Sound: BDRO7

       Name: BDRO7                                                   [Show more]
       Type: Subroutine
   Category: Sound
    Summary: Process music command <#7 ad1 ad2 ad3 sr1 sr2 sr3> to set three
             voices' attack and decay length, sustain volume and release length
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * BDJMPTBH calls BDRO7
             * BDJMPTBL calls BDRO7


.BDRO7

 JSR BDlab19            ; Increment the music data pointer in BDdataptr1(1 0)
                        ; and fetch the next music data byte into A

 STA SID+$5             ; Set SID register $5 to the music data byte we just
                        ; fetched, which sets the attack and decay length for
                        ; voice 1 as follows:
                        ;
                        ;   * Bits 0-3 = decay length
                        ;
                        ;   * Bits 4-7 = attack length

 JSR BDlab19            ; Increment the music data pointer in BDdataptr1(1 0)
                        ; and fetch the next music data byte into A

 STA SID+$C             ; Set SID register $C to the music data byte we just
                        ; fetched, which sets the attack and decay length for
                        ; voice 2 as follows:
                        ;
                        ;   * Bits 0-3 = decay length
                        ;
                        ;   * Bits 4-7 = attack length

 JSR BDlab19            ; Increment the music data pointer in BDdataptr1(1 0)
                        ; and fetch the next music data byte into A

 STA SID+$13            ; Set SID register $12 to the music data byte we just
                        ; fetched, which sets the attack and decay length for
                        ; voice 3 as follows:
                        ;
                        ;   * Bits 0-3 = decay length
                        ;
                        ;   * Bits 4-7 = attack length

 JSR BDlab19            ; Increment the music data pointer in BDdataptr1(1 0)
                        ; and fetch the next music data byte into A

 STA SID+$6             ; Set SID register $6 to the music data byte we just
                        ; fetched, which sets the release length and sustain
                        ; volume for voice 1 as follows:
                        ;
                        ;   * Bits 0-3 = release length
                        ;
                        ;   * Bits 4-7 = sustain volume

 JSR BDlab19            ; Increment the music data pointer in BDdataptr1(1 0)
                        ; and fetch the next music data byte into A

 STA SID+$D             ; Set SID register $D to the music data byte we just
                        ; fetched, which sets the release length and sustain
                        ; volume for voice 2 as follows:
                        ;
                        ;   * Bits 0-3 = release length
                        ;
                        ;   * Bits 4-7 = sustain volume

 JSR BDlab19            ; Increment the music data pointer in BDdataptr1(1 0)
                        ; and fetch the next music data byte into A

 STA SID+$14            ; Set SID register $14 to the music data byte we just
                        ; fetched, which sets the release length and sustain
                        ; volume for voice 4 as follows:
                        ;
                        ;   * Bits 0-3 = release length
                        ;
                        ;   * Bits 4-7 = sustain volume

 JMP BDskip1            ; Jump to BDskip1 to process the next nibble of music
                        ; data