001package com.pi4j.jni;
002
003/*
004 * #%L
005 * **********************************************************************
006 * ORGANIZATION  :  Pi4J
007 * PROJECT       :  Pi4J :: Java Library (Core)
008 * FILENAME      :  SerialInterrupt.java
009 *
010 * This file is part of the Pi4J project. More information about
011 * this project can be found here:  https://www.pi4j.com/
012 * **********************************************************************
013 * %%
014 * Copyright (C) 2012 - 2021 Pi4J
015 * %%
016 * This program is free software: you can redistribute it and/or modify
017 * it under the terms of the GNU Lesser General Public License as
018 * published by the Free Software Foundation, either version 3 of the
019 * License, or (at your option) any later version.
020 *
021 * This program is distributed in the hope that it will be useful,
022 * but WITHOUT ANY WARRANTY; without even the implied warranty of
023 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
024 * GNU General Lesser Public License for more details.
025 *
026 * You should have received a copy of the GNU General Lesser Public
027 * License along with this program.  If not, see
028 * <http://www.gnu.org/licenses/lgpl-3.0.html>.
029 * #L%
030 */
031
032
033import com.pi4j.util.NativeLibraryLoader;
034
035import java.util.Map;
036import java.util.concurrent.ConcurrentHashMap;
037
038/**
039 * <p>
040 * This class provides static methods to configure the native Pi4J library to listen to serial
041 * interrupts and invoke callbacks into this class. Additionally, this class provides a listener
042 * registration allowing Java consumers to subscribe to serial data receive events.
043 * </p>
044 *
045 * @see <a href="https://www.pi4j.com/">https://www.pi4j.com/</a>
046 * @author Robert Savage (<a
047 *         href="http://www.savagehomeautomation.com">http://www.savagehomeautomation.com</a>)
048 */
049public class SerialInterrupt {
050
051    private static Map<Integer, SerialInterruptListener> listeners = new ConcurrentHashMap<>();
052
053    // private constructor
054    private SerialInterrupt()  {
055        // forbid object construction
056    }
057
058    static {
059        // Load the platform library
060        NativeLibraryLoader.load("libpi4j.so", "pi4j");
061    }
062
063    /**
064     * <p>
065     * This method is used to instruct the native code to setup a monitoring thread to monitor
066     * interrupts that represent changes to the selected serial port.
067     * </p>
068     *
069     * @param fileDescriptor the serial file descriptor/handle
070     * @return A return value of a negative number represents an error. A return value of '0'
071     *         represents success and that the serial port is already being monitored. A return value
072     *         of '1' represents success and that a new monitoring thread was created to handle the
073     *         requested serial port.
074     */
075    public static native int enableSerialDataReceiveCallback(int fileDescriptor);
076
077    /**
078     * <p>
079     * This method is used to instruct the native code to stop the monitoring thread monitoring
080     * interrupts on the selected serial port.
081     * </p>
082     *
083     * @param fileDescriptor the serial file descriptor/handle
084
085     * @return A return value of a negative number represents an error. A return value of '0'
086     *         represents success and that no existing monitor was previously running. A return
087     *         value of '1' represents success and that an existing monitoring thread was stopped
088     *         for the requested serial port.
089     */
090    public static native int disableSerialDataReceiveCallback(int fileDescriptor);
091
092    /**
093     * <p>
094     * This method is provided as the callback handler for the Pi4J native library to invoke when a
095     * GPIO interrupt is detected. This method should not be called from any Java consumers. (Thus
096     * is is marked as a private method.)
097     * </p>
098     *
099     * @param fileDescriptor the serial file descriptor/handle
100     * //@param data byte array of data received on this event from the serial receive buffer
101     */
102    private static void onDataReceiveCallback(int fileDescriptor, byte[] data) {
103
104        // notify event listeners
105        if(listeners.containsKey(fileDescriptor)){
106            SerialInterruptListener listener = listeners.get(fileDescriptor);
107            if(listener != null) {
108                SerialInterruptEvent event = new SerialInterruptEvent(listener, fileDescriptor, data);
109                listener.onDataReceive(event);
110            }
111        }
112
113        //System.out.println("SERIAL PORT [" + fileDescriptor + "] DATA LENGTH = " + data.length + " / " + new String(data));
114    }
115
116    /**
117     * <p>
118     * Java consumer code can all this method to register itself as a listener for pin state
119     * changes.
120     * </p>
121     *
122     * @see com.pi4j.jni.SerialInterruptListener
123     * @see com.pi4j.jni.SerialInterruptEvent
124     *
125     * @param fileDescriptor the serial file descriptor/handle
126     * @param listener A class instance that implements the GpioInterruptListener interface.
127     */
128    public static synchronized void addListener(int fileDescriptor, SerialInterruptListener listener) {
129        if (!listeners.containsKey(fileDescriptor)) {
130            listeners.put(fileDescriptor, listener);
131            enableSerialDataReceiveCallback(fileDescriptor);
132        }
133    }
134
135    /**
136     * <p>
137     * Java consumer code can all this method to unregister itself as a listener for pin state
138     * changes.
139     * </p>
140     *
141     * @see com.pi4j.jni.SerialInterruptListener
142     * @see com.pi4j.jni.SerialInterruptEvent
143     *
144     * @param fileDescriptor the serial file descriptor/handle
145     */
146    public static synchronized void removeListener(int fileDescriptor) {
147        if (listeners.containsKey(fileDescriptor)) {
148            listeners.remove(fileDescriptor);
149            disableSerialDataReceiveCallback(fileDescriptor);
150        }
151    }
152
153
154    /**
155     * <p>
156     * Returns true if the listener is already registered for event callbacks.
157     * </p>
158     *
159     * @see com.pi4j.jni.SerialInterruptListener
160     * @see com.pi4j.jni.SerialInterruptEvent
161     *
162     * @param fileDescriptor the serial file descriptor/handle
163     */
164    public static synchronized boolean hasListener(int fileDescriptor) {
165        return listeners.containsKey(fileDescriptor);
166    }
167}