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⌂ ∞ ▽ Aviator on the BBC Micro

Sound: MakeSound

       Name: MakeSound                                               [Show more]
       Type: Subroutine
   Category: Sound
    Summary: Make a sound

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * ApplyAerodynamics (Part 2 of 3) calls MakeSound
             * Crash calls MakeSound
             * ExplodeAlien calls MakeSound
             * MainLoop (Part 3 of 15) calls MakeSound
             * MakeEngineSound calls MakeSound
             * ProcessLanding (Part 6 of 7) calls MakeSound
             * ScaleFlightForces calls MakeSound
             * ScorePoints calls MakeSound
             * ToggleEngineSound calls MakeSound




 Arguments:

   A                    The sound number from the soundData table (0 to 7)



.MakeSound

 ASL A                  \ Set A = A * 8
 ASL A                  \
 ASL A                  \ so we can use it as an index into the soundData table,
                        \ which has 8 bytes per entry

 CLC                    \ Set (Y X) = soundData + A
 ADC #LO(soundData)     \
 TAX                    \ starting with the low byte in X

 LDA #7                 \ Set A = 7 for the OSWORD command to make a sound

 BNE MakeSoundEnvelope  \ Jump to MakeSoundEnvelope to set up Y and apply the
                        \ OSWORD command to the (Y X) block, which makes the
                        \ relevant sound (this BNE is effectively a JMP as A is
                        \ never zero)