a->d[i]&=(~(1L<<j));
a->d[i]&=(~(((BN_ULONG)1)<<j));
int BN_clear_bit(BIGNUM *a, int n)	{	int i,j;	i=n/BN_BITS2;	j=n%BN_BITS2;	if (a->top <= i) return(0);	a->d[i]&=(~(1L<<j));	bn_fix_top(a);	return(1);	}