61 Rotating Control Channel Support - P25 Decoder (#475)

* Initial work on add support for rotating control channels.

* Creates multiple frequency editor control.

* Updates channel source editor to allow user to select multi-frequency
configuration and add multiple frequencies.

* Adds full support for rotating control channels to the P25 channelizer.
Users define multiple frequencies in the channel source configuration.
The decoder monitors the state of the channel for a CONTROL state.  If
the state does not stay in the CONTROL state for a user-specified delay
value, then the decoder rotates to the next frequency in the list.  This
behavior continues until the decoder state once again changes to CONTROL.

This is NOT a 'scanner' feature.

src/main/java/io/github/dsheirer/preference/source/ChannelMultiFrequencyPreference.java

@@ -0,0 +1,96 @@
+/*
+ * ******************************************************************************
+ * sdrtrunk
+ * Copyright (C) 2014-2019 Dennis Sheirer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ * *****************************************************************************
+ */
+
+package io.github.dsheirer.preference.source;
+
+import io.github.dsheirer.preference.Preference;
+import io.github.dsheirer.preference.PreferenceType;
+import io.github.dsheirer.sample.Listener;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.prefs.Preferences;
+
+/**
+ * Preferences for multiple frequency tuner channel sources.
+ */
+public class ChannelMultiFrequencyPreference extends Preference
+{
+    private final static Logger mLog = LoggerFactory.getLogger(ChannelMultiFrequencyPreference.class);
+    private Preferences mPreferences = Preferences.userNodeForPackage(ChannelMultiFrequencyPreference.class);
+    private static final String PREFERENCE_KEY_ROTATION_DELAY = "rotation.delay";
+    private static final long DEFAULT_ROTATION_DELAY = 5000; //5 seconds
+    private Long mRotationDelay = DEFAULT_ROTATION_DELAY;
+
+    /**
+     * Constructs a tuner preference with the update listener
+     *
+     * @param updateListener
+     */
+    public ChannelMultiFrequencyPreference(Listener<PreferenceType> updateListener)
+    {
+        super(updateListener);
+    }
+
+    @Override
+    public PreferenceType getPreferenceType()
+    {
+        return PreferenceType.MULTI_FREQUENCY;
+    }
+
+    /**
+     * Rotation delay value in milliseconds.  This value is used for channel configurations where there source
+     * defines multiple frequencies for a system that employs rotating control channels.
+     */
+    public long getRotationDelay()
+    {
+        if(mRotationDelay == null)
+        {
+            mRotationDelay = mPreferences.getLong(PREFERENCE_KEY_ROTATION_DELAY, DEFAULT_ROTATION_DELAY);
+        }
+
+        return mRotationDelay;
+    }
+
+    /**
+     * Sets the rotation delay value in milliseconds.
+     * @param rotationDelay in milliseconds (1,000 - 60,000)
+     */
+    public void setRotationDelay(long rotationDelay)
+    {
+        if(1000 <= rotationDelay && rotationDelay <= 60000)
+        {
+            mRotationDelay = rotationDelay;
+            mPreferences.putLong(PREFERENCE_KEY_ROTATION_DELAY, mRotationDelay);
+            notifyPreferenceUpdated();
+        }
+    }
+
+    /**
+     * Resets the rotation delay and removes it from the preferences store, so that it can be recreated with
+     * a default value.
+     */
+    public void resetRotationDelay()
+    {
+        mPreferences.remove(PREFERENCE_KEY_ROTATION_DELAY);
+        mRotationDelay = null;
+        notifyPreferenceUpdated();
+    }
+}