Аналог memset или FillChar в С#

byte[] buffer = new byte[32];

public static void MemSet(byte[] array, byte value) {
  if (array == null) {
    throw new ArgumentNullException("array");
  }
  const int blockSize = 4096; // bigger may be better to a certain extent
  int index = 0;
  int length = Math.Min(blockSize, array.Length);
  while (index < length) {
    array[index++] = value;
  }
  length = array.Length;
  while (index < length) {
    Buffer.BlockCopy(array, 0, array, index, Math.Min(blockSize, length-index));
    index += blockSize;
  }
}

using System;
using System.Runtime.InteropServices;
 
class Program
{
    [DllImport("MSVCRT.DLL", CallingConvention = CallingConvention.Cdecl)]
    static extern IntPtr memset(IntPtr dest, int c, uint size);
 
    unsafe static void Main(string[] args)
    {
        byte[] b = new byte[4] {
                1, 2, 3, 4
            };
        Console.WriteLine(string.Join(" ", b));
        fixed (byte* ptr = b)
        {
            IntPtr p = (IntPtr)ptr;
            memset(p, 0, (uint)b.Length);
        }
        Console.WriteLine(string.Join(" ", b));
    }
}