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⌂ ∞ Elite on the BBC Micro and NES

Save and load: ClearNameInMiddle

[NES version, Bank 6]

       Name: ClearNameInMiddle                                       [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Remove the commander name from the middle column

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




 Arguments:

   A                    The slot number to clear in the middle column (0 to 7)



 Returns:

   A                    A is preserved



.ClearNameInMiddle

 LDX #11                ; Move the text cursor to column 11, so we print the
 STX XC                 ; name in the middle column of the screen

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

 ASL A                  ; Move the text cursor to row 6 + A * 2
 CLC                    ;
 ADC #6                 ; So this is the text row for slot number A in the
 STA YC                 ; middle column of the screen

 JSR GetRowNameAddress  ; Get the addresses in the nametable buffers for the
                        ; start of character row YC, as follows:
                        ;
                        ;   SC(1 0) = the address in nametable buffer 0
                        ;
                        ;   SC2(1 0) = the address in nametable buffer 1

 LDA SC                 ; Set SC(1 0) = SC(1 0) + XC
 CLC                    ;
 ADC XC                 ; So SC(1 0) is the address in nametable buffer 0 for
 STA SC                 ; the tile at cursor position (XC, YC)

 LDY #8                 ; We now want to print 8 spaces over the top of the slot
                        ; at (XC, YC), so set Y as a loop counter to count down
                        ; from 8

 LDA #0                 ; Set A = 0 to use as the pattern number for the blank
                        ; background tile

.cpos1

 STA (SC),Y             ; Set the Y-th tile of the slot in nametable buffer 0 to
                        ; the blank tile

 DEY                    ; Decrement the tile counter

 BPL cpos1              ; Loop back until we have blanked out every character
                        ; of the slot

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

 RTS                    ; Return from the subroutine