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⌂ ∞ ▽ Elite on the BBC Micro and NES

Save and load: CATS

[BBC Master version]

       Name: CATS                                                    [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Ask for a disc drive number and print a catalogue of that drive

    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:
             * DELT calls CATS
             * SVE calls CATS




 This routine asks for a disc drive number, and if it is a valid number (0-3)
 it displays a catalogue of the disc in that drive. It also updates the OS
 command at CTLI so that when that command is run, it catalogues the correct
 drive.



 Returns:

   C flag               Clear if a valid drive number was entered (0-3), set
                        otherwise



.CATS

IF _SNG47

 JSR GTDRV              \ Get an ASCII disc drive number from the keyboard in A,
                        \ setting the C flag if an invalid drive number was
                        \ entered

 BCS DELT-1             \ If the C flag is set, then an invalid drive number was
                        \ entered, so return from the subroutine (as DELT-1
                        \ contains an RTS)

 STA CTLI+4             \ Store the drive number in the fifth byte of the
                        \ command string at CTLI, so it overwrites the "1" in
                        \ "CAT 1" with the drive number to catalogue

 STA DTW7               \ Store the drive number in DTW7, so printing extended
                        \ token 4 will show the correct drive number (as token 4
                        \ contains the {drive number} jump code, which calls
                        \ MT16 to print the character in DTW7)

ELIF _COMPACT

 JSR GTDIR              \ Get a directory name from the keyboard and change to
                        \ that directory

ENDIF

 LDA #3                 \ Print extended token 3, which clears the screen and
 JSR DETOK              \ prints the boxed-out title "DRIVE {drive number}
                        \ CATALOGUE"

 LDA #1                 \ Set the CATF flag to 1, so that the TT26 routine will
 STA CATF               \ print out the disc catalogue correctly

 STA XC                 \ Move the text cursor to column 1

IF _SNG47

 JSR getzp              \ Call getzp to store the top part of zero page in the
                        \ the buffer at &3000, as it gets corrupted by the MOS
                        \ during disc access

ELIF _COMPACT

 JSR NMIRELEASE         \ Release the NMI workspace (&00A0 to &00A7) so the MOS
                        \ can use it, and store the top part of zero page in the
                        \ the buffer at &3000, as it gets corrupted by the MOS
                        \ during disc access

ENDIF

 LDX #LO(CTLI)          \ Set (Y X) to point to the OS command at CTLI, which
 LDY #HI(CTLI)          \ contains a dot and the drive number, which is the
                        \ DFS command for cataloguing that drive (*. being short
                        \ for *CAT)

 JSR OSCLI              \ Call OSCLI to execute the OS command at (Y X), which
                        \ catalogues the disc

 JSR getzp              \ Call getzp to restore the top part of zero page from
                        \ the buffer at &3000

 STZ CATF               \ Set the CATF flag to 0, so the TT26 routine reverts to
                        \ standard formatting

 CLC                    \ Clear the C flag

 RTS                    \ Return from the subroutine