Modify Figure 6-23 or Figure 6-24 to make it a 12-bit adder without using constants.

Figure 6-23

Figure 6-24

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123 10 10 5 6 7 8 9 10 11 4 b[7..0] 23 12 SUBDESIGN fig6_23 13 14 ( a [7..0] s [8..0] ) : INPUT; : INPUT; : OUTPUT: VARIABLE aa [8..0] bb [8..0] BEGIN aa [8..0] = (GND, a [7..0]); bb [8..0] (GND, b[7..0]); s [8..0] = aa[8..0] + bb [8..0]; END; :NODE; :NODE; -- -- -- -- -- -- 8-bit augend 8-bit addend 9-bit sum expanded augend expanded addend concatenate leading zero to both operands add expanded operands