require util.4th

1024 constant MAX_EVENTS

0
  cell +field event.id
  cell +field event.data
constant /EVENT

0 variable! current-event
0 variable! last-event

MAX_EVENTS /EVENT * constant EVENTS_SIZE
create events EVENTS_SIZE allot

: (translate) ( index-u -- event-addr )
  ]] /EVENT * events + [[ ; IMMEDIATE
: (wrap) ( index-u -- index-u )
  ]] MAX_EVENTS mod [[ ; IMMEDIATE
: (read) ( addr -- data-u id-u )
  ]] dup event.data @ swap event.id @ [[ ; IMMEDIATE
: (write) ( data-u id-u addr -- )
  ]] tuck event.id ! event.data ! [[ ; IMMEDIATE
: events.has-item? ( -- flag )
  current-event @ last-event @ <> ;
: events.enqueue ( data-u id-u -- )
  last-event @ dup 1+ dup >r current-event @ = abort" Queue is full."
  (translate) (write) r> (wrap) last-event ! ;
: events.dequeue ( -- data-u id-u )
  events.has-item? invert abort" No events in queue."
  current-event @ dup (translate) (read)
  rot 1+ (wrap) current-event ! ;
: events.clear ( -- )
  0 current-event !
  0 last-event !
  events EVENTS_SIZE erase ;

events.clear