Shouldn't be too hard using Linq...

using System.Linq;

[Microsoft.SqlServer.Server.SqlFunction(FillRowMethodName = "clrNGLoop_FillRow", TableDefinition = "Position int, Token nvarchar(4000)")]

public static IEnumerable clrNGLoop(SqlString value, SqlInt32 n)

{

int idx = 1;

Lookup<int, char> l = (Lookup < int, char> )value.Value.ToLookup(x => idx++, y => y);

return l.Select(x => new Item() { Position = x.Key, Token = new string(l.Where(y => y.Key >= x.Key && y.Key < (x.Key + n.Value)).Select(z => z.First()).ToArray()) }).Where(v=>v.Token.Length == n.Value);

}

public static void clrNGLoop_FillRow(Object obj, out SqlInt32 position, out SqlString token)

{

Item item = (Item)obj;

position = new SqlInt32(item.Position);

token = new SqlString(item.Token);

}

public class Item

{

public int Position;

public string Token;

}