DECLARE SUB LoadOPL2Frequency (FMKey AS ANY, OPL2Grid%())
DECLARE SUB LoadOPL2GridIndex (FMKey AS ANY, OPL2Grid%())
DECLARE SUB LoadOPL2WaveEffect (FMKey AS ANY, Effect AS ANY, OPL2Grid%())
DECLARE SUB LoadOPL2WaveEnvelope (FMKey AS ANY, Envelope AS ANY, OPL2Grid%())
DECLARE SUB MonoLoadOPL2 (FMKey AS ANY, MonoGrid%())
DECLARE SUB SetOPL2InstrumentVolume (FMKey AS ANY, OPL2Grid%())
DEFINT A-Z

TYPE OPL2

  MonoStatusPort AS INTEGER
  MonoDataPort AS INTEGER
  LeftStatusPort AS INTEGER
  LeftDataPort AS INTEGER
  RightStatusPort AS INTEGER
  RightDataPort AS INTEGER

  Status AS INTEGER
  TimerStatusBit1 AS INTEGER
  TimerFlag1 AS INTEGER
  TimerStatusBit2 AS INTEGER
  TimerFlag2 AS INTEGER
  InterruptBit AS INTEGER
  InterruptFlag AS INTEGER

  TimerResolution1 AS INTEGER
  TimerResolution2 AS INTEGER

  ActiveRegister AS INTEGER
  RegisterControl AS INTEGER
  ActiveChannel AS INTEGER
  ActiveOperator AS INTEGER
  IncomingMonoData AS INTEGER
  IncomingLeftData AS INTEGER
  IncomingRightData AS INTEGER
  IncomingData AS INTEGER
  OPL2PresentFlag AS INTEGER

  StatusWriteDelay AS INTEGER
  DataWriteDelay AS INTEGER
  DelayCountdown AS INTEGER

  MonoGridOffset AS INTEGER
  MonoGridLimit AS INTEGER
  StereoGridOffset AS INTEGER
  StereoGridLimit AS INTEGER

  WaveControl AS INTEGER
  Wave AS INTEGER
  TimerDataControl1 AS INTEGER
  TimerPreset1 AS INTEGER
  TimerDataControl2 AS INTEGER
  TimerPreset2 AS INTEGER
  TimerControl AS INTEGER
  TimerState AS INTEGER
  IRQResetBit AS INTEGER
  IRQResetFlag AS INTEGER
  TimerMaskBit1 AS INTEGER
  TimerMaskFlag1 AS INTEGER
  TimerMaskBit2 AS INTEGER
  TimerMaskFlag2 AS INTEGER
  TimerActiveBit1 AS INTEGER
  TimerActiveFlag1 AS INTEGER
  TimerActiveBit2 AS INTEGER
  TimerActiveFlag2 AS INTEGER
  SpeechSynthControl AS INTEGER
  SpeechSynthBit AS INTEGER
  SpeechSynthFlag AS INTEGER
  SpeechSynth AS INTEGER
  KeyboardSplitControl AS INTEGER
  KeyboardSplitBit AS INTEGER
  KeyboardSplitFlag AS INTEGER
  KeyboardSplit AS INTEGER

  FMControl AS INTEGER
  FMLimit AS INTEGER
  AmplitudeBit AS INTEGER
  AmplitudeFlag AS INTEGER
  Amplitude AS INTEGER
  VibratoBit AS INTEGER
  VibratoFlag AS INTEGER
  Vibrato AS INTEGER
  EGBit AS INTEGER
  EGFlag AS INTEGER
  EG AS INTEGER
  KeyboardScaleBit AS INTEGER
  KeyboardScaleFlag AS INTEGER
  KeyboardScale AS INTEGER
  FMMultipleBit AS INTEGER
  FMMultiple AS INTEGER

  VolumeControl AS INTEGER
  VolumeLimit AS INTEGER
  KeyScaleLevelBit AS INTEGER
  KeyScaleLevel AS INTEGER
  VolumeBit AS INTEGER
  Volume AS INTEGER

  AttackControl AS INTEGER
  AttackLimit AS INTEGER
  AttackBit AS INTEGER
  Attack AS INTEGER
  DecayBit AS INTEGER
  Decay AS INTEGER

  SustainControl AS INTEGER
  SustainLimit AS INTEGER
  SustainBit AS INTEGER
  Sustain AS INTEGER
  ReleaseBit AS INTEGER
  Release AS INTEGER

  FrequencyControl AS INTEGER
  FrequencyLimit AS INTEGER
  Frequency AS INTEGER
  NoteCSharp AS INTEGER
  NoteD AS INTEGER
  NoteDSharp AS INTEGER
  NoteE AS INTEGER
  NoteF AS INTEGER
  NoteFSharp AS INTEGER
  NoteG AS INTEGER
  NoteGSharp AS INTEGER
  NoteA AS INTEGER
  NoteASharp AS INTEGER
  NoteB AS INTEGER
  NoteC AS INTEGER

  OctaveControl AS INTEGER
  OctaveLimit AS INTEGER
  OctaveBit AS INTEGER
  Octave AS INTEGER
  ChannelActiveBit AS INTEGER
  ChannelActiveFlag AS INTEGER
  FrequencyHighBit AS INTEGER

  AMDepthControl AS INTEGER
  AMDepthBit AS INTEGER
  AMDepthFlag AS INTEGER
  VibratoDepthControl AS INTEGER
  VibratoDepthBit AS INTEGER
  VibratoDepthFlag AS INTEGER
  RhythmControl AS INTEGER
  RhythmBit AS INTEGER
  RhythmFlag AS INTEGER
  BassDrumBit AS INTEGER
  BassDrumFlag AS INTEGER
  SnareDrumBit AS INTEGER
  SnareDrumFlag AS INTEGER
  TomTomBit AS INTEGER
  TomTomFlag AS INTEGER
  TopCymbalBit AS INTEGER
  TopCymbalFlag AS INTEGER
  HiHatBit AS INTEGER
  HiHatFlag AS INTEGER

  FeedbackControl AS INTEGER
  FeedbackLimit AS INTEGER
  FeedbackBit AS INTEGER
  Feedback AS INTEGER
  SynthAlgorithmBit AS INTEGER
  SynthAlgorithmFlag AS INTEGER

  WaveSelectControl AS INTEGER
  WaveSelectLimit AS INTEGER
  WaveSelect AS INTEGER
  SineBit AS INTEGER
  HalfSineBit AS INTEGER
  AbsoluteSineBit AS INTEGER
  PulseSineBit AS INTEGER

  ControlLimit AS INTEGER
  MonoControlLimit AS INTEGER
  StereoControlLimit AS INTEGER
END TYPE

DIM OPL2Key AS OPL2

OPL2Key.MonoStatusPort = &H388
OPL2Key.MonoDataPort = &H389
OPL2Key.LeftStatusPort = &H220
OPL2Key.LeftDataPort = &H222
OPL2Key.RightStatusPort = &H221
OPL2Key.RightDataPort = &H223

OPL2Key.TimerStatusBit1 = 64
OPL2Key.TimerStatusBit2 = 32
OPL2Key.InterruptBit = 128

OPL2Key.StatusWriteDelay = 6
OPL2Key.DataWriteDelay = 35

OPL2Key.WaveControl = &H1
OPL2Key.TimerDataControl1 = &H2
OPL2Key.TimerDataControl2 = &H3
OPL2Key.TimerControl = &H4
OPL2Key.IRQResetBit = 128
OPL2Key.TimerMaskBit1 = 64
OPL2Key.TimerMaskBit2 = 32
OPL2Key.TimerActiveBit1 = 1
OPL2Key.TimerActiveBit2 = 2
OPL2Key.SpeechSynthControl = &H8
OPL2Key.SpeechSynthBit = 128
OPL2Key.KeyboardSplitControl = &H8
OPL2Key.KeyboardSplitBit = 64

OPL2Key.FMControl = &H20
OPL2Key.FMLimit = &H35
OPL2Key.AmplitudeBit = 128
OPL2Key.VibratoBit = 64
OPL2Key.EGBit = 32
OPL2Key.KeyboardScaleBit = 16
OPL2Key.FMMultipleBit = 1

OPL2Key.VolumeControl = &H40
OPL2Key.VolumeLimit = &H55
OPL2Key.KeyScaleLevelBit = 64
OPL2Key.VolumeBit = 1

OPL2Key.AttackControl = &H60
OPL2Key.AttackLimit = &H75
OPL2Key.AttackBit = 16

OPL2Key.SustainControl = &H80
OPL2Key.SustainLimit = &H95
OPL2Key.SustainBit = 1

OPL2Key.FrequencyControl = &HA0
OPL2Key.FrequencyLimit = &HA8

OPL2Key.NoteCSharp = &H16B
OPL2Key.NoteD = &H181
OPL2Key.NoteDSharp = &H198
OPL2Key.NoteE = &H1B0
OPL2Key.NoteF = &H1CA
OPL2Key.NoteFSharp = &H1E5
OPL2Key.NoteG = &H202
OPL2Key.NoteGSharp = &H220
OPL2Key.NoteA = &H241
OPL2Key.NoteASharp = &H263
OPL2Key.NoteB = &H287
OPL2Key.NoteC = &H2AE

OPL2Key.OctaveControl = &HB0
OPL2Key.OctaveLimit = &HB8
OPL2Key.ChannelActiveBit = 32
OPL2Key.OctaveBit = 4
OPL2Key.FrequencyHighBit = 1

OPL2Key.AMDepthControl = &HBD
OPL2Key.AMDepthBit = 128
OPL2Key.VibratoDepthControl = &HBD
OPL2Key.VibratoDepthBit = 64
 
OPL2Key.RhythmControl = &HBD
OPL2Key.RhythmBit = 32
OPL2Key.BassDrumBit = 16
OPL2Key.SnareDrumBit = 8
OPL2Key.TomTomBit = 4
OPL2Key.TopCymbalBit = 2
OPL2Key.HiHatBit = 1

OPL2Key.FeedbackControl = &HC0
OPL2Key.FeedbackLimit = &HC8
OPL2Key.FeedbackBit = 2
OPL2Key.SynthAlgorithmBit = 1

OPL2Key.WaveSelectControl = &HE0
OPL2Key.WaveSelectLimit = &HF5

OPL2Key.ControlLimit = &HF5

DIM MonoControlGrid%(OPL2Key.MonoControlLimit)
DIM StereoControlGrid%(OPL2Key.StereoControlLimit)


TYPE OPL2Patch

  Op1AmplitudeFlag AS INTEGER
  Op2AmplitudeFlag AS INTEGER

  Op1VibratoFlag AS INTEGER
  Op2VibratoFlag AS INTEGER

  Op1EGFlag AS INTEGER
  Op2EGFlag AS INTEGER

  Op1KeyboardScaleFlag AS INTEGER
  Op2KeyboardScaleFlag AS INTEGER

  Op1FMMultiple AS INTEGER
  Op2FMMultiple AS INTEGER

  Op1WaveSelect AS INTEGER
  Op2WaveSelect AS INTEGER

  Op1Attack AS INTEGER
  Op2Attack AS INTEGER

  Op1Decay AS INTEGER
  Op2Decay AS INTEGER

  Op1Sustain AS INTEGER
  Op2Sustain AS INTEGER

  Op1Release AS INTEGER
  Op2Release AS INTEGER
END TYPE

TYPE OPL2Operator

  Index AS INTEGER

  AmplitudeFlag AS INTEGER
  VibratoFlag AS INTEGER
  EGFlag AS INTEGER
  KeyboardScaleFlag AS INTEGER
  FMMultiple AS INTEGER
  WaveSelect AS INTEGER

  Attack AS INTEGER
  Decay AS INTEGER
  Sustain AS INTEGER
  Release AS INTEGER
END TYPE

TYPE OPL2Effect

  AmplitudeFlag AS INTEGER
  VibratoFlag AS INTEGER
  EGFlag AS INTEGER
  KeyboardScaleFlag AS INTEGER
  FMMultiple AS INTEGER
  WaveSelect AS INTEGER
END TYPE

TYPE OPL2Envelope

  Attack AS INTEGER
  Decay AS INTEGER
  Sustain AS INTEGER
  Release AS INTEGER
END TYPE

TYPE Music

  Tempo AS INTEGER
  Note32Duration AS INTEGER

  VolumeStaff AS INTEGER
  VolumeStaffLimit AS INTEGER
  VolumeBarIndex AS INTEGER
  VolumeBarLimit AS INTEGER

  IncomingFrequency AS INTEGER
  Frequency AS INTEGER
  FrequencyStaffLimit AS INTEGER
  FrequencyBarIndex AS INTEGER
  FrequencyBarLimit AS INTEGER
  FrequencyHalf1 AS INTEGER
  FrequencyHalf2 AS INTEGER
  FrequencyAuxillaryFlag AS INTEGER

  IncomingNote AS INTEGER
  Octave AS INTEGER
  Note AS INTEGER

  SongLimit AS INTEGER
  StaffLimit AS INTEGER
  BarIndex AS INTEGER
  BarLimit AS INTEGER
  NoteLimit AS INTEGER
END TYPE

DEFSNG A-Z
SUB DetectOPL2 (FMKey AS OPL2)

  OUT FMKey.TimerControl, &H60
  OUT FMKey.TimerControl, &H80

  OPL2TestControl1% = INP(FMKey.MonoStatusPort)

  OUT FMKey.TimerDataControl1, &HFF
  OUT FMKey.TimerControl, &H21

  FOR FMCounter = 1 TO FMKey.DataWriteDelay
    FMKey.DelayCountdown = INP(FMKey.MonoStatusPort)
  NEXT

  OPL2TestControl2% = INP(FMKey.MonoStatusPort)

  OUT FMKey.TimerControl, &H60
  OUT FMKey.TimerControl, &H80

  OPL2TestControl1% = OPL2TestControl1% AND &HE0
  OPL2TestControl2% = OPL2TestControl2% AND &HE0

  IF OPL2TestControl1% = 0 THEN
    IF OPL2TestControl2% = &HC0 THEN

      FMKey.OPL2PresentFlag = 1
    END IF
  END IF

END SUB

SUB LoadOPL2Frequency (FMKey AS OPL2, OPL2Grid%())

  FMKey.RegisterControl = FMKey.FrequencyControl + FMKey.ActiveChannel
  OPL2Grid%(FMKey.RegisterControl) = FMKey.Frequency AND 256

  FMKey.RegisterControl = FMKey.OctaveControl

  FMKey.IncomingData = FMKey.ChannelActiveBit * FMKey.ChannelActiveFlag
  FMKey.IncomingData = FMKey.IncomingData + (FMKey.OctaveBit * FMKey.Octave)
  FMKey.IncomingData = FMKey.FrequencyHighBit * INT(FMKey.Frequency / 256)

  FMKey.ActiveOperator = 1

  LoadOPL2GridIndex FMKey, OPL2Grid%()

END SUB

DEFINT A-Z
SUB LoadOPL2GridIndex (FMKey AS OPL2, OPL2Grid%())

  GridIndex% = 3 * INT(FMKey.ActiveChannel / 3)
  GridIndex% = GridIndex% + (FMKey.ActiveOperator - 1) * 3
  GridIndex% = GridIndex% + FMKey.RegisterControl + FMKey.ActiveChannel
  OPL2Grid%(GridIndex%) = FMKey.IncomingData

END SUB

SUB LoadOPL2MonoRegister (FMKey AS OPL2)

  OUT FMKey.MonoStatusPort, FMKey.ActiveRegister
  
  FOR FMCounter = 1 TO FMKey.StatusWriteDelay
    FMKey.DelayCountdown = INP(FMKey.MonoStatusPort)
  NEXT

  OUT FMKey.MonoDataPort, FMKey.IncomingMonoData
  
  FOR FMCounter = 1 TO FMKey.DataWriteDelay
    FMKey.DelayCountdown = INP(FMKey.MonoStatusPort)
  NEXT

END SUB

DEFSNG A-Z
SUB LoadOPL2Operator (Operator AS OPL2Operator, FMKey AS OPL2, OPL2Grid%())

  FMKey.ActiveOperator = Operator.Index

  FMKey.RegisterControl = FMKey.FMControl

  FMKey.Amplitude = FMKey.AmplitudeBit * Operator.AmplitudeFlag
  FMKey.AmplitudeFlag = Operator.AmplitudeFlag
  FMKey.IncomingData = FMKey.Amplitude

  FMKey.Vibrato = FMKey.VibratoBit * Operator.VibratoFlag
  FMKey.VibratoFlag = Operator.VibratoFlag
  FMKey.IncomingData = FMKey.IncomingData + FMKey.Vibrato

  FMKey.EG = FMKey.EGBit * Operator.EGFlag
  FMKey.EGFlag = Operator.EGFlag
  FMKey.IncomingData = FMKey.IncomingData + FMKey.EGBit

  FMKey.KeyboardScale = FMKey.KeyboardScaleBit * Operator.KeyboardScaleFlag
  FMKey.KeyboardScaleFlag = Operator.KeyboardScaleFlag
  FMKey.IncomingData = FMKey.IncomingData + FMKey.KeyboardScale

  FMKey.FMMultiple = Operator.FMMultiple
  FMKey.IncomingData = FMKey.IncomingData + FMKey.FMMultiple

  LoadOPL2GridIndex FMKey, OPL2Grid%()

  FMKey.RegisterControl = FMKey.WaveSelectControl
  FMKey.WaveSelect = Operator.WaveSelect

  FMKey.IncomingData = FMKey.WaveSelect
  LoadOPL2GridIndex FMKey, OPL2Grid%()


  FMKey.RegisterControl = FMKey.AttackControl
  FMKey.Attack = Operator.Attack
  FMKey.Decay = Operator.Decay

  FMKey.IncomingData = FMKey.AttackBit * FMKey.Attack
  FMKey.IncomingData = FMKey.IncomingData + FMKey.Decay
  LoadOPL2GridIndex FMKey, OPL2Grid%()

  FMKey.RegisterControl = FMKey.SustainControl
  FMKey.Sustain = Operator.Sustain
  FMKey.Release = Operator.Release

  FMKey.IncomingData = FMKey.SustainBit * FMKey.Sustain
  FMKey.IncomingData = FMKey.IncomingData + FMKey.Release
  LoadOPL2GridIndex FMKey, OPL2Grid%()

END SUB

DEFINT A-Z
SUB LoadOPL2StereoRegister (FMKey AS OPL2)

  OUT FMKey.LeftStatusPort, FMKey.ActiveRegister
 
  FOR FMCounter = 1 TO FMKey.StatusWriteDelay
    FMKey.DelayCountdown = INP(FMKey.LeftStatusPort)
  NEXT

  OUT FMKey.LeftDataPort, FMKey.IncomingLeftData
 
  FOR FMCounter = 1 TO FMKey.DataWriteDelay
    FMKey.DelayCountdown = INP(FMKey.LeftStatusPort)
  NEXT

  OUT FMKey.RightStatusPort, FMKey.ActiveRegister
 
  FOR FMCounter = 1 TO FMKey.StatusWriteDelay
    FMKey.DelayCountdown = INP(FMKey.RightStatusPort)
  NEXT

  OUT FMKey.RightDataPort, FMKey.IncomingRightData
 
  FOR FMCounter = 1 TO FMKey.DataWriteDelay
    FMKey.DelayCountdown = INP(FMKey.RightStatusPort)
  NEXT

END SUB

DEFSNG A-Z
SUB LoadOPL2WaveEffect (FMKey AS OPL2, Effect AS OPL2Effect, OPL2Grid%())

  FMKey.RegisterControl = FMKey.FMControl

  FMKey.Amplitude = FMKey.AmplitudeBit * Effect.AmplitudeFlag
  FMKey.AmplitudeFlag = Effect.AmplitudeFlag
  FMKey.IncomingData = FMKey.Amplitude

  FMKey.Vibrato = FMKey.VibratoBit * Effect.VibratoFlag
  FMKey.VibratoFlag = Effect.VibratoFlag
  FMKey.IncomingData = FMKey.IncomingData + FMKey.Vibrato

  FMKey.EG = FMKey.EGBit * Effect.EGFlag
  FMKey.EGFlag = Effect.EGFlag
  FMKey.IncomingData = FMKey.IncomingData + FMKey.EGBit

  FMKey.KeyboardScale = FMKey.KeyboardScaleBit * Effect.KeyboardScaleFlag
  FMKey.KeyboardScaleFlag = Effect.KeyboardScaleFlag
  FMKey.IncomingData = FMKey.IncomingData + FMKey.KeyboardScale

  FMKey.FMMultiple = Effect.FMMultiple
  FMKey.IncomingData = FMKey.IncomingData + FMKey.FMMultiple

  LoadOPL2GridIndex FMKey, OPL2Grid%()

  FMKey.RegisterControl = FMKey.WaveSelectControl
  FMKey.WaveSelect = Effect.WaveSelect

  FMKey.IncomingData = FMKey.WaveSelect
  LoadOPL2GridIndex FMKey, OPL2Grid%()

END SUB

SUB LoadOPL2WaveEnvelope (FMKey AS OPL2, Envelope AS OPL2Envelope, OPL2Grid%())

  FMKey.RegisterControl = FMKey.AttackControl
  FMKey.Attack = Envelope.Attack
  FMKey.Decay = Envelope.Decay

  FMKey.IncomingData = FMKey.AttackBit * FMKey.Attack
  FMKey.IncomingData = FMKey.IncomingData + FMKey.Decay
  LoadOPL2GridIndex FMKey, OPL2Grid%()

  FMKey.RegisterControl = FMKey.SustainControl
  FMKey.Sustain = Envelope.Sustain
  FMKey.Release = Envelope.Release

  FMKey.IncomingData = FMKey.SustainBit * FMKey.Sustain
  FMKey.IncomingData = FMKey.IncomingData + FMKey.Release
  LoadOPL2GridIndex FMKey, OPL2Grid%()

END SUB

DEFINT A-Z
SUB MonoLoadOPL2 (FMKey AS OPL2, MonoGrid%())

  FOR GridIndex% = FMKey.MonoGridOffset TO FMKey.MonoGridLimit

    FMKey.ActiveRegister = GridIndex%

    OUT FMKey.MonoStatusPort, FMKey.ActiveRegister
   
    FOR FMCounter = 1 TO FMKey.StatusWriteDelay
      FMKey.DelayCountdown = INP(FMKey.MonoStatusPort)
    NEXT

    FMKey.IncomingMonoData = MonoGrid%(FMKey.ActiveRegister)

    OUT FMKey.MonoDataPort, FMKey.IncomingMonoData
   
    FOR FMCounter = 1 TO FMKey.DataWriteDelay
      FMKey.DelayCountdown = INP(FMKey.MonoStatusPort)
    NEXT
  NEXT

END SUB

SUB OpenOPL2Operator (Op AS OPL2Operator, Effect AS OPL2Effect, Envelope AS OPL2Envelope)

  Op.AmplitudeFlag = Effect.AmplitudeFlag
  Op.VibratoFlag = Effect.VibratoFlag
  Op.EGFlag = Effect.EGFlag
  Op.KeyboardScaleFlag = Effect.KeyboardScaleFlag
  Op.FMMultiple = Effect.FMMultiple
  Op.WaveSelect = Effect.WaveSelect

  Op.Attack = Envelope.Attack
  Op.Decay = Envelope.Decay
  Op.Sustain = Envelope.Sustain
  Op.Release = Envelope.Release

END SUB

DEFSNG A-Z
SUB OpenOPL2Patch (Patch AS OPL2Patch, Op1 AS OPL2Operator, Op2 AS OPL2Operator)

  Patch.Op1AmplitudeFlag = Op1.AmplitudeFlag
  Patch.Op2AmplitudeFlag = Op2.AmplitudeFlag

  Patch.Op1VibratoFlag = Op1.VibratoFlag
  Patch.Op2VibratoFlag = Op2.VibratoFlag

  Patch.Op1EGFlag = Op1.EGFlag
  Patch.Op2EGFlag = Op2.EGFlag

  Patch.Op1KeyboardScaleFlag = Op1.KeyboardScaleFlag
  Patch.Op2KeyboardScaleFlag = Op2.KeyboardScaleFlag

  Patch.Op1FMMultiple = Op1.FMMultiple
  Patch.Op2FMMultiple = Op2.FMMultiple

  Patch.Op1WaveSelect = Op1.WaveSelect
  Patch.Op2WaveSelect = Op2.WaveSelect

  Patch.Op1Attack = Op1.Attack
  Patch.Op2Attack = Op2.Attack

  Patch.Op1Decay = Op1.Decay
  Patch.Op2Decay = Op2.Decay

  Patch.Op1Sustain = Op1.Sustain
  Patch.Op2Sustain = Op2.Sustain

  Patch.Op1Release = Op1.Release
  Patch.Op2Release = Op2.Release

END SUB

DEFINT A-Z
SUB PlayOPLMusicBar (Music AS Music, FMKey AS OPL2, OPL2Grid%(), Score$, Frequency$, Volume$)

  IF FMKey.InterruptFlag = 1 THEN

    IF FMKey.TimerFlag2 = 1 THEN

      IF LEN(Volume$) > 0 THEN

        Music.VolumeBarLimit = Music.VolumeStaff + Music.VolumeBarIndex

        FOR VolumeIndex% = 1 TO Music.VolumeStaffLimit

          FMKey.Volume = ASC(MID$(Volume$, VolumeIndex%, 1))

          FMKey.ActiveChannel = VolumeIndex%

          SetOPL2InstrumentVolume FMKey, OPL2Grid%()
        NEXT
      END IF

      IF LEN(Frequency$) > 0 THEN

        FOR FrequencyIndex% = 1 TO Music.FrequencyStaffLimit

          FrequencyHalfIndex% = Music.FrequencyBarIndex + FrequencyIndex%

          Frequency1$ = MID$(Frequency$, FrequencyHalfIndex%, 1)

          Music.IncomingFrequency = ASC(Frequency1$)

          Music.FrequencyHalf1 = 128 - Music.IncomingFrequency

          FrequencyHalfIndex% = Music.FrequencyBarLimit + FrequencyIndex%
 
          Frequency2$ = MID$(Frequency$, FrequencyHalfIndex%, 1)

          Music.FrequencyHalf2 = ASC(Frequency2$)

          FMKey.Frequency = (Music.FrequencyHalf1 * 32) + Music.FrequencyHalf2

          IF FMKey.TimerFlag1 = 1 THEN

            ScoreSubject$ = MID$(Score$, 1, Music.BarIndex + FrequencyIndex% - 1)
            ScorePredicate$ = MID$(Score$, Music.BarIndex + FrequencyIndex% + 1)

            Score$ = ScoreSubject$
            Score$ = Score$ + Frequency1$
            Score$ = Score$ + ScorePredicate$

            ScoreSubject$ = MID$(Score$, 1, Music.BarIndex + FrequencyBarIndex% - 1)
            ScorePredicate$ = MID$(Score$, Music.BarIndex + FrequencyBarIndex% + 1)

            IF Music.FrequencyAuxillaryFlag = 1 THEN

              Score$ = ScoreSubject$
              Score$ = Score$ + Frequency2$
              Score$ = Score$ + ScorePredicate$
            ELSEIF Music.FrequencyAuxillaryFlag = 0 THEN

              Score$ = ScoreSubject$

              FOR FrequencyStaffIndex% = 1 TO (FrequencyIndex% - 1)

                Score$ = Score$ + CHR$(0)
              NEXT

              Score$ = Score$ + Frequency2$

              FOR FrequencyStaffIndex% = 1 TO (Music.StaffLimit - FrequencyIndex%)

                Score$ = Score$ + CHR$(0)
              NEXT

              Score$ = Score$ + ScorePredicate$
            END IF

            Music.SongLimit = Music.SongLimit + Music.StaffLimit

            Music.FrequencyAuxillaryFlag = 1
          END IF

          FMKey.ActiveChannel = FrequencyIndex%

          LoadOPL2Frequency FMKey, OPL2Grid%()
        NEXT

        Music.FrequencyAuxillaryFlag = 0
      END IF
    END IF

    IF FMKey.TimerFlag1 = 1 THEN

      Music.BarLimit = Music.StaffLimit + Music.BarIndex

      IF Music.SongLimit > Music.BarLimit THEN

        Music.NoteLimit = Music.SongLimit - Music.BarLimit
        Bar$ = MID$(Score$, Music.BarIndex, Music.StaffLimit)

        FOR NoteIndex% = 1 TO Music.NoteLimit

          Music.IncomingNote = ASC(MID$(Bar$, NoteIndex%, 1))

          IF Music.IncomingNote > 96 THEN

            Music.FrequencyHalf1 = 128 - Music.IncomingNote

            FrequencyHalfIndex% = Music.BarLimit + NoteIndex%
 
            Frequency$ = MID$(Score$, FrequencyHalfIndex%, 1)

            Music.FrequencyHalf2 = ASC(Frequency$)

            FMKey.Frequency = (Music.FrequencyHalf1 * 32) + Music.FrequencyHalf2
          END IF

          Music.Octave = INT(Music.IncomingNote / 12)

          IF Music.Octave > 8 THEN

            Music.Octave = 0
          END IF

          Music.Note = Music.IncomingNote - (Music.Octave * 12)

          IF Music.Note < 7 THEN

            IF Music.Note < 3 THEN

              IF Music.Note = 1 THEN

                FMKey.Frequency = FMKey.NoteCSharp
              ELSEIF Music.Note = 2 THEN

                FMKey.Frequency = FMKey.NoteD
              ELSE

                FMKey.Frequency = FMKey.NoteDSharp
              END IF
            ELSE

              IF Music.Note = 3 THEN

                FMKey.Frequency = FMKey.NoteE
              ELSEIF Music.Note = 4 THEN

                FMKey.Frequency = FMKey.NoteF
              ELSE

                FMKey.Frequency = FMKey.NoteFSharp
              END IF
            END IF
          ELSEIF Music.Note <= 12 THEN

            IF Music.Note < 9 THEN

              IF Music.Note = 7 THEN

                FMKey.Frequency = FMKey.NoteG
              ELSEIF Music.Note = 8 THEN

                FMKey.Frequency = FMKey.NoteGSharp
              ELSE

                FMKey.Frequency = FMKey.NoteA
              END IF
            ELSE
              IF Music.Note = 10 THEN

                FMKey.Frequency = FMKey.NoteASharp
              ELSEIF Music.Note = 11 THEN

                FMKey.Frequency = FMKey.NoteB
              ELSE

                FMKey.Frequency = FMKey.NoteC
              END IF
            END IF
          END IF

          FMKey.Octave = Music.Octave

          FMKey.ActiveChannel = NoteIndex%

          LoadOPL2Frequency FMKey, OPL2Grid%()
        NEXT

        Music.BarIndex = Music.BarLimit
        Music.BarIndex = Music.BarIndex + Music.StaffLimit
        Music.BarIndex = Music.BarIndex + Music.FrequencyStaffLimit
      END IF
    END IF

    FMKey.MonoGridOffset = FMKey.FrequencyControl
    FMKey.MonoGridLimit = FMKey.FrequencyLimit

    MonoLoadOPL2 FMKey, OPL2Grid%()
  END IF

END SUB

DEFSNG A-Z
SUB RetreiveOPL2Status (FMKey AS OPL2)

  FMKey.Status = INP(FMKey.MonoStatusPort)

  FMKey.TimerFlag1 = FMKey.TimerStatusBit1 AND FMKey.Status
  FMKey.TimerFlag2 = FMKey.TimerStatusBit2 AND FMKey.Status
  FMKey.InterruptFlag = FMKey.InterruptBit AND FMKey.Status

END SUB

DEFINT A-Z
SUB SetOPL2InstrumentVolume (FMKey AS OPL2, OPL2Grid%())

  FMKey.IncomingData = FMKey.KeyScaleLevel * FMKey.KeyScaleLevelBit
  FMKey.IncomingData = FMKey.IncomingData + (FMKey.VolumeBit * FMKey.Volume)
  FMKey.RegisterControl = FMKey.VolumeControl

  IF FMKey.SynthAlgorithmFlag = 1 THEN

    FMKey.ActiveOperator = 1
    LoadOPL2GridIndex FMKey, OPL2Grid%()
  ELSE

    FMKey.ActiveOperator = 1
    LoadOPL2GridIndex FMKey, OPL2Grid%()
    FMKey.ActiveOperator = 2
    LoadOPL2GridIndex FMKey, OPL2Grid%()
  END IF

END SUB

SUB SetOPL2Tempo (Music AS Music, FMKey AS OPL2)

  Music.Note32Duration = (60 / Music.Tempo) * .125

  FMKey.TimerPreset2 = Music.Note32Duration / FMKey.TimerResolution2

END SUB

SUB StereoLoadOPL2 (FMKey AS OPL2, StereoGrid%())

  FOR GridIndex% = FMKey.StereoGridOffset TO INT(FMKey.StereoGridLimit)

    FMKey.ActiveRegister = GridIndex%

    OUT FMKey.LeftStatusPort, FMKey.ActiveRegister

    FOR FMCounter = 1 TO FMKey.StatusWriteDelay
      FMKey.DelayCountdown = INP(FMKey.LeftStatusPort)
    NEXT

    FMKey.IncomingLeftData = StereoGrid%(GridIndex%)

    OUT FMKey.LeftDataPort, FMKey.IncomingLeftData

    FOR FMCounter = 1 TO FMKey.DataWriteDelay
      FMKey.DelayCountdown = INP(FMKey.LeftStatusPort)
    NEXT

    GridIndex% = GridIndex% + 1
    FMKey.IncomingRightData = StereoGrid%(GridIndex%)

    OUT FMKey.RightStatusPort, FMKey.ActiveRegister

    FOR FMCounter = 1 TO FMKey.StatusWriteDelay
      FMKey.DelayCountdown = INP(FMKey.RightStatusPort)
    NEXT

    OUT FMKey.RightDataPort, FMKey.IncomingRightData

    FOR FMCounter = 1 TO FMKey.DataWriteDelay
      FMKey.DelayCountdown = INP(FMKey.RightStatusPort)
    NEXT
  NEXT

END SUB