A-M baby

Task/Four-bit-adder/REXX/four-bit-adder.rexx

@@ -0,0 +1,35 @@
+/*REXX program shows (all) the sums of a full 4-bit adder  (with carry).*/
+call hdr1;  call hdr2
+
+   do j=0  for 16
+                              do m=0  for 4;   a.m=bit(j,m);   end
+      do k=0  for 16
+                              do m=0  for 4;   b.m=bit(k,m);   end
+      sc=4bitAdder(a.,b.)
+      z=a.3 a.2 a.1 a.0 '_+_' b.3 b.2 b.1 b.0 '_=_' sc ',' s.3 s.2 s.1 s.0
+      say translate(space(z,0),,'_')
+      end   /*k*/
+   end      /*j*/
+
+call hdr2;  call hdr1
+exit                                   /*stick a fork in it, we're done.*/
+
+/*──────────────────────────────────subroutines/functions───────────────*/
+hdr1:      say 'aaaa + bbbb = c, sum     [c=carry]';   return
+hdr2:      say '════   ════   ══════'              ;   return
+bit:       procedure;  arg x,y;  return substr(reverse(x2b(d2x(x))),y+1,1)
+
+/*──────────────────────────────────HALFADDER subroutine-───────────────*/
+halfAdder: procedure expose c;  parse arg x,y;   c=x & y;   return x && y
+
+/*──────────────────────────────────FULLADDER subroutine-───────────────*/
+fullAdder: procedure expose c;  parse arg x,y,fc
+_1=halfAdder(fc,x);  c1=c
+_2=halfAdder(_1,y);  c=c | c1;  return _2
+
+/*──────────────────────────────────3BITADDER subroutine-───────────────*/
+4bitAdder: procedure expose s. a. b.;  carry.=0
+                    do j=0 for 4;      n=j-1
+                    s.j=fullAdder(a.j, b.j, carry.n);   carry.j=c
+                    end   /*j*/
+return c