collapseos/arch/z80/sms/blk/615

: _updsel ( -- f, has an action button been pressed? )
    _status _prevstat C@ OVER = IF DROP 0 EXIT THEN
    DUP _prevstat C! ( changed, update ) ( s )
    0x01 ( UP ) OVER AND NOT IF 1 _sel +! THEN
    0x02 ( DOWN ) OVER AND NOT IF -1 _sel +! THEN
    0x04 ( LEFT ) OVER AND NOT IF -5 _sel +! THEN
    0x08 ( RIGHT ) OVER AND NOT IF 5 _sel +! THEN
    0x10 ( BUTB ) OVER AND NOT IF _nxtcls THEN
    ( update sel in VDP )
    _chk _sel C@ (emit) -1 XYPOS +!
    ( return whether any of the high 3 bits is low )
    0xe0 AND 0xe0 <
;