Alien 8: Routine at 51455

51455: Read Controls

Used by the routines at HandlePlayerLegs and HandleTurningLegs.

Reads the controls that the player is using and stores them in ControlsPressed. The controls are made into a byte, with bit 0 for left, bit 1 for right, bit 2 for walking forward, bit 3 for jumping and bit 4 for picking up and dropping an object. Bit 5 is set by ReadControls_Finish. No controls are read while the game over scene is shown or the game has been completed.

Output
C	The controls

Pick the reader from ControlMethod.

ReadControls

51455

LD A,(23331)

Fetch GameCompletedFlag.

51458

LD C,A

Copy it to C.

51459

LD A,(23332)

Fetch GameOverFlag.

51462

OR C

Merge C.

51463

LD C,0

Set C to 0.

51465

JP NZ,ReadControls_Finish

Jump to ReadControls_Finish if they are not zero.

51468

LD A,(23300)

Fetch ControlMethod.

51471

RRCA

Rotate bits 1 and 2 into bits 0 and 1.

51472

AND %00000011

Keep only bits 0 and 1.

51474

JP Z,ReadKeyboard

Jump to ReadKeyboard if they are zero.

51477

DEC A

Decrement A.

51478

JR Z,ReadKempstonJoystick

Jump to ReadKempstonJoystick if it is zero.

51480

DEC A

Decrement A.

51481

JR Z,ReadCursorJoystick

Jump to ReadCursorJoystick if it is zero.

Continue on to ReadInterface2Joystick.

View the equivalent code in;