80 lines
2.1 KiB
Factor
80 lines
2.1 KiB
Factor
! Copyright (C) 2005, 2008 Doug Coleman.
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! See http://factorcode.org/license.txt for BSD license.
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! mersenne twister based on
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! http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/MT2002/CODES/mt19937ar.c
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USING: accessors alien.c-types alien.data fry init kernel math
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math.bitwise namespaces random sequences sequences.private
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specialized-arrays system ;
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SPECIALIZED-ARRAY: uint
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IN: random.mersenne-twister
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<PRIVATE
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TUPLE: mersenne-twister { seq uint-array } { i fixnum } ;
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CONSTANT: n 624
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CONSTANT: m 397
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CONSTANT: a uint-array{ 0 0x9908b0df }
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: mt-step ( k+m k+1 k seq -- )
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[
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[ nth-unsafe ] curry tri@
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[ 31 bits ] [ 31 mask-bit ] bi* bitor
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[ 2/ ] [ 1 bitand a nth ] bi bitxor bitxor
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] 2keep set-nth-unsafe ; inline
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: mt-steps ( k+m k+1 k n seq -- )
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[ mt-step ] curry [ 3keep [ 1 + ] tri@ ] curry times 3drop ; inline
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: mt-generate ( mt -- )
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[
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seq>>
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[ [ m 1 0 n m - ] dip mt-steps ]
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[ [ 0 n m - 1 + n m - m 1 - ] dip mt-steps ]
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[ [ m 1 - 0 n 1 - ] dip mt-step ]
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tri
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] [ 0 >>i drop ] bi ; inline
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: init-mt-formula ( i seq -- f(seq[i]) )
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dupd nth dup -30 shift bitxor 1812433253 * + 1 w+ ; inline
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: init-mt-rest ( seq -- )
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n 1 - swap '[
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_ [ init-mt-formula ] [ [ 1 + ] dip set-nth ] 2bi
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] each-integer ; inline
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: init-mt-seq ( seed -- seq )
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32 bits n uint <c-array>
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[ set-first ] [ init-mt-rest ] [ ] tri ; inline
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: mt-temper ( y -- yt )
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dup -11 shift bitxor
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dup 7 shift 0x9d2c5680 bitand bitxor
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dup 15 shift 0xefc60000 bitand bitxor
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dup -18 shift bitxor ; inline
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: next-index ( mt -- i )
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dup i>> dup n < [ nip ] [ drop mt-generate 0 ] if ; inline
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PRIVATE>
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: <mersenne-twister> ( seed -- obj )
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init-mt-seq 0 mersenne-twister boa
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dup mt-generate ;
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M: mersenne-twister seed-random
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init-mt-seq >>seq
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dup mt-generate ;
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M: mersenne-twister random-32*
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[ next-index ]
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[ seq>> nth-unsafe mt-temper ]
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[ [ 1 + ] change-i drop ] tri ;
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: default-mersenne-twister ( -- mersenne-twister )
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nano-count <mersenne-twister> ;
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[
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default-mersenne-twister random-generator set-global
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] "bootstrap.random" add-startup-hook
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