Skip to navigation

⌂ ∞ Elite on the BBC Micro and NES

Combat demo: SetDemoAutoPlay

[NES version, Bank 5]

       Name: SetDemoAutoPlay                                         [Show more]
       Type: Subroutine
   Category: Combat demo
    Summary: Set up the NMI handler to automatically play the demo using the
             controller key presses in the autoPlayKeys table

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * SetDemoAutoPlay_b5 calls SetDemoAutoPlay




.SetDemoAutoPlay

 LDA #5                 ; Set the icon par pointer to button 5 (which is the
 JSR SetIconBarPointer  ; sixth button of 12, just before the halfway point)

 JSR SetupDemoUniverse  ; Configure the universe for the demo, which includes
                        ; setting the random number seeds to a known value so
                        ; the demo always runs in the same way

 LDX languageIndex      ; Set autoPlayKeys(1 0) to the chosen language's entry
 LDA autoPlayKeys1Lo,X  ; from the (autoPlayKeys1Hi autoPlayKeys1Lo) tables
 STA autoPlayKeys
 LDA autoPlayKeys1Hi,X
 STA autoPlayKeys+1

 LDA #0                 ; Set autoPlayKey = 0 to reset the current key being
 STA autoPlayKey        ; "pressed" in the auto-play

 STA autoPlayRepeat     ; Set autoPlayRepeat = 0 to reset the number of repeats
                        ; in the auto-play (as otherwise the first button press
                        ; would start repeating)

 LDX #%10000000         ; Set bit 7 of autoPlayDemo so the NMI handler will play
 STX autoPlayDemo       ; the demo automatically using the controller key
                        ; presses in the autoPlayKeys tables

 RTS                    ; Return from the subroutine