public static final byte STATUS_PITCH_BEND = (byte) 0xE0; 37 38 // System Common Messages. 39 public static final byte STATUS_SYSTEM_EXCLUSIVE = (byte) 0xF0; 40 public static final byte STATUS_MIDI_TIME_CODE = (byte) 0xF1; 41 public static final byte STATUS_SONG_POSITION = (byte) 0xF2; 42 public static final byte STATUS_SONG_SELECT = (byte) 0xF3; 43 public static final byte STATUS_TUNE_REQUEST = (byte) 0xF6; 44 public static final byte STATUS_END_SYSEX = (byte) 0xF7; 45 46 // System Real-Time Messages 47 public static final byte STATUS_TIMING_CLOCK = (byte) 0xF8; 48 public static final byte STATUS_START = (byte) 0xFA; 49 public static final byte STATUS_CONTINUE = (byte) 0xFB; 50 public static final byte STATUS_STOP = (byte) 0xFC; 51 public static final byte STATUS_ACTIVE_SENSING = (byte) 0xFE; 52 public static final byte STATUS_RESET = (byte) 0xFF; 53 54 /** Number of bytes in a message nc from 8c to Ec */ 55 public final static int CHANNEL_BYTE_LENGTHS[] = { 3, 3, 3, 3, 2, 2, 3 }; 56 57 /** Number of bytes in a message Fn from F0 to FF */ 58 public final static int SYSTEM_BYTE_LENGTHS[] = { 1, 2, 3, 2, 1, 1, 1, 1, 1, 59 1, 1, 1, 1, 1, 1, 1 }; 60 61 /** 62 * MIDI messages, except for SysEx, are 1,2 or 3 bytes long. 63 * You can tell how long a MIDI message is from the first status byte. 64 * Do not call this for SysEx, which has variable length. 65 * @param statusByte 66 * @return number of bytes in a complete message, zero if data byte passed 67 */ 68 public static int getBytesPerMessage(byte statusByte) { 69 // Java bytes are signed so we need to mask off the high bits 70 // to get a value between 0 and 255. 71 int statusInt = statusByte & 0xFF; 72 if (statusInt >= 0xF0) { 73 // System messages use low nibble for size. 74 return SYSTEM_BYTE_LENGTHS[statusInt & 0x0F]; 75 } else if(statusInt >= 0x80) { 76 // Channel voice messages use high nibble for size. 77 return CHANNEL_BYTE_LENGTHS[(statusInt >> 4) - 8]; 78 } else { 79 return 0; // data byte 80 } 81 } 82 83 /** 84 * @param msg 85 * @param offset 86 * @param count 87 * @return true if the entire message is ActiveSensing commands 88 */ 89 public static boolean isAllActiveSensing(byte[] msg, int offset, 90 int count) { 91 // Count bytes that are not active sensing. 92 int goodBytes = 0; 93 for (int i = 0; i < count; i++) { 94 byte b = msg[offset + i]; 95 if (b != MidiConstants.STATUS_ACTIVE_SENSING) { 96 goodBytes++; 97 } 98 } 99 return (goodBytes == 0); 100 } 101 102 } 103
