// Tiny Encryption Algorithm.
// This code is placed into the public domain.

#light

open UInt32

let encode (v : uint32[]) (k : uint32[]) =
  let y = ref v.[0]
  let z = ref v.[1]
  let a = k.[0]
  let b = k.[1]
  let c = k.[2]
  let d = k.[3]
  let sum = ref 0u
  let delta = 0x9e3779b9u
  
  for i = 0 to 31 do
    sum := !sum + delta
    y := !y + ((!z <<< 4) + a ^^^ !z + !sum ^^^ (!z >>> 5) + b)
    z := !z + ((!y <<< 4) + c ^^^ !y + !sum ^^^ (!y >>> 5) + d)
  v.[0] <- !y
  v.[1] <- !z
  Printf.printf "v.[0] = %x; v.[1] = %x;\n" v.[0] v.[1]

let decode (v: uint32[]) (k : uint32[]) =
  let y = ref v.[0]
  let z = ref v.[1]
  let a = k.[0]
  let b = k.[1]
  let c = k.[2]
  let d = k.[3]
  let sum = ref 0xC6EF3720u
  let delta = 0x9E3779B9u
  
  for i = 0 to 31 do
    z := !z - ((!y <<< 4) + c ^^^ !y + !sum ^^^ (!y >>> 5) + d)
    y := !y - ((!z <<< 4) + a ^^^ !z + !sum ^^^ (!z >>> 5) + b)
    sum := !sum - delta
  v.[0] <- !y
  v.[1] <- !z
  Printf.printf "v.[0] = %x; v.[1] = %x;\n" v.[0] v.[1]