imporved the decoding of numeric fields

Author: kerryjiang

src/SciSharp.MySQL.Replication/SequenceReaderExtensions.cs

@@ -133,7 +133,7 @@ internal static string ReadString(ref this SequenceReader<byte> reader, Encoding
         }
 
         /// <summary>
-        /// Reads a fixed-length integer from the binary stream.
+        /// Reads a fixed-length unsigned integer from the binary stream.
         /// </summary>
         /// <param name="reader">The sequence reader.</param>
         /// <param name="length">The number of bytes to read (1-4).</param>

src/SciSharp.MySQL.Replication/Types/Int24Type.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Buffers;
+using System.Buffers.Binary;
 
 namespace SciSharp.MySQL.Replication.Types
 {
@@ -19,7 +20,27 @@ class Int24Type : IMySQLDataType
         /// <returns>An integer representing the MySQL MEDIUMINT value.</returns>
         public object ReadValue(ref SequenceReader<byte> reader, ColumnMetadata columnMetadata)
         {
-            return reader.ReadInteger(3);
+            Span<byte> buffer = stackalloc byte[4];
+
+            reader.TryCopyTo(buffer.Slice(0, 3));
+            reader.Advance(3);
+            
+            buffer[3] = 0;
+
+            var signalByte = buffer[2];
+
+            if (!columnMetadata.IsUnsigned && (signalByte & 0x80) == 0x80) // Negative value
+            {
+                buffer[3] = 0xFF; // Set the sign bit for negative values
+            }
+            else
+            {
+                buffer[3] = 0x00; // Set the sign bit for positive values
+            }
+
+            return columnMetadata.IsUnsigned
+                ? BinaryPrimitives.ReadUInt32LittleEndian(buffer)
+                : BinaryPrimitives.ReadInt32LittleEndian(buffer);
         }
     }
 }

src/SciSharp.MySQL.Replication/Types/LongType.cs

@@ -2,6 +2,7 @@
 using System.Threading.Tasks;
 using System.Collections.Generic;
 using System.Buffers;
+using System.Buffers.Binary;
 
 namespace SciSharp.MySQL.Replication.Types
 {
@@ -21,7 +22,14 @@ class LongType : IMySQLDataType
         /// <returns>An integer representing the MySQL INT value.</returns>
         public object ReadValue(ref SequenceReader<byte> reader, ColumnMetadata columnMetadata)
         {
-            return reader.ReadInteger(4);
+            Span<byte> buffer = stackalloc byte[sizeof(int)];
+
+            reader.TryCopyTo(buffer);
+            reader.Advance(sizeof(int));
+
+            return columnMetadata.IsUnsigned
+                ? BinaryPrimitives.ReadUInt32LittleEndian(buffer)
+                : BinaryPrimitives.ReadInt32LittleEndian(buffer);
         }
     }
 }

src/SciSharp.MySQL.Replication/Types/ShortType.cs

@@ -2,6 +2,7 @@
 using System.Threading.Tasks;
 using System.Collections.Generic;
 using System.Buffers;
+using System.Buffers.Binary;
 
 namespace SciSharp.MySQL.Replication.Types
 {
@@ -21,7 +22,14 @@ class ShortType : IMySQLDataType
         /// <returns>A short value representing the MySQL SMALLINT value.</returns>
         public object ReadValue(ref SequenceReader<byte> reader, ColumnMetadata columnMetadata)
         {
-            return (short)reader.ReadInteger(2);
+            Span<byte> buffer = stackalloc byte[sizeof(short)];
+
+            reader.TryCopyTo(buffer);
+            reader.Advance(sizeof(short));
+
+            return columnMetadata.IsUnsigned
+                ? (ushort)BinaryPrimitives.ReadUInt16LittleEndian(buffer)
+                : (short)BinaryPrimitives.ReadInt16LittleEndian(buffer);
         }
     }
 }

src/SciSharp.MySQL.Replication/Types/TinyType.cs

@@ -20,7 +20,9 @@ class TinyType : IMySQLDataType
         public object ReadValue(ref SequenceReader<byte> reader, ColumnMetadata columnMetadata)
         {
             reader.TryRead(out byte x);
-            return (SByte)x;
+            return columnMetadata.IsUnsigned
+                ? x
+                : (sbyte)x;
         }
     }
 }