Switch MappedMappedDataSource to UnmanagedDataSource

src/AsmResolver/IO/MemoryMappedInputFile.cs

@@ -10,17 +10,17 @@ namespace AsmResolver.IO
     public sealed class MemoryMappedInputFile : IInputFile
     {
         private readonly MemoryMappedFileShim _file;
-        private readonly MemoryMappedDataSource _dataSource;
+        private readonly UnmanagedDataSource _dataSource;
 
         /// <summary>
         /// Creates a new reader factory for the provided file.
         /// </summary>
         /// <param name="filePath">The path to the file to read.</param>
-        public MemoryMappedInputFile(string filePath)
+        public unsafe MemoryMappedInputFile(string filePath)
         {
             FilePath = filePath ?? throw new ArgumentNullException(nameof(filePath));
             _file = new MemoryMappedFileShim(filePath);
-            _dataSource = new MemoryMappedDataSource(_file);
+            _dataSource = new UnmanagedDataSource(_file.BasePointer, (ulong)_file.Size);
         }
 
         /// <inheritdoc />
@@ -33,14 +33,13 @@ public string FilePath
         public uint Length => (uint) _dataSource.Length;
 
         /// <inheritdoc />
-        public BinaryStreamReader CreateReader(ulong address, uint rva, uint length) =>
-            new(_dataSource, address, rva, length);
+        public unsafe BinaryStreamReader CreateReader(ulong address, uint rva, uint length) =>
+            new(_dataSource, address != 0 ? address : (ulong)_file.BasePointer, rva, length);
 
         /// <inheritdoc />
         public void Dispose()
         {
             _file.Dispose();
-            _dataSource.Dispose();
         }
     }
 }

src/AsmResolver/Shims/MemoryMappedFileShim.cs

@@ -17,6 +17,7 @@ public MemoryMappedFileShim(string path)
     }
 
     public long Size => _size;
+    public byte* BasePointer => _file;
 
     public byte ReadByte(long address)
     {
@@ -27,16 +28,6 @@ public byte ReadByte(long address)
         return _file[address];
     }
 
-    public ReadOnlySpan<byte> GetSpan(long offset, int length)
-    {
-        if (_file == null)
-            throw new ObjectDisposedException("disposed");
-        long newSize = _size - offset;
-        if (offset < 0 || newSize < 0 || length > newSize)
-            throw new ArgumentOutOfRangeException();
-        return new(_file + offset, length);
-    }
-
     private void DisposeCore()
     {
         void* filePointer;

test/AsmResolver.Tests/IO/MemoryMappedIOTest.cs

@@ -1,3 +1,4 @@
+using System;
 using System.IO;
 using AsmResolver.IO;
 using AsmResolver.Tests.Runners;