| /* |
| * 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.android.internal.midi; |
| |
| /** |
| * MIDI related constants and static methods. |
| */ |
| public final class MidiConstants { |
| 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 or 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); |
| } |
| |
| // Returns true if this command can be used for running status |
| public static boolean allowRunningStatus(byte command) { |
| // only Channel Voice and Channel Mode commands can use running status |
| return (command >= STATUS_NOTE_OFF && command < STATUS_SYSTEM_EXCLUSIVE); |
| } |
| |
| // Returns true if this command cancels running status |
| public static boolean cancelsRunningStatus(byte command) { |
| // System Common messages cancel running status |
| return (command >= STATUS_SYSTEM_EXCLUSIVE && command <= STATUS_END_SYSEX); |
| } |
| } |