Equipment: refund

       Name: refund                                                  [Show more]
       Type: Subroutine
   Category: Equipment
    Summary: Install a new laser, processing a refund if applicable
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * EQSHP calls refund


 Arguments:

   A                    The power of the new laser to be fitted

   X                    The view number for fitting the new laser (0-3)


 Returns:

   A                    A is preserved

   X                    X is preserved


.refund

 STA T1                 ; Store A in T1 so we can retrieve it later

 LDA LASER,X            ; If there is no laser in view X (i.e. the laser power
 BEQ ref3               ; is zero), jump to ref3 to skip the refund code

 LDY #4                 ; If the current laser has power #POW+9 (pulse laser),
 CMP #POW+9             ; jump to ref1 with Y = 4 (the item number of a pulse
 BEQ ref1               ; laser in the table at PRXS)

 LDY #5                 ; If the current laser has power #POW+128 (beam laser),
 CMP #POW+128           ; jump to ref1 with Y = 5 (the item number of a beam
 BEQ ref1               ; laser in the table at PRXS)

 LDY #12                ; If the current laser has power #Armlas (military
 CMP #Armlas            ; laser), jump to ref1 with Y = 12 (the item number of a
 BEQ ref1               ; military laser in the table at PRXS)

 LDY #13                ; Otherwise this is a mining laser, so fall through into
                        ; ref1 with Y = 13 (the item number of a mining laser in
                        ; the table at PRXS)

.ref1

                        ; We now want to refund the laser of type Y that we are
                        ; exchanging for the new laser

 STX ZZ                 ; Store the view number in ZZ so we can retrieve it
                        ; later

 TYA                    ; Copy the laser type to be refunded from Y to A

 JSR prx                ; Call prx to set (Y X) to the price of equipment item
                        ; number A

 JSR MCASH              ; Call MCASH to add (Y X) to the cash pot

 LDX ZZ                 ; Retrieve the view number from ZZ

.ref3

                        ; Finally, we install the new laser

 LDA T1                 ; Retrieve the new laser's power from T1 into A

 STA LASER,X            ; Set the laser view to the new laser's power

 JSR BEEP_b7            ; Call the BEEP subroutine to make a short, high beep

 JMP EQSHP              ; Jump back to the EQSHP routine (which called this
                        ; routine using a JMP), to redisplay the Equip Ship
                        ; screen

 RTS                    ; Return from the subroutine