乘加器

Subtraction by e becomes addition with its one’s complement plus 1.
Subtraction by f becomes addition with its one’s complement plus 1.
~e and ~f take priority to be summed since they should arrive earlier than the MULT_P outputs.
Two’s complement inversion of e and f generates two ‘1’s. Adding these two ‘1’s costs zero area
since the addition is accomplished by connecting two Cin inputs to Logic1.
Unused Cin inputs are connected to Logic0.