%  Do an increment/decrement operation from one register to
%  another, possibly the same one.
%  #1   the source register select line
%  #2   the destination register load line
%  #3   optional dec line

inhibit_i
inhibit_i
inhibit_i
inhibit_i
#1   ld_inc    #3
#1             #3
#2   sel_inc   #3
     sel_inc   #3
0
reset inhibit_i