application/octet-stream
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1.26 KB
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40 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]
[export rng!
[defn random/rng! []
[set! seed [+ 12345 [* seed 1103515245]]]
[bit-or [bit-shift-left [bit-and seed #xFFFF] 16]
[bit-and [bit-shift-right seed 16] #xFFFF]]]]
[export seed!
[defn random/seed! [new-seed]
"Set a new seed value for the RNG"
[set! seed new-seed]]]
[export seed
[defn random/seed []
"Return the current RNG seed value"
[return seed]]]
[export int
[defn random [max]
"Return a value from 0 to MAX, or, if left out, a random int"
[if max
[rem [abs [random/rng!]] max]
[random/rng!]]]]
[export seed-initialize!
[defn random/seed-initialize! []
[set! seed [bit-xor [time] [time/milliseconds]]]]]
[random/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]]]
