DECLARE SUB EchoInit            ' ECHO INITALIZATION
    EchoZ80Reset                ' Reset Z80
    EchoZ80request              ' Request Z80 Bus
    POKE &hA01FFF, 1            ' Write init command number so that this is the first command executed by echo
    reload VoiceList            ' Instrument Pointer List gets loaded
    EchoWriteAdressParam        ' Write the address of the pointer list to Z80 memory
    i=0                         ' i = amount of bytes written
    reload Z80ProgEnd           ' Load the end of the driver binary into Dataptr&()
    a& = dataptr&()             ' Use that as an ending marker for the transfer operation
    reload Z80Prog              ' Load the adress of the Z80 driver
    WHILE dataptr&() < a&       ' (LOOP) Copy the driver into the start of Z80 memory
        READ byt                ' Read next byte of the binary
        POKE 10485760+i, byt    ' Write it to Z80 memory
        i=i+1                   ' increase counter
    WEND                        ' Do this until the full binary is loaded
    EchoZ80Reset                ' Reset Z80
    EchoZ80Release              ' Release Z80 Bus
END SUB

' SUB: ECHOGETSTATUS
'
' Returns the status of Echo (see docs for that)

DECLARE FUNCTION EchoGetStatus AS INTEGER
    EchoZ80Request
    RETURN PEEK(&hA01FF0)
    EchoZ80Release
END FUNCTION

' SUB: ECHOZ80REQUEST
'
' Requests the Z80 Bus

DECLARE SUB EchoZ80Request
    pokeint &hA11100,&h0100     ' Request Z80 Bus
END SUB

' SUB: ECHOZ80RELEASE
'
' Releases the Z80 Bus

DECLARE SUB EchoZ80Release
    pokeint &hA11100,&h0000     ' Release Z80 Bus
END SUB

DECLARE SUB EchoZ80Reset
    pokeint &hA11200,&h0000     ' Assert reset line
    asm                         ' These nops make the 68k wait until the Z80 is operational
        nop                     ; before releasing its RESET LINE
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
    END asm
    pokeint &hA11200,&h0100     ' Release reset line
END SUB

' SUB: ECHOSENDCOMMAND
'
' Sends a command to Echo


DECLARE SUB EchoSendCommand(Command AS INTEGER)
    EchoZ80Request
    WHILE PEEK(&hA01FFF) > 0
        EchoZ80Release ' If Echo is not ready, let it continue for a while
        f = &hFF
        WHILE f > 0
            f--
        WEND
        EchoZ80Request
    WEND
    POKE &hA01FFF, Command
    EchoZ80Release
END SUB

' SUB: ECHOSENDCOMMANDEX
'
' Sends a command with an adress parameter to Echo

DECLARE SUB EchoSendCommandEx(Command AS INTEGER)
    EchoSendCommand Command
    EchoZ80Request
    EchoWriteAdressParam
    EchoZ80Release
END SUB

' SUB: ECHOWRITEADRESSPARAM
'
' Writes an adress parameter for a command into Z80 RAM

DECLARE SUB EchoWriteAdressParam
    regmove.l 0, d1             ' Clear d1 register of the 68K
    ParamAdress& = dataptr&()   ' Get adress from DataPtr&()
    regmove.l ParamAdress&, d0  ' Move the adress into d0 register
    asm                         ' Because this is complicated, we will use assembly for this
        clr.l d1
        move.b  d0, ($A01FFD)
        lsr.l   #7, d0
        lsr.b   #1, d0
        bset.l  #7, d0
        move.b  d0, ($A01FFE)
        lsr.w   #8, d0
        move.w  d0, d1
        lsr.w   #1, d1
        AND.b   #$7F, d0
        AND.b   #$80, d1
        OR.b    d1, d0
        move.b  d0, ($A01FFC)
    END asm
END SUB

' SUB: ECHO COMMANDS
'
' See their comment for information on what they actually do

DECLARE SUB EchoPlayBGM ' Tells Echo to play the BGM
    EchoSendCommandEx 4
END SUB

DECLARE SUB EchoStopBGM ' Tells Echo to stop the BGM
    EchoSendCommand 5
END SUB

DECLARE SUB EchoPlaySFX ' Tells Echo to play the SFX
    EchoSendCommandEx 2
END SUB

DECLARE SUB EchoStopSFX ' Tells Echo to stop the SFX
    EchoSendCommand 3
END SUB