47 lines
1.2 KiB
Factor
47 lines
1.2 KiB
Factor
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! Copyright (C) 2011 John Benediktsson
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! See http://factorcode.org/license.txt for BSD license
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USING: accessors arrays ascii kernel locals math random
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sequences sequences.extras vectors ;
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IN: enigma
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: <alphabet> ( -- seq )
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26 iota >array ;
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: <cog> ( -- cog )
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<alphabet> randomize ;
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: <reflector> ( -- reflector )
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<alphabet> dup length iota >vector [ dup empty? ] [
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[
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[ delete-random ] [ delete-random ] bi
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pick exchange
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] keep
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] until drop ;
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TUPLE: enigma cogs prev-cogs reflector ;
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: <enigma> ( num-cogs -- enigma )
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[ <cog> ] replicate dup clone <reflector> enigma boa ;
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: reset-cogs ( enigma -- enigma )
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dup prev-cogs>> >>cogs ;
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: special? ( n -- ? )
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[ 25 > ] [ 0 < ] bi or ;
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:: encode ( text enigma -- cipher-text )
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0 :> ln!
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enigma cogs>> :> cogs
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enigma reflector>> :> reflector
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text >lower [
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CHAR: a mod dup special? [
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ln 1 + ln!
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cogs [ nth ] each reflector nth
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cogs reverse [ index ] each CHAR: a +
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cogs length iota [ 6 * 1 + ln mod zero? ] filter
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cogs [ unclip prefix ] change-nths
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] unless
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] map ;
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