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⌂ ∞ Elite on the BBC Micro and NES

Equipment: MoveEquipmentUp

[NES version, Bank 0]

       Name: MoveEquipmentUp                                         [Show more]
       Type: Subroutine
   Category: Equipment
    Summary: Move the currently selected item up the list of equipment

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * EQSHP calls MoveEquipmentUp




.MoveEquipmentUp

 JSR PrintEquipment     ; Print the name and price for the equipment item in
                        ; XX13

 LDA XX13               ; Set A = XX13 - 1, so A contains the item number above
 SEC                    ; the currently selected item in the equipment list
 SBC #1

 BNE equp1              ; If XX13 is non-zero then we have not just tried to
                        ; move off the top of the list, so jump to equp1 to skip
                        ; the following instruction

 LDA #1                 ; Set A = 1 to set the currently selected item to the
                        ; first item in the list, so we don't go past the top
                        ; of the list

.equp1

 STA XX13               ; Store the new item number in XX13, so we move up the
                        ; equipment list

                        ; Fall through into UpdateEquipment to highlight the
                        ; newly chosen item of equipment, update the Cobra Mk
                        ; III, redraw the screen and rejoin the main EQSHP
                        ; routine to continue checking for button presses