Korg Poly800/EX800 Users

Actually, the more time I spend writing this code in assembler, the
more I realize how clever the guys who came up with C were. And I wish
I was doing this all in C.

The pseudo number generator is known as a Linear Congruential Random
Number Generator. You can all about it
http://www.daylight.com/meetings/emug98/Sayle/sample.html.

Since we're working in 8 bits, it's periodicity is short. And it could
be made to be much better than it is. I just got a result that sounded
OK and stayed with that. But I am sure that I will go back and revisit
this little code snippet and work on it some time.

Meanwhile, the equation looks like this.

Xn+1 = (aXn+c) mod m

And yes, all of the code that I have written is commented like that
and all of the original Korg code that I understand is commented like
that. Is there a problem with my commenting?

Mike


--- In korgpolyex@yahoogroups.com, Atom Smasher <atom@...> wrote:
>
> assembler?!?! i should have known.... and i've always considered C a
low 
> level language...
> 
> despite the verbose comments (is all of the code commented that
well?) i 
> can't follow it. can you give a brief explanation?
> 
> 
> 
> 
> On Thu, 18 Sep 2008, korgpolyex800 wrote:
> 
> > Here's my pseudo random number generator.
> >
> > It is by no means very random.
> >
> > ; my pseudo random number generator - used for the LFO randomiser
> > ; returns a random number in A
> >
> > RANDOMIZE:	push	h ; save HL
> > 		lxi	h, M_RANDOM ; point at the previous value (seed)
> > 		mov	a, m ; put the seed value into A
> > 		cpi	0 ; check for seed equals zero
> > 		jnz	RANDOMIZEA ; if seed is zero jump to randomizea
> > 		cma ; compliment A
> > 		mov	m, a ; put A back into seed
> > RANDOMIZEA:	rlc ; rotate left through carry
> > 		adi	43 ; add 43 offset
> > 		mov	m, a ; save in seed
> > 		pop	h ; load HL
> > 		ret ; return with pseudo random in A
> >
> > I would be more than happy for you to suggest something better as long
> > as it doesn't add any CPU cycles. :-)
> 
> 
> -- 
>          ...atom
> 
>   ________________________
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