module private Internal =
    let crcTable = 
        let inline nextValue acc =
            if 0u <> (acc &&& 1u) then 0xedb88320u ^^^ (acc >>> 1) else acc >>> 1
        let rec iter k acc =
            if k = 0 then acc else iter (k-1) (nextValue acc)
        [| 0u .. 255u |] |> Array.map (iter 8)


/// Returns the CRC-32 value of 'name' as specified by RFC1952
let crc32 (name:string) =
    let inline update acc (ch:char) =
        Internal.crcTable.[int32 ((acc ^^^ (uint32 ch)) &&& 0xffu)] ^^^ (acc >>> 8)
    0xFFffFFffu ^^^ Seq.fold update 0xFFffFFffu name