quickly read bytes from a memory mapped file

MemoryMapppedIOExtensions.cs

// Copied from
// http://stackoverflow.com/questions/7956167/how-can-i-quickly-read-bytes-from-a-memory-mapped-file-in-net

public static MemoryMapppedIOExtensions
{
    public unsafe byte[] ReadBytesFast(this MemoryMappedViewAccessor view, int offset, int num)
    {
        try 
        {
            byte[] arr = new byte[num];
            byte *ptr = (byte*)0;
            _view.SafeMemoryMappedViewHandle.AcquirePointer(ref ptr);
            Marshal.Copy(IntPtr.Add(new IntPtr(ptr), offset), arr, 0, num);
        }
        finally
        {
            _view.SafeMemoryMappedViewHandle.ReleasePointer();
        }

        return arr;
    }

    public unsafe void WriteBytesFast(this MemoryMappedViewAccessor view, int offset, byte[] data)
    {
        try
        {
            byte* ptr = (byte*)0;
            _view.SafeMemoryMappedViewHandle.AcquirePointer(ref ptr);
            Marshal.Copy(data, 0, IntPtr.Add(new IntPtr(ptr), offset), data.Length);
        }
        finally
        {
            _view.SafeMemoryMappedViewHandle.ReleasePointer();
        }
    }
}