C# Execute assembly sequence and other os function

using System;
using System.Reflection;

class Program
{
public delegate uint Ret1ArgDelegate(uint arg1);
static uint PlaceHolder1(uint arg1) { return 0; }

public static byte[] asmBytes = new byte[]
{
0x89,0xD0, // MOV EAX,EDX
0xD1,0xC8, // ROR EAX,1
0xC3       // RET
};

unsafe static void Main(string[] args)
{
fixed(byte* startAddress = &asmBytes[0]) // Take the address of our x86 code
{
// Get the FieldInfo for "_methodPtr"
Type delType = typeof(Delegate);
FieldInfo _methodPtr = delType.GetField("_methodPtr", BindingFlags.NonPublic | BindingFlags.Instance);

// Set our delegate to our x86 code
Ret1ArgDelegate del = new Ret1ArgDelegate(PlaceHolder1);
_methodPtr.SetValue(del, (IntPtr)startAddress);

// Enjoy
uint n = (uint)0xFFFFFFFC;
n = del(n);
Console.WriteLine("{0:x}", n);
}
}
}

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace DynamicX86
{
class Program
{
const uint PAGE_EXECUTE_READWRITE = 0x40;
const uint MEM_COMMIT = 0x1000;

[DllImport("kernel32.dll", SetLastError = true)]
static extern IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);

private delegate int IntReturner();

static void Main(string[] args)
{
List<byte> bodyBuilder = new List<byte>();
bodyBuilder.Add(0xb8);
bodyBuilder.AddRange(BitConverter.GetBytes(42));
bodyBuilder.Add(0xc3);
byte[] body = bodyBuilder.ToArray();
IntPtr buf = VirtualAlloc(IntPtr.Zero, (uint)body.Length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
Marshal.Copy(body, 0, buf, body.Length);

IntReturner ptr = (IntReturner)Marshal.GetDelegateForFunctionPointer(buf, typeof(IntReturner));
Console.WriteLine(ptr());
}
}
}