Save and load: LOD

       Name: LOD                                                     [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Load a commander file
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * SVE calls LOD


 The filename should be stored at INWK, terminated with a carriage return (13).


 Other entry points:

   LOR                  Set the C flag and return from the subroutine


.LOD

 JSR COPYNAME           ; Copy the last saved commander's name from INWK+5 to
                        ; comnam and pad out the rest of comnam with spaces, so
                        ; we can use it as the filename to read in rfile

 JSR rfile              ; Load the commander file into the buffer at comfil

 BCS diskerror          ; If the C flag is set then there was a disk error, so
                        ; jump to diskerror to print the disk error (whose
                        ; number is now in A), make a beep and wait for a key
                        ; press

 JSR UNMUTILATE         ; Decrypt the newly loaded file in the buffer at comfil

 LDA TAP%               ; If the first byte of the loaded file has bit 7 set,
 BMI ELT2F              ; jump to ELT2F, as this is an invalid commander file
                        ;
                        ; ELT2F contains a BRK instruction, which will force an
                        ; interrupt to call the address in BRKV, which will
                        ; print out the system error at ELT2F

 LDY #NT%               ; We have successfully loaded the commander file to the
                        ; TAP% staging area, so now we want to copy it to the
                        ; last saved commander data block at NA%+8, so we set up
                        ; a counter in Y to copy NT% bytes

.copyme

 LDA TAP%,Y             ; Copy the Y-th byte of TAP% to the Y-th byte of NA%+8
 STA NA%+8,Y

 DEY                    ; Decrement the loop counter

 BPL copyme             ; Loop back until we have copied all NT% bytes

.LOR

 SEC                    ; Set the C flag

 RTS                    ; Return from the subroutine

.ELT2F

 LDA #9                 ; Print extended token 9 ("{cr}{all caps}ILLEGAL ELITE
 JSR DETOK              ; II FILE{sentence case}")

 JSR t                  ; Scan the keyboard until a key is pressed, returning
                        ; the ASCII code in A and X

 JMP SVE                ; Jump to SVE to display the disk access menu and return
                        ; from the subroutine using a tail call