Controllers: SetControllerPast

       Name: SetControllerPast                                       [Show more]
       Type: Subroutine
   Category: Controllers
    Summary: Set the controller history variables to the values from four
             VBlanks ago
  Deep dive: Bolting NES controllers onto the key logger
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * UpdateJoystick calls SetControllerPast


.SetControllerPast

 LDA controller1B       ; If the B button is being held down, jump to past1 to
 BNE past1              ; zero the controller history variables, as we don't
                        ; need the controller history for the icon bar movement
                        ; (which is done by holding down the B button while
                        ; using the left and right buttons)

 LDA controller1Left    ; Set the high nibble of the left button history
 ASL A                  ; variable to bits 0 to 3 of controller1Left, so it
 ASL A                  ; contains the controller values from four VBlanks ago
 ASL A
 ASL A
 STA controller1Left03

 LDA controller1Right   ; Set the high nibble of the right button history
 ASL A                  ; variable to bits 0 to 3 of controller1Right, so it
 ASL A                  ; contains the controller values from four VBlanks ago
 ASL A
 ASL A
 STA controller1Right03

 RTS                    ; Return from the subroutine

.past1

 LDA #0                 ; Zero the controller history variables as we don't need
 STA controller1Left03  ; them for moving the icon bar pointer
 STA controller1Right03

 RTS                    ; Return from the subroutine