> > Look carefully, and I think you'll figure out that the functions on 
> > the page referenced ARE implementations of Galois LFSRs.
> > Particularly clever implementations thereof that don't look 
> like they 
> > contain nearly enough instructions do so ...
> 
> The page also contains a few others that look a bit dodgy. I 
> was mainly aiming at the one at the top, that claims to 
> rotate with carry and to output that as random (AFAICT).


The problem with the rotate & carry routines is they repeat, eg after 65k
operations (16 bit register).  Not that you'd notice in most cases.

Also think about how to seed the routine, a way to cause the routine to jump
to a different spot in the sequence.  In other words, start the register at
a number, not 0.  Like in old BASIC games, where RANDOMIZE TIMER was used to
seed the routine.  (And it always gave the same sequence too for the same
seed.)

A typical method is that the routine always runs, and when the user presses
a button it outputs the current value in the sequence.  Ok for a dice
rolling app, not so good for something that doesn't have any inputs.

Tony

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist