'****************************************************************************
' INITMIDI.BAS                                                
' MPU-401 Hardware Handshaking routines based on routines by Michel Poirier,
' MIDICOM Montreal Fido 167/111, (514) 744-7354                          
' Posted to comp.lang.basic.misc by Wayne Freno, wfreno@vcn.bc.ca June 7/97
' Please send any bug fixes or any interesting algorithms to wfreno@vcn.bc.ca
'****************************************************************************
' First call InitMidi to initialize the MPU
' ReadData is used to read bytes from the computer's MIDI in.  Use PRINT to
' see what they are.
' Play1note is there to demonstrate output.
' AllNotesOff should be called at the end, just before ResetMidi.
'
DECLARE SUB ResetMidi (dataport, Rst, DRR)
DECLARE SUB AllNotesOff (dataport)
DECLARE SUB InitMidi (dataport, comport, Rst, DRR, Uart)
DECLARE SUB ReadData (dataport, comport, DSR)
DECLARE SUB Play1note (dataport, comport, DRR, ch0, notes, rests, velo, dur)

dataport = &H330                ' Port where MIDI bytes are sent
comport = &H331                 ' Port where commands are sent
DSR = &H80                      ' Data Set Ready. Used for incoming bytes
DRR = &H40                      ' Data Read Ready. Used for outgoing bytes
Uart = &H3F                     ' Used to put MPU into dumb mode
Ack = &HFE                      ' Acknowledge byte sent to data port
Rst = &HFF                      ' Reset MPU

CALL InitMidi(dataport, comport, Rst, DRR, Uart)

CLS

' sample output
DO
    notes = INT(RND * 30) + 50              ' notes to send
    rests = INT(RND * 2) - 1
    CALL Play1note(dataport, comport, DRR, 0, notes, rests, 99, 1600)

LOOP WHILE INKEY$ = ""

CALL AllNotesOff(dataport)
CALL ResetMidi(dataport, Rst, DRR)

END

SUB AllNotesOff (dataport)

FOR c = 0 TO 15     ' step through the MIDI channels

    WHILE (INP(comport) AND DRR = DRR)  ' make sure its ok to send data
        purge = INP(dataport)
    WEND
    OUT dataport, &HB0 + c          ' Control change status byte, plus channel
    purge = INP(dataport)           ' Read Acknowledge

    WHILE (INP(comport) AND DRR = DRR)
        purge = INP(dataport)        ' Read Acknowledge byte to clear the port
    WEND
    OUT dataport, 123                ' Controller #123 All Notes Off
    purge = INP(dataport)

    WHILE (INP(comport) AND DRR = DRR)
        purge = INP(dataport)
    WEND
    OUT dataport, 127                ' 0 to 63 = off, 64 to 127 = on
    purge = INP(dataport)
NEXT c

END SUB

SUB InitMidi (dataport, comport, Rst, DRR, Uart)
   
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND
    OUT comport, Rst                ' Reset sent to command port
    purge = INP(dataport)

   
   
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND
    OUT comport, Uart               ' Put the MPU in Uart (dumb) mode
    purge = INP(dataport)

END SUB

SUB Play1note (dataport, comport, DRR, ch0, notes, rests, velo, dur)
   
    IF rests = 0 THEN
        velo = 0
    ELSE
        velo = velo
    END IF
   
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND
  
    OUT dataport, &H90 + ch0               ' NOTE ON channel 0
    purge = INP(dataport)
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND

    OUT dataport, notes                     ' notes to play
    purge = INP(dataport)
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND

    OUT dataport, velo                      ' note velocity
    purge = INP(dataport)
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND

    OUT dataport, &H90 + ch0               ' NOTE OFF Channel 0
    purge = INP(dataport)
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND

    OUT dataport, notes                     ' notes to turn off
    purge = INP(dataport)
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND

    OUT dataport, 0                     ' velocity 0, same as note off
    purge = INP(dataport)
    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND

    FOR d = 1 TO dur: NEXT d                ' how long between notes

END SUB

SUB ReadData (dataport, comport, DSR)
SHARED Byte

    WHILE (INP(comport) AND DSR) = DSR: WEND

    Byte = INP(dataport)

END SUB

SUB ResetMidi (dataport, Rst, DRR)
' put sub at end of program

    WHILE (INP(comport) AND DRR) = DRR
        purge = INP(dataport)
    WEND
    OUT comport, Rst                ' Reset MPU to its default state
    purge = INP(dataport)

END SUB