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From: ForthNet@willett.pgh.pa.us (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: Mathematical routines
Message-ID: <1722.UUL1.3#5129@willett.pgh.pa.us>
Date: 13 Sep 90 03:02:06 GMT
Organization: String, Scotch tape, and Paperclips.  (in Pgh, PA)
Lines: 49

Category 3,  Topic 10
Message 55        Wed Sep 12, 1990
D.RUFFER [Dennis]            at 00:29 EDT
 
Re: CHARLIE HITSELBERGER

 > My question is, is the " 0 BEGIN DROP " a commonly used thing for
 > loops that leave a value on the stack upon exit?

That is one way to do it Charlie.  Here is another:

 : DICE   ( -- n1 n2 )
     2 0
     DO
         BEGIN
             RANDU
             7 AND
             DUP
             6 < NOT
         WHILE
             DROP
         REPEAT
         1+
     LOOP
 ;

However, this method costs one more jump every time the loop repeats in place
of the literal you had that was executed once.  Of course, if your machine
does a */ with any reasonable speed, you might also try the following:

 : DICE   ( -- n1 n2 )
     2 0
     DO
         RANDU 6 256 */
     LOOP
 ;

Depending on how fast your random algorithm is and how often, on average, it
doesn't satisfy your test, this may actually be faster. In fact, if you are
out for absolute speed, get rid of the DO...LOOP in the above example and
you've done just about as much as you can. That is unless you want to re-code
RANDU to do the 8 bit MOD for you.  Then you would have:

 : DICE   ( -- n1 n2 )   6 RANDU  6 RANDU ;

Well, you asked.  <grin>   DaR
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