-- Game of life routine macro. Made in August 2020.

local script = [[

; String-substitute frame and rState counters with more helpful names.
alias xx               fa
alias yy               fb
alias neighbors        fc
alias this_cell        fd


*   game_of_life

    ; Sets up the actor: finds the zone shape and copies dimensions to data table.
    init_zone_info
    
    goLabel g_loop
    
    
    ; Wait 1/4th of a second, then execute one GoL cycle.
    .g_loop
64  noop
    
    ; Count this cell's neighbors.
    set yy = get_zone_y
    while yy < get_zone_yh
        set xx = get_zone_x
        while xx < get_zone_xw
            set neighbors = 0
            
            ; Top-left
            set xx - 1
            set yy - 1
            position_self & set this_cell = resting_cell
            if this_cell == get_cell_on set neighbors + 1
            
            ; Top
            set xx + 1
            position_self & set this_cell = resting_cell
            if this_cell == get_cell_on set neighbors + 1
            
            ; Top-right
            set xx + 1
            position_self & set this_cell = resting_cell
            if this_cell == get_cell_on set neighbors + 1
            
            ; Left
            set yy + 1
            set xx - 2
            
            position_self & set this_cell = resting_cell
            if this_cell == get_cell_on set neighbors + 1
            
            ; Right (skip the middle)
            set xx + 2
            position_self & set this_cell = resting_cell
            if this_cell == get_cell_on set neighbors + 1
            
            ; Bottom-left
            set yy + 1
            set xx - 2
            
            position_self & set this_cell = resting_cell
            if this_cell == get_cell_on set neighbors + 1

            ; Bottom
            set xx + 1
            position_self & set this_cell = resting_cell
            if this_cell == get_cell_on set neighbors + 1

            ; Bottom-right
            set xx + 1
            position_self & set this_cell = resting_cell
            if this_cell == get_cell_on set neighbors + 1

            ; Return to center
            set xx - 1
            set yy - 1
            
            ; Write neighbor count to an array in the owning actor.
            set_neighbor_count
            
            ; Go to the next cell
            set xx + 1
        endwhile
        
        set yy + 1
    endwhile

    ; Start updating the cells based on neighbor information stored in the owning actor
    set yy = get_zone_y
    while yy < get_zone_yh
        set xx = get_zone_x
        while xx < get_zone_xw
            1    noop                                        ; Idle for one tick to make the update roll out gradually
            position_self & set this_cell = resting_cell     ; Position actor based on xx and yy counters. Get tile value from resting spot.
            get_neighbor_count                               ; Read in the neighbor count for this cell coordinate.
            if this_cell == get_cell_on
                ; log UPDATE LIVE CELL
                if neighbors < 2 or neighbors > 3
                    ; log (SETDEAD)
                    set resting_cell = get_cell_off
                endif
            else
                ;    log UPDATE DEAD CELL
                if neighbors == 3
                    ; log (SETLIVE)
                    set resting_cell = get_cell_on
                endif
            endif
            set xx + 1
        endwhile
        set yy + 1
    endwhile
    
    goLabel g_loop        ; Done execution, go back to idling.
]]