Re: A86: Random Number stuff

[Prev][Next][Index][Thread]

Re: A86: Random Number stuff


Jimmy's random routine is very fast, and is great if you just want a single
random number every now and then. But if you for instance want to have
random coordinates chosen one after the other, it is not as good. I have
made a program to try out different random routines by taking random
coordinates and put out a sprite at the chosen location. With this routine
the results were something like this:

00 0
  0 00
     0 00
       0 0 0

All sprites were in an area from the upper left to the lower right. You will
get a little better results if you put a 'halt' between every call to the
random routine.

Another random routine using rom calls would be something like this:
(Should be correct)

xor a   ;ld a,0
call _setXXop1  ;content of a into OP1
ld a,10
call _setXXop2  ;content of a into OP2
call _randint   ;random integeter between OP1 and OP2->OP1
call _convop1   ;convert number in OP1 to 'a'

This routine would produce a random number between 0 and 10 into 'a'.
It is very random, but very slow.


Andreas Finne
a_finne@hotmail.com
a_finne@iobox.fi


>From: JayEll64@aol.com
>Reply-To: assembly-86@lists.ticalc.org
>To: assembly-86@lists.ticalc.org
>Subject: Re: A86: Random Number stuff
>Date: Sun, 9 Jan 2000 16:44:20 EST
>
>
>In a message dated 1/9/00 2:19:10 PM Mountain Standard Time,
>asmti86@hotmail.com writes:
>
> > I'm sure this has been asked before, but I'l ask anyway =) Is there a 
>way
>to
> >  call the rand function from assembly? If so how? All I could find in 
>the
>ASM
> >
> >  Studio 3.1 help file was _random, or is that what I should use? If 
>those
> >  don't work, is there an algorithim that can do this? I just need 
>something
> >  basic, like a random number 1-9. I could probably (try) to modify it 
>later
> >  if needed. Any help would be appreciated.
>
>Something like the following is all you should really need:
>
>;Randomization routine by Jimmy Mardell (used in ZTetris v3.0)
>PRandom:               ; Creates a pseudorandom number 0 <= x < A
>  ld b,a
>  ld a,r
>  add a,a
>  ld hl,0
>  ld d,0
>  ld e,a
>RMul:
>  add hl,de
>  djnz RMul
>  ld a,h
>  ret
>
>This could obviously be optimized if you have a constant range (ie, 0 <= x 
><
>9, and then increase the result to get a range of 1 to 9).
>
>JayEll
>

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
Follow-Ups: