jetpac: Routine at 733f

733f: Check if fire button is pressed.

Used by the routine at 7492.

Output
A	fire button, $FE = pressed, $FF = no input - like joystick: 000LRDUF.

733f

ld a,($5cf3)

Game options

7342

bit 1,a

Use Joystick?

7344

jr nz,$7302

Jump if so

7346

ld b,$02

Loop count: read left and right row of keys

7348

ld a,$fd

Row: A,S,D,F,G

734a

out ($fd),a

Set port for reading keyboard

734c

in a,($fe)

...and read that row of keys

734e

and $1f

7350

cp $1f

Check if any keys on the row are pressed

7352

jr nz,$735b

Jump if so - key press detected

7354

ld a,$bf

Row: H,J,K,L,Enter

7356

djnz $734a

Loop back and read input again

7358

ld a,$ff

Still no input detected

735a

ret

735b

ld a,$fe

A=FIRE : 1111 1110

735d

ret