application/octet-stream
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1.12 KB
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39 lines
;;; Nujel - Copyright (C) 2020-2021 - Benjamin Vincent Schulenburg
;;; This project uses the MIT license, a copy should be included under /LICENSE
;;;
;;; A very simple pseudo random number generator, suitable for the illusion of
;;; randomness
(def seed 0)
(defn rng! ()
:export
(set! seed (+ 12345 (* seed 1103515245)))
(bit-or (bit-shift-left (bit-and seed #xFFFF) 16)
(bit-and (bit-shift-right seed 16) #xFFFF)))
(defn seed! (new-seed)
:export
"Set a new seed value for the RNG"
(set! seed new-seed))
(defn seed ()
:export
"Return the current RNG seed value"
(return seed))
(defn random (max)
:export-as int
"Return a value from 0 to MAX, or, if left out, a random int"
(if max
(rem (abs (rng!)) max)
(rng!)))
(defn seed-initialize! ()
:export
(set! seed (bit-xor (time) (time/milliseconds))))
(seed-initialize!)
(deftest #t (int? (random/int)))
(deftest #t (random/seed! 123) (def first-value (random/int)) (random/seed! 123) (= first-value (random/int)))
(deftest #t (random/seed! 99) (not= (random/int) (random/int)))
