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⌂ ∞ Elite on the BBC Micro and NES

Controllers: WaitForNoDirection

[NES version, Bank 6]

       Name: WaitForNoDirection                                      [Show more]
       Type: Subroutine
   Category: Controllers
    Summary: Wait until the left and right buttons on controller 1 have been
             released and remain released for at least four VBlanks

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * MoveInMiddleColumn calls WaitForNoDirection
             * MoveInRightColumn calls WaitForNoDirection
             * MoveToLeftColumn calls WaitForNoDirection




 Returns:

   A                    A is preserved



.WaitForNoDirection

 PHA                    ; Store the value of A on the stack so we can restore it
                        ; at the end of the subroutine

.ndir1

 JSR SetupPPUForIconBar ; If the PPU has started drawing the icon bar, configure
                        ; the PPU to use nametable 0 and pattern table 0

 LDA controller1Left03  ; Keep looping back to ndir1 until both the left and
 ORA controller1Right03 ; right button on controller 1 have been released and
 BMI ndir1              ; remain released for at least four VBlanks

 PLA                    ; Restore the value of A that we stored on the stack, so
                        ; A is preserved

 RTS                    ; Return from the subroutine