Adds the fractions @a_n/@a_d and @b_n/@b_d and stores the result in @res_n and @res_d.
Numerator of first value
Denominator of first value
Numerator of second value
Denominator of second value
Pointer to #gint to hold the result numerator
Pointer to #gint to hold the result denominator
%FALSE on overflow, %TRUE otherwise.
See Implementation
Adds the fractions @a_n/@a_d and @b_n/@b_d and stores the result in @res_n and @res_d.