[U-Boot] [PATCH v4 1/3] lib: add rand() function

Michael Walle michael at walle.cc
Fri May 11 23:20:15 CEST 2012


> please keep the ML on Cc: - thanks.
sorry wrong key

> In message <201205112249.27871.michael at walle.cc> you wrote:
> > > > > > +static unsigned int y = 2463534242U;
> > > > > 
> > > > > Hm... can we introduce at least a little entropy somewhere?
> > > > 
> > > > Mh? A user is supposed to seed via srand().
> > > 
> > > Then why initialize y at all?
> > 
> > To have a sane fallback. Maybe i should have written
> > 
> >  "A user is supposed to seed via srand() if he wan't some
> > 
> > entropy."
> 
> This is inconsequent.  Either we assume that the user will seed
> srand(), then y should not be initialized at all, so it goes to the
> BSS segment and does not waste space in the binary image.  Or we want
> to deal with cases where the user doesn call srand(), and then we
> should provide a bit better than such a static initialization.

Again, i wanted to stick with the regular rand() srand() semantics.

http://pubs.opengroup.org/onlinepubs/009695399/functions/rand.html
"If rand() is called before any calls to srand() are made, the same sequence 
shall be generated as when srand() is first called with a seed value of 1."

But i'm fine with removing the initialization.

-- 
Michael


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