[@@@ifge 4.12]

include Atomic

[@@@else_]

open Stdlib (* for == *)

type 'a t = { mutable x: 'a }

let[@inline] make x = { x }
let[@inline] get { x } = x
let[@inline] set r x = r.x <- x

let[@inline never] exchange r x =
  (* atomic *)
  let y = r.x in
  r.x <- x;
  (* atomic *)
  y

let[@inline never] compare_and_set r seen v =
  (* atomic *)
  if r.x == seen then (
    r.x <- v;
    (* atomic *)
    true
  ) else
    false

let[@inline never] fetch_and_add r x =
  (* atomic *)
  let v = r.x in
  r.x <- x + r.x;
  (* atomic *)
  v

let[@inline never] incr r =
  (* atomic *)
  r.x <- 1 + r.x
(* atomic *)

let[@inline never] decr r =
  (* atomic *)
  r.x <- r.x - 1
(* atomic *)

[@@@endif]