Save and load: DrawSaveSlotMark

       Name: DrawSaveSlotMark                                        [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Draw a slot mark (a dash) next to a saved slot
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * SVE calls DrawSaveSlotMark


 Arguments:

   Y                    The save slot number (0 to 7)

   CNT                  The offset of the first free sprite in the sprite buffer


 Returns:

   Y                    Y is preserved


.DrawSaveSlotMark

 STY YSAV2              ; Store Y in YSAV2 so we can retrieve it below

 LDY CNT                ; Set Y to the offset of the first free sprite in the
                        ; sprite buffer

 LDA #109               ; Set the pattern number for sprite Y to 109, which is
 STA pattSprite0,Y      ; the dash that we want to use for the slot mark

 LDA XC                 ; Set the x-coordinate for sprite Y to XC * 8
 ASL A                  ;
 ASL A                  ; As each tile is eight pixels wide, this sets the pixel
 ASL A                  ; x-coordinate to tile column XC
 ADC #0
 STA xSprite0,Y

 LDA #%00100010         ; Set the attributes for sprite Y as follows:
 STA attrSprite0,Y      ;
                        ;   * Bits 0-1    = sprite palette 2
                        ;   * Bit 5 set   = show behind background
                        ;   * Bit 6 clear = do not flip horizontally
                        ;   * Bit 7 clear = do not flip vertically

 LDA YC                 ; Set the y-coordinate for sprite Y to 6 + YC * 8
 ASL A                  ;
 ASL A                  ; As each tile is eight pixels tall, this sets the pixel
 ASL A                  ; y-coordinate to the sixth pixel line within tile row
 ADC #6+YPAL            ; YC
 STA ySprite0,Y

 TYA                    ; Set CNT = Y + 4
 CLC                    ;
 ADC #4                 ; So CNT points to the next sprite in the sprite buffer
 STA CNT                ; (as each sprite takes up four bytes in the buffer)

 LDY YSAV2              ; Restore the value of Y that we stored in YSAV2 above
                        ; so that Y is preserved

 RTS                    ; Return from the subroutine