/* This is equivalent to `b->bits[idx] &= ~mask' except that it
is guaranteed to be atomic on a uniprocessor machine. See
the description of the AND instruction in [IA32-v2a]. */
/* This is equivalent to `b->bits[idx] &= ~mask' except that it
is guaranteed to be atomic on a uniprocessor machine. See
the description of the AND instruction in [IA32-v2a]. */