#7 NXDN Decoder support. Redesigns tuner and channel frequency error management. (#2431)

Closes #7 

NXDN Decoder

* Implements: NXDN4800, NXDN9600, Type-C and Type-D decoding and trunk tracking.
* Redesigns tuner and channel frequency error management.

src/main/java/io/github/dsheirer/bits/BinaryMessage.java

@@ -1,6 +1,6 @@
 /*
  * *****************************************************************************
- * Copyright (C) 2014-2025 Dennis Sheirer
+ * Copyright (C) 2014-2026 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
@@ -306,6 +306,15 @@ public class BinaryMessage extends BitSet
     }
 
     public String toString()
+    {
+        return toHexString();
+    }
+
+    /**
+     * Binary representation of the message
+     * @return message in binary 0/1 format
+     */
+    public String toBinaryString()
     {
         StringBuilder sb = new StringBuilder();
 
@@ -317,6 +326,10 @@ public class BinaryMessage extends BitSet
         return sb.toString();
     }
 
+    /**
+     * Hex string representation of the message
+     * @return message in hex
+     */
     public String toHexString()
     {
         StringBuilder sb = new StringBuilder();
@@ -997,6 +1010,18 @@ public class BinaryMessage extends BitSet
         return String.format("%0" + width + "X", getInt(field));
     }
 
+    /**
+     * Returns the long field formatted as a hex value using zero prefixes to pad the hex character count to fully
+     * represent the size (width) of the field.
+     * @param field to parse as hex
+     * @return hex value.
+     */
+    public String getHex(LongField field)
+    {
+        int width = Math.ceilDiv(field.width(), 4);
+        return String.format("%0" + width + "X", getLong(field));
+    }
+
     /**
      * Format the byte value that starts at the specified index as hexadecimal.  If the length of the message is less
      * than the start index plus 7 bits, then the value represents those bits as high-order bits with zero padding in
@@ -1315,37 +1340,15 @@ public class BinaryMessage extends BitSet
             throw new IllegalArgumentException("Message must contain only 0-9 and A-F hexadecimal characters");
         }
 
-        int length = hex.length() / 2;
+        BinaryMessage message = new BinaryMessage(hex.length() * 4);
 
-        if(length * 2 < hex.length())
+        for(int x = 0; x < hex.length(); x++)
         {
-            length++;
+            String rawHex = hex.substring(x, x + 1);
+            message.setInt(Integer.parseInt(rawHex, 16), IntField.length4(x * 4));
         }
 
-        BinaryMessage buffer = new BinaryMessage(length * 8);
-
-        int bufferOffset = 0;
-        for(int x = 0; x < hex.length(); x += 2)
-        {
-            int endIndex = x + 2;
-            if(endIndex > hex.length())
-            {
-                endIndex--;
-            }
-
-            String rawHex = hex.substring(x, endIndex);
-
-            if(rawHex.length() == 1)
-            {
-                rawHex = rawHex + "0";
-            }
-
-            int value = Integer.parseInt(rawHex, 16);
-            buffer.setByte(bufferOffset, (byte)(value & 0xFF));
-            bufferOffset += 8;
-        }
-
-        return buffer;
+        return message;
     }
 
     /**

src/main/java/io/github/dsheirer/bits/CorrectedBinaryMessage.java

@@ -1,6 +1,6 @@
 /*
  * *****************************************************************************
- * Copyright (C) 2014-2024 Dennis Sheirer
+ * Copyright (C) 2014-2026 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
@@ -18,6 +18,7 @@
  */
 package io.github.dsheirer.bits;
 
+import java.nio.ByteOrder;
 import java.util.BitSet;
 
 public class CorrectedBinaryMessage extends BinaryMessage
@@ -54,6 +55,45 @@ public class CorrectedBinaryMessage extends BinaryMessage
         this.xor(message);
     }
 
+    /**
+     * Creates a new message loaded from the hexadecimal string
+     * @param hex representing the bits of the message
+     * @return new message
+     */
+    public static CorrectedBinaryMessage loadHex(String hex)
+    {
+        return new CorrectedBinaryMessage(BinaryMessage.loadHex(hex));
+    }
+
+    /**
+     * Overloads the parent method to return this type.
+     * @param binary message to load
+     * @return loaded message
+     */
+    public static CorrectedBinaryMessage load(String binary)
+    {
+        return new CorrectedBinaryMessage(BinaryMessage.load(binary));
+    }
+
+    /**
+     * Constructs a binary frame from the byte array with length set to the
+     * number of bits contained in the byte array
+     */
+    public static CorrectedBinaryMessage from(byte[] data, ByteOrder byteOrder)
+    {
+        if(byteOrder == ByteOrder.LITTLE_ENDIAN)
+        {
+            return new CorrectedBinaryMessage(from(data));
+        }
+        else
+        {
+            CorrectedBinaryMessage frame = new CorrectedBinaryMessage(data.length * 8);
+            BitSet bitSet = BitSet.valueOf(data);
+            frame.xor(bitSet);
+            return frame;
+        }
+    }
+
     @Override
     public int getCorrectedBitCount()
     {

src/main/java/io/github/dsheirer/bits/IntField.java

@@ -1,6 +1,6 @@
 /*
  * *****************************************************************************
- * Copyright (C) 2014-2025 Dennis Sheirer
+ * Copyright (C) 2014-2026 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
@@ -60,7 +60,27 @@ public record IntField(int start, int end)
     }
 
     /**
-     * Utility constructor method for a field with one four bits of length.
+     * Utility constructor method for a field with two bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length2(int start)
+    {
+        return new IntField(start, (start + 1));
+    }
+
+    /**
+     * Utility constructor method for a field with three bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length3(int start)
+    {
+        return new IntField(start, (start + 2));
+    }
+
+    /**
+     * Utility constructor method for a field with four bits of length.
      * @param start index (inclusive)
      * @return constructed bit field.
      */
@@ -70,7 +90,17 @@ public record IntField(int start, int end)
     }
 
     /**
-     * Utility constructor method for a field with one four bits of length.
+     * Utility constructor method for a field with five bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length5(int start)
+    {
+        return new IntField(start, (start + 4));
+    }
+
+    /**
+     * Utility constructor method for a field with six bits of length.
      * @param start index (inclusive)
      * @return constructed bit field.
      */
@@ -79,6 +109,16 @@ public record IntField(int start, int end)
         return new IntField(start, (start + 5));
     }
 
+    /**
+     * Utility constructor method for a field with seven bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length7(int start)
+    {
+        return new IntField(start, (start + 6));
+    }
+
     /**
      * Utility constructor method for a field with one octet of length.
      * @param start index (inclusive)
@@ -89,6 +129,36 @@ public record IntField(int start, int end)
         return new IntField(start, (start + 7));
     }
 
+    /**
+     * Utility constructor method for a field with nine bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length9(int start)
+    {
+        return new IntField(start, (start + 8));
+    }
+
+    /**
+     * Utility constructor method for a field with ten bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length10(int start)
+    {
+        return new IntField(start, (start + 9));
+    }
+
+    /**
+     * Utility constructor method for a field with eleven bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length11(int start)
+    {
+        return new IntField(start, (start + 10));
+    }
+
     /**
      * Utility constructor method for a field with 12 bits of length.
      * @param start index (inclusive)
@@ -99,6 +169,26 @@ public record IntField(int start, int end)
         return new IntField(start, (start + 11));
     }
 
+    /**
+     * Utility constructor method for a field with 14 bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length14(int start)
+    {
+        return new IntField(start, (start + 13));
+    }
+
+    /**
+     * Utility constructor method for a field with 15 bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static IntField length15(int start)
+    {
+        return new IntField(start, (start + 14));
+    }
+
     /**
      * Utility constructor method for a field with two octets of length.
      * @param start index (inclusive)

src/main/java/io/github/dsheirer/bits/LongField.java

@@ -1,6 +1,6 @@
 /*
  * *****************************************************************************
- * Copyright (C) 2014-2024 Dennis Sheirer
+ * Copyright (C) 2014-2026 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
@@ -39,6 +39,15 @@ public record LongField(int start, int end)
         }
     }
 
+    /**
+     * Width of the field in bit positions
+     * @return width
+     */
+    public int width()
+    {
+        return end() - start() + 1;
+    }
+
     /**
      * Utility constructor method.
      * @param start index (inclusive)
@@ -101,7 +110,17 @@ public record LongField(int start, int end)
     }
 
     /**
-     * Utility constructor method for a field with two octets of length.
+     * Utility constructor method for a field with 23 bits of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static LongField length23(int start)
+    {
+        return new LongField(start, (start + 22));
+    }
+
+    /**
+     * Utility constructor method for a field with three octets of length.
      * @param start index (inclusive)
      * @return constructed bit field.
      */
@@ -111,7 +130,7 @@ public record LongField(int start, int end)
     }
 
     /**
-     * Utility constructor method for a field with three octets of length.
+     * Utility constructor method for a field with four octets of length.
      * @param start index (inclusive)
      * @return constructed bit field.
      */
@@ -119,4 +138,24 @@ public record LongField(int start, int end)
     {
         return new LongField(start, (start + 31));
     }
+
+    /**
+     * Utility constructor method for a field with seven octets of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static LongField length56(int start)
+    {
+        return new LongField(start, (start + 55));
+    }
+
+    /**
+     * Utility constructor method for a field with eight octets of length.
+     * @param start index (inclusive)
+     * @return constructed bit field.
+     */
+    public static LongField length64(int start)
+    {
+        return new LongField(start, (start + 63));
+    }
 }