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Elementary cellular automaton/Random number generator: Difference between revisions

Elementary cellular automaton/Random number generator (view source)

Revision as of 17:13, 9 March 2015

68 bytes removed ,  9 years ago
m
→‎{{header|Racket}}: Improve code layout
(→‎{{header|Racket}}: conforming output)
m (→‎{{header|Racket}}: Improve code layout)
Line 227:
 
<lang racket>#lang racket
;; below is the code from the parent task
(require "Elementary_cellular_automata.rkt")
(require racket/fixnum)
Line 233:
;; This is the RNG automaton
(define (CA30-random-generator
#:rule ([rule 30)] ; rule 30 is random, maybe you're interested in using others
;; width of the CA... this is implemented as a number of words plus, maybe, another word
;; maybe, another word containing the spare bits
#:bits ([bits 256)])
(let*define-values (([full-words more-bits] (quotient/remainder bits usable-bits/fixnum))
(quotient/remainder bits usable-bits/fixnum))
([wrap-rule] (and (positive? more-bits) (wrap-rule-truncate-left-word more-bits)))
(define (nextwrap-word)rule▼
([next-gen] (CA-next-generation 30 #:wrap-rule wrap-rule))▼
(and ([v]positive? (makemore-fxvectorbits) (+ fullwrap-rule-words (iftruncate-left-word more-bits 1 0)))))
▲ (define ([next-gen] (CA-next-generation 30 #:wrap-rule wrap-rule))
(define v (make-fxvector (+ full-words (if more-bits 1 0))))
(fxvector-set! v 0 1) ; this bit will always have significance
 
▲ (define (next-word)
(define-values (v+ o) (next-gen v 0)word)
(define-values [v+ o] (next-gen v 0))
(begin0
(begin0 (fxvector-ref v 0) (set! v v+)))
 
(set! v v+)))
(lambda (bits)
(lambdafor/fold ([acc 0]) ([_ (in-range bits)])
;; the CA is fixnum, but this function returns integers of arbitrary width▼
(for/fold ((acc 0)) ((_ (in-range bits)))
(bitwise-ior (arithmetic-shift acc 1) (bitwise-and (next-word) 1))))))▼
▲ ;; the CA is fixnum, but this function returns integers of arbitrary width
▲ (bitwise-ior (arithmetic-shift acc 1) (bitwise-and (next-word) 1))))))
 
(module+ main
Line 260 ⟶ 259:
(define C30-rand-64 (CA30-random-generator #:bits 64))
;; this should be the list from "C"
(for/list (([i 10)]) (C30-rand-64 8))
 
; we also do big numbers...
(number->string (C30-rand-64 256) 16)
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