12.  MIDI



INPMID$


With the command INPMID$ the internal Midi-buffer is read and at the same 
time cleared:

     dummy$=INPMID$                ! clear Midi-buffer


You can find the buffer-address and the buffer-size with XBIOS 14 (Iorec):

     adr%=LPEEK(XBIOS(14,2))
     size%=DPEEK(adr%+4)


The default size of the Midi-buffer is only 128 bytes, but you can change 
the size of the buffer:

     ptr%=XBIOS(14,2)
     DIM buffer|(size%-1)            ! new Midi-buffer
     LPOKE ptr%,VARPTR(buffer|(0))   ! start-address of new buffer
     DPOKE ptr%+4,size%              ! size
     DPOKE ptr%+6,0                  ! buffer-head
     DPOKE ptr%+8,0                  ! buffer-tail
     DPOKE ptr%+10,0                 ! low mark (not used)
     DPOKE ptr%+12,size%-1           ! high mark (not used)

Because handshake is impossible with Midi, you need a large buffer (at 
least 16 K) if Midi-bytes are coming in fast.



INP


If you use INP(3) to read Midi-bytes, you should first check with INP?(3) 
if the Midi-buffer contains data. If you use INP(3) and no bytes are 
available, your ST will freeze. Until you reset the computer.



                        Procedures (CHAPTER.12)


Midi_buffer_new & Midi_buffer_restore (page 12-1)                 MIDI_BUF
Change the size of the Midi-buffer (default 128 bytes):
     @midi_buffer_new(16384,old.buffer%)     ! 16 K
     (...)
     @midi_buffer_restore(old.buffer%)       ! restore default buffer


Midi_monitor                                                      MIDI_MON
A simple Midi-monitor to examine the Midi-bytes that are received by your 
Atari ST:
     @midi_monitor


Midi_off                                                          MIDI_OFF
Switch everything off on one Midi-channel:
     @midi_off(1)        ! switch off on channel 1


Midi_off_all                                                      MIDI_ALL
Switch everything off on all channels (1-16):
     @midi_off_all


Midi_play                                                         MIDIPLAY
Play music that has been recorded with Procedure Midi_record:
     @midi_record(last.byte%,song|(),song.time%())     ! improvise
     @midi_play(last.byte%,song|(),song.time%())       ! listen


Midi_record                                                       MIDIRCRD
Record music. Play it with Procedure Midi_play.


The following Midi-command Procedures have self-evident names. Please note 
that you have to use 1-16 for the Midi-channels and 0-127 for other 
parameters (unless otherwise stated in a Procedure).
                                                                \MIDI_COM\ 
Midi_channel_pressure                                             CH_PRESS
Midi_control                                                       CONTROL
Midi_data                                                             DATA
Midi_hold                                                             HOLD
Midi_key_pressure                                                 KEY_PRES
Midi_modulation                                                   MODULATN
Midi_note_off                                                     NOTE_OFF
Midi_note_on                                                       NOTE_ON
Midi_notes_off                                                    NOTESOFF
Midi_omni                                                             OMNI
Midi_pitch_bend                                                   PITCHBND
Midi_program                                                       PROGRAM
Midi_volume                                                         VOLUME