Save and load: UpdateSaveCount

       Name: UpdateSaveCount                                         [Show more]
       Type: Subroutine
   Category: Save and load
    Summary: Update the save counter for the current commander
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * BuyAndSellCargo calls UpdateSaveCount
             * EQSHP calls UpdateSaveCount
             * TT110 calls UpdateSaveCount


 Returns:

   A                    A is preserved


.UpdateSaveCount

 PHA                    ; Store A on the stack so we can retrieve it below

 LDA SVC                ; If bit 7 of SVC is set, then we have already
 BMI scnt1              ; incremented the save counter for the current
                        ; commander, so jump to scnt1 to skip the following and
                        ; leave SVC alone

 CLC                    ; Set A = A + 1, to increment the save counter
 ADC #1

 CMP #100               ; If A < 100, skip the following instruction
 BCC scnt1

 LDA #0                 ; Set A = 0, so the save counter goes from zero to 100
                        ; and around back to zero again

.scnt1

 ORA #%10000000         ; Set bit 7 of A to flag the save counter as increments,
                        ; so the next call to this routine does nothing

 STA SVC                ; Store the updated save counter in SVC

 PLA                    ; Retrieve the value of A we stored on the stack above

 RTS                    ; Return from the subroutine