Knight Lore: Routine at D077

D077: Read Kempston Joystick

Used by the routine at ReadControls.

Reads the controls from a Kempston joystick.

Output
C	The controls

Set each control bit from the Kempston port.

ReadKempstonJoystick

D077

IN A,($1F)

Read the joystick.

D079

LD C,$00

Set the controls to none.

D07B

BIT 0,A

Set the right control if the joystick is pushed right.

D07D

JR Z,ReadKempstonJoystick_TestLeft

D07F

SET 1,C

ReadKempstonJoystick_TestLeft

D081

BIT 1,A

Set the left control if the joystick is pushed left.

D083

JR Z,ReadKempstonJoystick_TestDown

D085

SET 0,C

ReadKempstonJoystick_TestDown

D087

BIT 2,A

Set the pick up control if the joystick is pushed down.

D089

JR Z,ReadKempstonJoystick_TestUp

D08B

SET 4,C

ReadKempstonJoystick_TestUp

D08D

BIT 3,A

Set the walk control if the joystick is pushed up.

D08F

JR Z,ReadKempstonJoystick_TestFire

D091

SET 2,C

ReadKempstonJoystick_TestFire

D093

BIT 4,A

Set the jump control if the fire button is pressed.

D095

JR Z,ReadKempstonJoystick_Done

D097

SET 3,C

ReadKempstonJoystick_Done

D099

JP ReadControls_Finish

Jump to ReadControls_Finish.

View the equivalent code in;