#1067 P25 Phase 1 C4FM/LSM decoder redesign. (#2294)

C4FM now uses SIMD differential decoding and soft sync detection.
LSM updated with soft sync detector and retains original Gardner error detector.
Adds new QPSK symbol view in the now playing channel tab.
Restores PLL error driven tuner Auto-PPM feature.
Deletes the demod viewer GUI application and all instrumented decoders
Updates DMR to send soft symbols to new symbol view in Now Playing.

Co-authored-by: Dennis Sheirer <dsheirer@github.com>

src/main/java/io/github/dsheirer/message/DroppedSamplesMessage.java

@@ -0,0 +1,106 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2025 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.message;
+
+import io.github.dsheirer.identifier.Identifier;
+import io.github.dsheirer.protocol.Protocol;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Empty message to convey that a number of dropped samples produced a shortfall of expected bits.  This can result
+ * from either the tuner dropping the samples, or from a decoder dropping samples due to timing adjustments.
+ *
+ * This message supports periodic updates to user to indicate that the USB bus and/or the tuner may be causing dropped
+ * samples.
+ */
+public class DroppedSamplesMessage extends Message
+{
+    private int mBitsDropped;
+    private Protocol mProtocol;
+    private int mTimeslot = 0;
+
+    /**
+     * Constructs a dropped samples message.
+     *
+     * @param timestamp of the message
+     * @param bitsDropped for the expected message length
+     * @param timeslot that lost the sync
+     */
+    public DroppedSamplesMessage(long timestamp, int bitsDropped, Protocol protocol, int timeslot)
+    {
+        super(timestamp);
+        mBitsDropped = bitsDropped;
+        mProtocol = protocol;
+        mTimeslot = timeslot;
+    }
+
+    /**
+     * Constructs a dropped samples message.
+     *
+     * @param timestamp of the message
+     * @param bitsDropped for the expected message length
+     */
+    public DroppedSamplesMessage(long timestamp, int bitsDropped, Protocol protocol)
+    {
+        this(timestamp, bitsDropped, protocol, 0);
+    }
+
+    /**
+     * Timeslot that has dropped bits
+     * @return timeslot or a default of 0
+     */
+    @Override
+    public int getTimeslot()
+    {
+        return mTimeslot;
+    }
+
+    /**
+     * Indicates the number of bits that were detected to be dropped
+     */
+    public int getBitsDropped()
+    {
+        return mBitsDropped;
+    }
+
+    @Override
+    public String toString()
+    {
+        return "<-> DROPPED SAMPLES (POSSIBLY) DETECTED -- COULD NOT ACCOUNT FOR [" + getBitsDropped() + "] SYMBOL BITS";
+    }
+
+    @Override
+    public boolean isValid()
+    {
+        return true;
+    }
+
+    @Override
+    public Protocol getProtocol()
+    {
+        return mProtocol;
+    }
+
+    @Override
+    public List<Identifier> getIdentifiers()
+    {
+        return Collections.EMPTY_LIST;
+    }
+}