application/octet-stream
•
1.12 KB
•
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]]]
