Save and load: SaveLoadCommander

       Name: SaveLoadCommander                                       [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Either save the commander from BUF into a save slot, or load the
             commander from BUF into the game and start the game
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * CopyCommanderToBuf calls SaveLoadCommander
             * MoveInMiddleColumn calls SaveLoadCommander


 Arguments:

   A                    The slot number to process:

                          * 0 to 7 = save the current commander from BUF into
                                     save slot A

                          * 9 = load the current commander from BUF into the
                                game and start the game


 Returns:

   A                    A is preserved


.SaveLoadCommander

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

 CMP #9                 ; If A = 9 then this is the current commander in the
 BEQ scom2              ; left column, so jump to scom2 to load the commander
                        ; in BUF into the game

                        ; If we get here then this is one of the save slots on
                        ; the right of the screen and A is in the range 0 to 7,
                        ; so now we save the contents of BUF into the save slot
                        ;
                        ; Each save slot is split up into three parts, so we now
                        ; need to split the commander file before saving them

 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

 LDA BUF+7              ; Clear bit 7 of the save counter byte in the commander
 AND #%01111111         ; file at BUF so we can increment the save counter once
 STA BUF+7              ; again to record the next save after this one (the save
                        ; counter is in the byte just after the commander name,
                        ; which is seven characters long, so it's at BUF+7)

 LDY #72                ; We work our way through 73 bytes in each saved part,
                        ; so set an index counter in Y

.scom1

 LDA BUF,Y              ; Copy the Y-th byte of the commander file in BUF to the
 STA (SC),Y             ; Y-th byte of the first saved part

IF _NTSC

 EOR #$0F               ; Set the Y-th byte of the third saved part in S(1 0) to
 STA (S),Y              ; the commander file byte with the low nibble flipped

 EOR #$FF               ; Set the Y-th byte of the second saved part in Q(1 0)
 STA (Q),Y              ; to the commander file byte with both nibbles flipped

ELIF _PAL

 ASL A                  ; Set the Y-th byte of the third saved part in S(1 0) to
 ADC #0                 ; the commander file byte, rotated left in-place
 STA (S),Y

 ASL A                  ; Set the Y-th byte of the second saved part in Q(1 0)
 ADC #0                 ; the commander file byte, rotated left in-place
 STA (Q),Y

ENDIF

 DEY                    ; Decrement the byte counter in Y

 BPL scom1              ; Loop back to scom1 until we have split all 73 bytes
                        ; of the commander file into the three separate parts

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

 RTS                    ; Return from the subroutine

 PHA                    ; This instruction is never run, but it would allow this
                        ; part of the subroutine to be called on its own by
                        ; storing the value of A on the stack so we could
                        ; restore it at the end of the subroutine

.scom2

                        ; If we get here then A = 9, so this is the current
                        ; commander on the left of the screen, so we set the
                        ; currently active in-game commander in NAME to the
                        ; commander in BUF

 LDX #78                ; Set a counter in X to copy all 79 bytes of the file

.scom3

 LDA BUF,X              ; Copy the X-th byte of BUF to the X-th byte of the
 STA currentSlot,X      ; current commander in NAME
 STA NAME,X             ;
                        ; This also copies the file to currentSlot, but this
                        ; isn't used anywhere

 DEX                    ; Decrement the byte counter

 BPL scom3              ; Loop back until we have copied all 79 bytes

 JSR SetupAfterLoad_b0  ; Configure the game to use the newly loaded commander
                        ; file

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

 RTS                    ; Return from the subroutine