#define IB1 1
#define IB2 2
#define IB5 16
#define IB18 131072

int irbit1(unsigned long *iseed)
{
	unsigned long newbit;

	newbit = (*iseed & IB18) >> 17
		^ (*iseed & IB5) >> 4
		^ (*iseed & IB2) >> 1
		^ (*iseed & IB1);
	*iseed=(*iseed << 1) | newbit;
	return (int) newbit;
}
#undef IB1
#undef IB2
#undef IB5
#undef IB18
/* (C) Copr. 1986-92 Numerical Recipes Software $!6)D$|2$3. */