# Add 4 + 9 = 13 on a counter machine, clocked by repeated cup expansions.
#
# export TERMINFO="$PWD"; tic add.txt; TERM=add; yes 'cup 0 0' | head -n 20 | tput -S

#   0: A=4, B=9, Z=1
#   1: JZDEC B,3,2    # block 1: if B is empty, halt
#   2: INC A,1        # block 2: move one unit from B into A
#   3: HALT           # block 3

add,cup=

# if      (Z == 0) { A = 4; B = 9; Z = 1 }
    %?%gZ%{0}%=%t
        %{4}%PA
        %{9}%PB
        %{1}%PZ

# else if (Z == 1) { if (B == 0) { Z = 3 } else { B = B-1; Z = 2 } }
    %e%gZ%{1}%=%t
        %?%gB%{0}%=%t
            %{3}%PZ
        %e
            %gB%{1}%-%PB
            %{2}%PZ
        %;

# else if (Z == 2) { A = A + 1; Z = 1 }
    %e%gZ%{2}%=%t
        %gA%{1}%+%PA
        %{1}%PZ

# else if (Z == 3) { HALTED }
    %e%gZ%{3}%=%t
    %;

# print the trace after executing this expansion
    Z=%gZ%d A=%gA%d B=%gB%d\n,