The BDRO4 subroutine - Elite on the 6502

       Name: BDRO4                                                   [Show more]
       Type: Subroutine
   Category: Sound
    Summary: Process music command <#4 fh1 fl1 fh2 fl2> to set the frequencies
             and voice control registers for voices 1 and 2
  Deep dive: Music in Commodore 64 Elite
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * BDJMPTBH calls BDRO4
             * BDJMPTBL calls BDRO4


.BDRO4

 JSR BDlab3             ; Fetch the next two music data bytes and set the
                        ; frequency of voice 1 (high byte then low byte)

 JSR BDlab5             ; Fetch the next two music data bytes and set the
                        ; frequency of voice 2 (high byte then low byte) and the
                        ; vibrato variables for voice 2

 JSR BDlab4             ; Set the voice control register for voice 1 to value1

 JSR BDlab6             ; Set the voice control register for voice 2 to value2

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

[X]

Subroutine BDlab3 (category: Sound)

Fetch the next two music data bytes and set the frequency of voice 1 (high byte then low byte)

[X]

Subroutine BDlab4 (category: Sound)

Set the voice control register for voice 1 to value1

[X]

Subroutine BDlab5 (category: Sound)

Fetch the next two music data bytes and set the frequency of voice 2 (high byte then low byte) and the vibrato variables

[X]

Subroutine BDlab6 (category: Sound)

Set the voice control register for voice 2 to value2

[X]

Entry point BDskip1 in subroutine BDirqhere (category: Sound)

Process the next nibble of music data in BDBUFF

Sound: BDRO4

[Commodore 64 version]