utils.mligo

(**
    Utility functions
    To be cleaned
    @author Maxime Niankouri - PlayMakers - 2023
    @version 1.0.0
*)
let rec _sqrt (n:int) (s:int) : int = if s*s > n then s-1 else _sqrt n (s+1)
let sqrt (n: int) : int = _sqrt n 1

let random (s0: nat) (s1: nat) = 
  let s1 =  s1 lxor (s1 lsl 23n) in 
  let s1 =  s1 lxor (s1 lsr 17n) in 
  let s1 =  s1 lxor s0 in 
  let s1 =  s1 lxor (s0 lsr 26n) in 
  s0 + s1

// Converts a supposedly random byte into a random nat (0-255)
let byte_to_nat (b: bytes) : nat =
  let i : int = Option.unopt(Bytes.unpack (Bytes.concat 0x0500 (
    if b < 0x80 then b else (Bytes.concat b 0x01) )))
  in abs (i+128)

let rec _bytes_to_nat (b, acc: bytes * nat) : nat =
  let s = Bytes.length b in
  if s = 0n then acc else
  if s = 1n then 256n*acc + byte_to_nat b else
  let acc = 256n * acc + (byte_to_nat ((Bytes.sub 0n 1n b))) in
  _bytes_to_nat ((Bytes.sub 1n (abs (s-1n)) b), acc)

let bytes_to_nat (b: bytes) : nat = _bytes_to_nat (b,0n)

[@inline]
let rand_hash () : bytes = 
  let f = 
  [%Michelson
    ({|{
        PUSH mutez 0; NONE key_hash;
        CREATE_CONTRACT {parameter unit; storage unit; code {CDR; NIL operation; PAIR}};
        DROP
    }|}
    : unit -> address)
  ]
  in Bytes.sub 10n 17n (Bytes.pack (f ()))

let rand_hash_as_nat () : nat = bytes_to_nat (rand_hash ())