Anonymous user
Elementary cellular automaton: Difference between revisions
m
→{{header|Racket}}: Better code formatting
(Updated D entry) |
m (→{{header|Racket}}: Better code formatting) |
||
Line 890:
=={{header|Racket}}==
This is the base code for the three elementary CA tasks. The "wrap" code
is a little over-complicated for the simple cases of wrapping on word
boundaries and for CA's with a narrower word. However, it will be used
unmodified for [[Elementary cellular automaton/Infinite length]].
<lang racket>#lang racket
Line 905 ⟶ 908:
(define (shift-left-1-bit-with-msb-R n R)
(fxior (fxand usable-bits/mask (fxlshift n 1
(if (bitwise-bit-set? R usable-bits/fixnum-1) 1 0)))
(define ((CA-next-bit-state rule) L n R)
(for/fold (
(
(define bit.2 (if (bitwise-bit-set? (shift-right-1-bit-with-lsb-L L n) b) 4 0))
(define bit.1 (if (bitwise-bit-set? n b) 2 0))
(define bit.0 (if (bitwise-bit-set? (shift-left-1-bit-with-msb-R n R) b) 1 0))
(define rule-bit (fxior bit.2 (fxior bit.1 bit.0)))
;; CA-next-generation generates a function which takes:
Line 930 ⟶ 934:
;; offset- : a new value for offset (it will have decreased since the CA grows to the left
;; with offset, and to the right with (length v-out)
(define (CA-next-generation rule #:wrap-rule (wrap-rule
(define next-state (CA-next-bit-state rule))
(lambda (v-in offset)
(define vl-1 (fx- (fxvector-length v-in) 1))
(define-values
(define rv
(for/fxvector ([l (in-sequences (in-value (fxvector-ref v+ v+l-1)) (in-fxvector v+))]
[r (
(
(values rv offset-)))
Line 967 ⟶ 970:
(display (~a #:width sig-bits #:align 'right #:pad-string "0"
(number->string (fxvector-ref v 0) 2))))
(for (
(display (~a #:width usable-bits/fixnum #:align 'right #:pad-string "0" (number->string n 2)))))
(module+ main
(define ng/122/19-bits (CA-next-generation 122 #:wrap-rule (wrap-rule-truncate-left-word 19)))
(for/fold (
(show-automaton v #:step step #:sig-bits 19)
(newline)
| |||