Fast C random boolean generator

I'm interested in generating fast random booleans (or equivalently a Bernoulli(0.5) random variable) in C. Of course if one has a fast random generator with a decent statistical behaviour the problem "sample a random Bernoulli(0.5)" is easily solved: sample x uniformly in (0,1) and return 1 if x<0.5, 0 otherwise.

Suppose speed is the most important thing, now I have two questions/considerations:

1. Many random doubles generators first generate an integer m uniformly in a certain range [0,M] and then simply return the division m/M. Wouldn't it be faster just to check whether m < M/2 (here M/2 is fixed, so we are saving one division)

   2. Is there any faster way to do it? At the end, we're asking for way less statistical properties here: we're maybe still interested in a long period but, for example, we don't care about the uniformity of the distribution (as long as roughly 50% of the values are in the first half of the range).