Sound: NOISE

       Name: NOISE                                                   [Show more]
       Type: Subroutine
   Category: Sound
    Summary: Make the sound effect whose number is in Y
  Deep dive: Sound effects in NES Elite
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * BEEP calls NOISE
             * BOOP calls NOISE
             * BuyAndSellCargo calls NOISE
             * ECBLB2 calls NOISE
             * ESCAPE calls NOISE
             * EXNO calls NOISE
             * EXNO2 calls NOISE
             * EXNO3 calls NOISE
             * FRMIS calls NOISE
             * Ghy calls NOISE
             * LAUN calls NOISE
             * Main flight loop (Part 3 of 16) calls NOISE
             * Main flight loop (Part 15 of 16) calls NOISE
             * Main game loop (Part 5 of 6) calls NOISE
             * MakeScoopSound calls NOISE
             * MJP calls NOISE
             * SFRMIS calls NOISE
             * TACTICS (Part 6 of 7) calls NOISE


 Arguments:

   Y                    The number of the sound effect to be made


.NOISE

 LDA DNOIZ              ; If DNOIZ is zero then sound is disabled, so jump to
 BPL RTS8               ; RTS8 to return from the subroutine without making a
                        ; sound

 LDX soundChannel,Y     ; Set X to the channel number for sound effect Y

 CPX #3                 ; If X < 3 then this sound effect uses just the channel
 BCC nois1              ; given in X, so jump to nois1 to make the sound effect
                        ; on that channel alone

                        ; If we get here then X = 3 or 4, so we need to make the
                        ; sound effect on two channels:
                        ;
                        ;   * If X = 3, use sound channels 0 and 2
                        ;
                        ;   * If X = 4, use sound channels 1 and 2

 TYA                    ; Store the sound effect number on the stack, so we can
 PHA                    ; restore it after the call to nois1 below

 DEX                    ; Set X = X - 3, so X is now 0 or 1, which is the number
 DEX                    ; of the first channel we need to make the sound on
 DEX                    ; (i.e. the SQ1 or SQ2 channel)

 JSR nois1              ; Call nois1 to make the sound effect on channel X, so
                        ; that's the SQ1 or SQ2 channel

 PLA                    ; Restore the sound effect number from the stack into Y
 TAY

 LDX #2                 ; Set X = 2 and fall through into nois1 to make the
                        ; sound effect on the NOISE channel, which is the number
                        ; of the second channel we need to make the sound on

.nois1

 LDA effectOnSQ1,X      ; If the status flag for channel X is zero, then there
 BEQ nois2              ; is no sound being made on this channel at the moment,
                        ; so jump to nois2 to make the sound

 LDA soundPriority,Y    ; Otherwise set A to the priority of the sound effect we
                        ; want to make

 CMP channelPriority,X  ; If A is less than the priority of the sound currently
 BCC RTS8               ; being made on channel X, then we mustn't interrupt it
                        ; with our lower-priority sound, so return from the
                        ; subroutine without making the new sound

.nois2

                        ; If we get here then we are cleared to make our new
                        ; sound Y on channel X

 LDA soundPriority,Y    ; Set the priority of the sound on channel X to that of
 STA channelPriority,X  ; our new sound, as we are about to make it

 SETUP_PPU_FOR_ICON_BAR ; If the PPU has started drawing the icon bar, configure
                        ; the PPU to use nametable 0 and pattern table 0

 TYA                    ; Set A to the sound number in Y so we can pass it to
                        ; the StartEffect routine

                        ; Fall through into StartEffect_b7 to start making sound
                        ; effect A on channel X