Save and load: drverr

       Name: drverr                                                  [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Return from the RWTS code with a "Disk I/O error"
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * trytrk calls drverr
             * prterr calls via drver2


 Returns:

   A                    The error number for the Disk I/O error (4)

   C flag               The C flag is set


 Other entry points:

   drver2               Restore the stack pointer and return from the RWTS code
                        with the error number in A and the C flag set to
                        indicate an error


.drverr

 LDA #4                 ; Set A = 4 to return as the error number for the "Disk
                        ; I/O error"

.drver2

 LDX stkptr             ; Restore the value of the stack pointer from when we
 TXS                    ; first ran the RWTS code, to remove any return
                        ; addresses or values from the disk access routines
                        ; and make sure the RTS below returns from the RWTS
                        ; code

 SEC                    ; Set the C flag to denote that an error has occurred

 BCS rttrk4             ; Jump to rttrk4 to return from the RWTS code with the
                        ; error number in A and the error status in the C flag