Sound: MakeSoundEnvelope

       Name: MakeSoundEnvelope                                       [Show more]
       Type: Subroutine
   Category: Sound
    Summary: Either make a sound or set up an envelope
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * MakeSound calls MakeSoundEnvelope


 Arguments:

   A                    The action:

                          * A = 7 make a sound

                          * A = 8 to define a sound envelope

   X                    The low byte of the address of the OSWORD block

   xStoreSound          The value of X to restore at the end of the routine


.MakeSoundEnvelope

 LDY #HI(soundData)     \ Set y to the high byte of the soundData block
                        \ address, so (Y X) now points to the relevant envelope
                        \ or sound data block

 JSR OSWORD             \ Call OSWORD with action A, as follows:
                        \
                        \  * A = 7 to make the sound at (Y X)
                        \
                        \  * A = 8 to set up the sound envelope at (Y X)

 LDX xStoreSound        \ Restore the value of X we stored before calling the
                        \ routine, so it doesn't change

 RTS                    \ Return from the subroutine