That is marvellous!!!
J.E.B.
On 11/28/18 5:42 PM, Will Godfrey wrote:
For some time now I've been unhappy with the way we handle random numbers. The--
whole thing was a dogs breakfast of adjustments and patches - well rather less
so now :)
By using the Linux random_r() function, we lost portability and the patch for
BSD created a potential problem for multiple instances, so I started a search
for one that was truly portable and able to be built into Yoshimi. It doesn't
seem that anyone else tried to do this, as I quite quickly found the Bob Jenkins
"A Small Noncryptographic PRNG" which he apparently publicised in 2007.
If you want to know more, and how well respected this is look here:
http://www.pcg-random.org/posts/bob-jenkins-small-prng-passes-practrand.html
So apart from portability, what do we get?
Well for a start, even unoptimised it's faster than the Linux built-in one.
It's really rather small.
You can pull 128 *TERABYTES* of numbers from it before it repeats. Even in my
test routine (with nothing else happening) that would take over an hour, so I
felt justified in significantly reducing the number of times it was re-seeded.
This in itself seems to have made a very tiny reduction in note-on time.
It's in the latest build :)
