Loader: SetUpGMAFile

       Name: SetUpGMAFile                                            [Show more]
       Type: Subroutine
   Category: Loader
    Summary: Configure the filename parameters to load a specific GMA file
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * LoadGMAFile calls SetUpGMAFile


 Arguments:

   A                    The number of the GMA file to load

                          * For the GMA85 NTSC variant: as an ASCII character

                          * For the GMA86 PAL variant: as an integer


.SetUpGMAFile

IF _GMA86_PAL

 TAX                    ; Copy the number of the GMA file into X

 CLC                    ; Add X to the ASCII for '0' to turn 3, 4 or 5 into
 ADC #'0'               ; ASCII characters "3", "4" or "5"

ENDIF

 STA fileNumber         ; Store the ASCII file number in fileNumber so the
                        ; filename gets set to GMA3, GMA4 or GMA5

IF _GMA86_PAL

 TXA                    ; Set X = X * 2
 ASL A                  ;
 TAX                    ; so we can use X as an index into the trackSector
                        ; table, which has two bytes per entry

 LDA trackSector,X      ; Modify the code at mod1 and mod2 with the track
 STA mod1+1             ; and sector numbers for file X, so the fast loader
 LDA trackSector+1,X    ; knows where to find the file on disk
 STA mod2+1

ENDIF

 LDX #LO(filename)      ; Call SETNAM to set the filename parameters as follows:
 LDY #HI(filename)      ;
 LDA #4                 ;   * A = filename length of 4
 JSR KERNALSETNAM       ;
                        ;   * (Y X) = address of filename
                        ;
                        ; So this sets the filename to "GMA*" where "*" is the
                        ; number passed to the subroutine in A

 RTS                    ; Return from the subroutine