debounce.bas

 dim rand16 = z

 dim sw = d
 dim debounce = e
 dim jf = f
 dim cntr = g

 gosub clear

 COLUPF = $4A
 COLUBK = $42

 debounce = $00

main

 if cntr <> 32 then skip_fire

  temp1 = ((jf ^ $80) | INPT4) & $80 : jf = INPT4
  if temp1 then goto draw
  cntr = 0

skip_fire
 sw = 0
 if cntr & $08 then sw = sw - 1
 temp1 = (cntr ^ $04) & $04
 if temp1 then sw = rand
 gosub debounce

 if cntr & $08 then pfpixel cntr 0 on else pfpixel cntr 0 off
 if sw & 1 then pfpixel cntr 1 on else pfpixel cntr 1 off
 if debounce & 1 then pfpixel cntr 2 off else pfpixel cntr 2 on

 if c & 1 then pfpixel cntr 4 on else pfpixel cntr 4 off
 if b & 1 then pfpixel cntr 5 on else pfpixel cntr 5 off
 if a & 1 then pfpixel cntr 6 on else pfpixel cntr 6 off

 cntr = cntr + 1

draw
 drawscreen
 goto main




debounce
 temp1 = sw ^ debounce

 rem reset counter
 b = b | temp1
 a = a | temp1

 rem increment counter
 b = b ^ a
 a = a ^ $FF

 rem if the counter has counted to three toggle debounce
 debounce = (b & a) ^ debounce
 return

clear
 playfield:
 ................................
 ................................
 ................................
 ................................
 ................................
 ................................
 ................................
 ................................
 ................................
 ................................
 ................................
 ................................
end
 return