Keyboard: YESNO

       Name: YESNO                                                   [Show more]
       Type: Subroutine
   Category: Keyboard
    Summary: Wait until either "Y" or "N" is pressed
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * SVE calls YESNO
             * TBRIEF calls YESNO


 Returns:

   C flag               Set if "Y" was pressed, clear if "N" was pressed


.YESNO

 JSR t                  ; Scan the keyboard until a key is pressed, returning
                        ; the ASCII code in A and X

 CMP #'Y'               ; If "Y" was pressed, return from the subroutine with
 BEQ PL6                ; the C flag set (as the CMP sets the C flag, and PL6
                        ; contains an RTS)

 CMP #'N'               ; If "N" was not pressed, loop back to keep scanning
 BNE YESNO              ; for key presses

 CLC                    ; Clear the C flag

 RTS                    ; Return from the subroutine