"{ Package: 'stx:libbasic2' }"

"{ NameSpace: Smalltalk }"

Object subclass:#RandomKISS

	instanceVariableNames:'x y z c'

	classVariableNames:''

	poolDictionaries:''

	category:'Magnitude-Numbers-Random'

!

!RandomKISS class methodsFor:'documentation'!

documentation

"

    Warning: this generator should not be used for cryptographic work.

    NO WARRANTY

    KISS combines a linear congruence, XorShift and Lag with carry generator.

    The idea is from George Marsaglia.

    RandomKISS new nextInteger

    (RandomKISS new:5489) nextInteger

    If heavily used, it may be useful to embed the original C code as inline C code for a big speedup)

    Please read:

        Wikipedia article on KISS http://de.wikipedia.org/wiki/KISS_(Zufallszahlengenerator)

        http://de.wikipedia.org/wiki/Liste_von_Zufallszahlengeneratoren

        http://eprint.iacr.org/2011/007.pdf  (KISS is not cryptographically secure)

    [see also:]

        http://www0.cs.ucl.ac.uk/staff/d.jones/GoodPracticeRNG.pdf

        RandomGenerator - the default; uses the machine's /dev/random if available

        Random  - fast, but generates less quality random numbers

        RandomTT800 - another random generator

        RandomParkMiller - another random generator

        RandomMT19937 - another random generator

    [author:]

        Ported to Smalltalk by Claus Gittinger.

"

! !

!RandomKISS class methodsFor:'instance creation'!

new

    ^ self basicNew 

        initialize;

        seed:(Random randomSeed bitAnd:16rFFFFFFFF)

!

new:seed

    ^ self basicNew 

        initialize;

        seed:seed

! !

!RandomKISS methodsFor:'initialization'!

initialize

    x := 123456789. "/ <- any seed !!= 0

    y := 362436000.

    z := 521288629.

    c := 7654321.

!

seed:seed

    self assert:(seed ~= 0).

    x := seed.

! !

!RandomKISS methodsFor:'random numbers'!

nextBoolean

    "generates a boolean random"

    ^ self nextInteger > 16r7FFFFFFF

!

nextInteger

    "generates the next integer in 0..FFFFFFFF"

    |t|

    "/ Linear Congruencegenerator

    x := (69069 * x) + 12345.

    x := x bitAnd:16rFFFFFFFF.

    "/ Xorshift

    y := y bitXor:(y << 13).

    y := y bitXor:(y >> 17).

    y := y bitXor:(y << 5).

    y := y bitAnd:16rFFFFFFFF.

    "/ Multiply-with-carry

    t := (698769069 * z) + c.

    c := t >> 32.

    z := t bitAnd:16rFFFFFFFF.

    ^ (x + y + z) bitAnd:16rFFFFFFFF

! !

!RandomKISS class methodsFor:'documentation'!

version

    ^ '$Header$'

!

version_CVS

    ^ '$Header$'

! !