Yes, glibc in particular uses a very nice PRNG with 992 bits of internal state and good randomness of high and low bits, though it is not cryptographically stro

Yes, glibc in particular uses a very nice PRNG with 992 bits of internal state and good randomness of high and low bits, though it is not cryptographically strong like /dev/urandom. I don't know what one gets on Windows, but from the graph it looks like it's got some tricky squaring thing in it that turns out not to be very good.