Start documenting BZip in code

SabreTools.Serialization/Models/BZip2/Archive.cs

@@ -1,10 +1,18 @@
 namespace SabreTools.Data.Models.BZip2
 {
-    /// <summary>
-    /// This is a placeholder model for future work
-    /// </summary>
+    /// <see href="https://github.com/dsnet/compress/blob/master/doc/bzip2-format.pdf"/>
     public class Archive
     {
+        /// <summary>
+        /// Stream header
+        /// </summary>
+        public Header? Header { get; set; }
 
+        // TODO: Implement remaining structures
+
+        /// <summary>
+        /// Stream footer
+        /// </summary>
+        public Footer? Footer { get; set; }
     }
 }

SabreTools.Serialization/Models/BZip2/Footer.cs

@@ -0,0 +1,27 @@
+namespace SabreTools.Data.Models.BZip2
+{
+    public class Footer
+    {
+        /// <summary>
+        /// A 48-bit integer value 17 72 45 38 50 90, which
+        /// is the binary-coded decimal representation of
+        /// sqrt(pi). It is used to differentiate the block
+        /// from the footer.
+        /// </summary>
+        /// <remarks>This may not be byte-aligned</remarks>
+        public byte[]? Magic { get; set; }
+
+        /// <summary>
+        /// Contains a custom checksum computed using each of
+        /// the Block CRCs.
+        /// </summary>
+        /// <remarks>This may not be byte-aligned</remarks>
+        public uint Checksum { get; set; }
+
+        /// <summary>
+        /// Used to align the bit-stream to the next byte-aligned
+        /// edge and will contain between 0 and 7 bits.
+        /// </summary>
+        public byte Padding { get; set; }
+    }
+}

SabreTools.Serialization/Models/BZip2/Header.cs

@@ -0,0 +1,25 @@
+namespace SabreTools.Data.Models.BZip2
+{
+    public class Header
+    {
+        /// <summary>
+        /// "BZ"
+        /// </summary>
+        public string? Signature { get; set; }
+
+        /// <summary>
+        /// Version byte
+        /// </summary>
+        /// <remarks>
+        /// '0' indicates a BZ1 file
+        /// 'h' indicates a BZ2 file
+        /// </remarks>
+        public byte Version { get; set; }
+
+        /// <summary>
+        /// ASCII value of the compression level
+        /// </summary>
+        /// <remarks>Valid values between '1' and '9'</remarks>
+        public byte Level { get; set; }
+    }
+}