.PS # Adder.m4 log_init del = linewid/4 [ # full adder using gates A: dot; {"\sf A" rjust}; line right Xor1: XOR_gate with .In1 at Here dy = Xor1.In1.y-Xor1.In2.y B: dot(at (A,Xor1.In2)); {"\sf B" rjust}; line to Xor1.In2 line from Xor1.Out right 2*del+dy Xor2: XOR_gate with .In1 at Here Co: Autologix(Or(And(X1,X2),And(A,B)),N) with .nw at Xor2.sw+(-del,-del/2) line from Co.In1 to (Co.In1,Xor2.In2) then to Xor2.In2 dot(at (Xor1.Out+(del,0))); line to (Here,Co.In2) then to Co.In2 dot(at (Xor1.In1-(del,0))); line to (Here,Co.In3) then to Co.In3 dot(at (Xor1.In2-(del+dy,0))); line to (Here,Co.In4) then to Co.In4 line right del from Co.Out1; dot; {"\sf Co" ljust } dot(at (Here,Xor2.Out)); {"\sf S" ljust}; line to Xor2.Out Ci: dot(at (B,(0.5 between Xor2.s and Co.n))); line to (Co.In1,Here); dot "\sf Ci" rjust at Ci ] [ # truth table griddim = linewid*0.4 define(row',T: (0,-($1')*griddim*0.8) Loopover_(v',"\sf v" at T; T: T+(griddim,0)', shift($@))') [row(0,A,B,Ci,Co,S)] line thick 2 color "gray" right 4.5*griddim \ with .c at last [].c+(0,-griddim/2) [row(1,0,0,0,0,0) row(2,0,0,1,0,1) row(3,0,1,0,0,1) row(4,0,1,1,1,0) row(5,1,0,0,0,1) row(6,0,1,1,0,0) row(7,1,1,0,1,0) row(8,1,1,1,1,1) ] with .n at last [].c+(0,-griddim) ] with .nw at 1st [].ne+(linewid,0) [ # cascade of n-bit adders define(nbitadder', FlipFlopX(wid 2*linewid fill_(0.9), $n$-\sf\scriptsize bit" "\sf\scriptsize adder, :, I:;I:;;;I:;I:, I:, O:;;;O: ) $3' "\ldots"' at last [].Chip.n + (0,arrowht) "\ldots"' at last [].Chip.s - (0,arrowht) ifelse($1',,, "$\;\;x_{$1}$" at last [].N6.end above "$s_'{$1}$" at last [].S4.end below "$y_{$1}\;\;$" at last [].N5.end above') ifelse($2',,, "$\quad{}x_{$2}$" at last [].N2.end above "$y_{$2}\quad\;\;$" at last [].N1.end above "$s_'{$2}$" at last [].S1.end below ') ') P: nbitadder(0,n{-}1) {"$c_o$" at P.E1.end ljust } {"$c_n$" at P.W1.end above } Q: nbitadder(n,2n{-}1, with .E1.end at P.W1.end) arrow left arrowht from Q.W1.end ht arrowht*4/5 wid arrowwid*5/4 { "\ldots" at Here+(-10pt__,0) } R: nbitadder(,kn{-}1, with .E1.end at Here-(20bp__,0)) arrow left arrowht from R.W1.end ht arrowht*4/5 wid arrowwid*5/4 {"$c_{kn}\$" rjust } ] with .nw at 1st [].sw+(0,-0.5) .PE