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⌂ ∞ ▽ Elite on the 6502

Sound: FlushSpecificSound

[NES version, Bank 7]

       Name: FlushSpecificSound                                      [Show more]
       Type: Subroutine
   Category: Sound
    Summary: Flush the channels used by a specific sound

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




 The sound channels are flushed according to the specific sound's value in the
 soundChannel table:

   * If soundChannel = 0, flush the SQ1 sound channel

   * If soundChannel = 1, flush the SQ2 sound channel

   * If soundChannel = 2, flush the NOISE sound channel

   * If soundChannel = 3, flush the SQ1 and NOISE sound channels

   * If soundChannel = 4, flush the SQ2 and NOISE sound channels



 Arguments:

   Y                    The number of the sound to flush



.FlushSpecificSound

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

 CPX #3                 ; If X < 3 then jump to FlushSoundChannel to flush the
 BCC FlushSoundChannel  ; SQ1, SQ2 or NOISE sound channel, as specified in X,
                        ; returning from the subroutine using a tail call

 BNE FlushSQ2AndNOISE   ; If X <> 3, i.e. X = 4, then jump to FlushSQ2AndNOISE
                        ; to flush sound channels 1 and 2, returning from the
                        ; subroutine using a tail call

                        ; If we get here then we know X = 3, so now we flush the
                        ; SQ1 and NOISE sound channels

 LDX #0                 ; Flush the SQ1 sound channel
 JSR FlushSoundChannel

 LDX #2                 ; Set X = 2 and fall through into FlushSoundChannel to
                        ; flush the NOISE sound channel