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copied!<p>The trick should be <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/aa366887%28v=vs.85%29.aspx">VirtualAlloc</a> with the <code>EXECUTE_READWRITE</code>-flag (needs P/Invoke) and <a href="http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.marshal.getdelegateforfunctionpointer.aspx">Marshal.GetDelegateForFunctionPointer</a>.</p> <p>Here is a modified version of the rotate integer example (note that no unsafe code is needed here):</p> <pre><code>[UnmanagedFunctionPointer(CallingConvention.Cdecl)] public delegate uint Ret1ArgDelegate(uint arg1); public static void Main(string[] args){ // Bitwise rotate input and return it. // The rest is just to handle CDECL calling convention. byte[] asmBytes = new byte[] { 0x55, // push ebp 0x8B, 0xEC, // mov ebp, esp 0x8B, 0x45, 0x08, // mov eax, [ebp+8] 0xD1, 0xC8, // ror eax, 1 0x5D, // pop ebp 0xC3 // ret }; // Allocate memory with EXECUTE_READWRITE permissions IntPtr executableMemory = VirtualAlloc( IntPtr.Zero, (UIntPtr) asmBytes.Length, AllocationType.COMMIT, MemoryProtection.EXECUTE_READWRITE ); // Copy the machine code into the allocated memory Marshal.Copy(asmBytes, 0, executableMemory, asmBytes.Length); // Create a delegate to the machine code. Ret1ArgDelegate del = (Ret1ArgDelegate) Marshal.GetDelegateForFunctionPointer( executableMemory, typeof(Ret1ArgDelegate) ); // Call it uint n = (uint)0xFFFFFFFC; n = del(n); Console.WriteLine("{0:x}", n); // Free the memory VirtualFree(executableMemory, UIntPtr.Zero, FreeType.DECOMMIT); } </code></pre> <p><a href="http://pastebin.com/rVbpLahs">Full example</a> (now works with both X86 and X64).</p>

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