marker _ambulance_

\ ambulance -- version 3

: 2dup over over ;

: pillar    ( -- addr )  PORTA ;
: pillar#   ( -- addr )  PORTB ;
: pillar!   ( n -- )     pillar c! ;
: pillar#!  ( n -- )     pillar# c! ;   \ n in [0..7]

: limit-pillar#  ( n -- n' )  07 and ;

: initmojo ( -- )
    ff pillar  pin_output
    ff pillar# pin_output
    ff pillar!
    00 pillar#! ;
    
: all-blue 55 ;
: all-red  aa ;

variable speed   f0 speed !                   \ p#o gets only increased every SPEED
                                              \ steps of the (multiplexing) loop
: limit-counter  ( n -- n' )  speed @ mod ;   \ reset COUNTER if SPEED is reached

: ambulance  ( -- )
    initmojo
    0 0 0 ( cnt:counter p#o:pillar#-offset p#:pillar# )
    begin
        2dup                            = if all-blue pillar! then
        2dup   swap 4 + limit-pillar#   = if all-red pillar! then
        dup   pillar#!   1+ limit-pillar#  ( cnt p#o p#+1 )
        rot   1+ limit-counter             ( p#o p#+1 cnt+1 )   \ 0 increase counter
        dup 0= if rot 1+ limit-pillar# rot else rot rot then    \ increase p#o when cnt=0
    key3? until
    drop drop drop ;