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⌂ ∞ ▽ Elite on the BBC Micro and NES

Save and load: QUS1

[Acorn Electron version]

       Name: QUS1                                                    [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Save or load the commander file
  Deep dive: Commander save files

    Context: See this subroutine in context in the source code
 Variations: See code variations for this subroutine in the different versions
 References: This subroutine is called as follows:
             * LOD calls QUS1
             * SVE calls QUS1




 The filename should be stored at INWK, terminated with a carriage return (13).
 The routine should be called with Y set to &C.



 Arguments:

   A                    File operation to be performed. Can be one of the
                        following:

                          * 0 (save file)

                          * &FF (load file)

   Y                    Points to the page number containing the OSFILE block,
                        which must be &C because that's where the pointer to the
                        filename in INWK is stored below (by the STX &0C00
                        instruction)



.QUS1

 LDX #INWK              \ Store a pointer to INWK at the start of the block at
 STX &0A00              \ &0A00, storing #INWK in the low byte because INWK is
                        \ in zero page

 LDX #&FF               \ Set KEYB = &FF to indicate that we are reading from
 STX KEYB               \ the keyboard using an OS command

 INX                    \ Set X = 0

 JSR OSFILE             \ Call OSFILE to do the file operation specified in
                        \ &0A00 (i.e. save or load a file depending on the value
                        \ of A)

 INC KEYB               \ Increment KEYB back to 0 to indicate we are done
                        \ reading the keyboard

 RTS                    \ Return from the subroutine