From: "robin" <robin51@dodo.com.au>
Subject: Re: Implementing the KISS4691 RNG
Date: Wed, 8 Sep 2010 13:15:27 +1000
Date: 2010-09-08T13:15:27+10:00 [thread overview]
Message-ID: <4c8753d5$0$45649$c30e37c6@exi-reader.telstra.net> (raw)
In-Reply-To: 93b6ca11-f4ae-4598-98f8-9a10be69ca3a@j18g2000yqd.googlegroups.com
"geo" <gmarsaglia@gmail.com> wrote in message news:93b6ca11-f4ae-4598-98f8-9a10be69ca3a@j18g2000yqd.googlegroups.com...
|
| For signed integers, flip the
| sign bits so that t<x becomes (t^m)<(x^m) or equivalents.
| (C versions using signed integers should also avoid the
| problem of right shifts, replacing (x>>19) by
| ((unsigned)x>>19) or ((unsigned)xs>>17) in the XS component.)
In the case of signed integers, both t<c AND t<x
must have their sign bits flipped, not just t<x.
Thus, the signed version in PL/I is:
(NOSIZE, NOFOFL):
RNG: PROCEDURE OPTIONS (MAIN, REORDER);
declare (xs initial (521288629), xcng initial (362436069),
Q(0:4690) ) static fixed binary (31);
MWC: procedure () returns (fixed binary (31));
declare (t,x,i) fixed binary (31);
declare (c initial (0), j initial (4691) ) fixed binary (31) static;
declare m fixed binary (31) static initial ((isll(1,31)));
if j < hbound(Q,1) then j = j + 1; else j = 0;
x = Q(j); t = isll(x,13) + c;
if ieor(t,m) < ieor(c,m) then
do; c = isrl(x, 19) + 1; t = t + x; end;
else
do; t = t + x; c = isrl(x, 19) + (ieor(t,m) < ieor(x,m)); end;
Q(j)=t;
return (t);
end MWC;
CNG: procedure returns (fixed binary (31));
xcng=bin(69069)*xcng+bin(123);
return (xcng);
end CNG;
XXS: procedure returns (fixed binary (31));
xs = ieor (xs, isll(xs, 13) );
xs = ieor (xs, isrl(xs, 17) );
xs = ieor (xs, isll(xs, 5) );
return (xs);
end XXS;
KISS: procedure returns (fixed binary (31));
return ( MWC()+CNG+XXS );
end KISS;
declare (i,x) fixed binary (31);
declare y fixed decimal (10);
Q = CNG + XXS; /* Initialize: */
do i = 1 to 1000000000; x=MWC(); end;
put skip edit (" Expected MWC result = 3740121002", 'computed =', x)
(a, skip, x(12), a, f(11));
y = iand(x, 2147483647);
if x < 0 then y = y + 2147483648;
put skip edit (y) (x(11), f(22)); put skip;
do i = 1 to 1000000000; x=KISS; end;
put skip edit ("Expected KISS result = 2224631993", 'computed =', x)
(a, skip, x(12), a, f(11));
y = iand(x, 2147483647);
if x < 0 then y = y + 2147483648;
put skip edit (y) (x(11), f(22));
end RNG;
prev parent reply other threads:[~2010-09-08 3:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <93b6ca11-f4ae-4598-98f8-9a10be69ca3a@j18g2000yqd.googlegroups.com>
2010-09-07 16:51 ` Implementing the KISS4691 RNG robin
2010-09-08 3:15 ` robin [this message]
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox