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⌂ ∞ Elite on the BBC Micro and NES

Save and load: ResetSaveSlots

[NES version, Bank 6]

       Name: ResetSaveSlots                                          [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Reset the save slots for all eight save slots, so they will fail
             their checksums and get reset when they are next checked

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




.ResetSaveSlots

 LDX #7                 ; There are eight save slots, so set a slot counter in X
                        ; to loop through them all

.rsav1

 TXA                    ; Store the slot counter on the stack, copying the slot
 PHA                    ; number into A in the process

 JSR GetSaveAddresses   ; Set the following for save slot A:
                        ;
                        ;   SC(1 0) = address of the first saved part
                        ;
                        ;   Q(1 0) = address of the second saved part
                        ;
                        ;   S(1 0) = address of the third saved part

                        ; We reset the save slot by writing to byte #10 in each
                        ; of the three saved parts, so that this byte fails its
                        ; checksum, meaning the save slot will be reset the next
                        ; time it is checked in the CheckSaveSlots routine

 LDY #10                ; Set Y to use as an index to byte #10

 LDA #1                 ; Set byte #10 of the first saved part to 1
 STA (SC),Y

 LDA #3                 ; Set byte #10 of the second saved part to 3
 STA (Q),Y

 LDA #7                 ; Set byte #10 of the third saved part to 7
 STA (S),Y

 PLA                    ; Retrieve the slot counter from the stack into X
 TAX

 DEX                    ; Decrement the slot counter

 BPL rsav1              ; Loop back until we have reset the three parts for all
                        ; eight save slots

 RTS                    ; Return from the subroutine