I’m not trying to be rude, but you don’t realize what’s going on here:
uuu is a bitmask:
‘uuu’ (or (1 << bits)-1 ) in “ret = rand_holder & uuu;“ , only puts the
lower ‘bit’ quantity of bits of rand_holder into ret, then it right shifts
rand_holder afterward to trash them every time in the loop when it’s done.
So if bits is 8, uuu is going to be 0xff
No, you aren't:
>
> > for (;;) {
> > if (rand_bits < bits) {
> > rand_holder |= ((uint64_t)arc4random()) <<
> > rand_bits;
> >
> > /*
> > * rand_bits will be a number between 0 and 31
> here
> > * so the 0x20 bit will be empty
> > * rand_bits += 32;
> > */
> > rand_bits |= 32;
> > }
> >
> > ret = rand_holder & uuu;
> > rand_holder >>= bits;
> > rand_bits -= bits;
> >
> > if (ret < upper_bound)
> > return ret;
> > }
>
> This isn't rejection sampling. This is reusing part of the rejected
> sample.
--
-Luke
