[sdiy] Best software noise algorithm?

[Tom Wiltshire]

Hi All,

What's the most efficient software pseudo-random noise algorithm?

I have previously used LFSRs, which are reasonably quick and can  
produce very long sequences quite easily, but I'm looking for  
something really quick and dirty.

I looked into Linear Congruential Generators, and found lots of sites  
that said that these can be very quick if you ensure the modulus is a  
power of two. But most examples are actually with the Parks-Miller  
numbers, which aren't a power of two.

I'll be doing this in dsPIC assembly as usual, and I've currently got  
a 64-bit LFSR that generates a new 16-bit number in 19 cycles. The  
quality and sequence length of that are more than I really need, so  
I'd like to speed it up.

Have people got any good tricks to share for making random numbers  
quickly ?

Thanks,
Tom