Following code snippets should give you an inspiration, how an existing assembly based applications like MIDIbox64 or MIDIbox64E can be easily enhanced by additional button functions, which send statically assigned MIDI events.
The idea is to overlay the USER_DIN_NotifyToggle hook. This hook is called by MIOS when a digital input has changed its state (0V→5V or 5V→0V). You can check if a DIN number is within the button range, which should be overlayed. If it is outside the range, then just continue with the application specific code, which handles the remaining buttons - thats all.
Technical details:
The hook is normaly located in the main.asm file of the application.
MIOS forwards following parameters to the hook: MIOS_PARAMETER1: contains the number of the digital input, counted from zero (0..127) MIOS_PARAMETER2: bit #0 is 0, when the digital input is at 0V, and 1, if the digital input is at 5V If buttons are connected, this means: 0V when button closed (pressed), 5V when button open (depressed)
The button range can be checked with the IFLEQ (if-less-equal) and IFGEQ (if-greater-equal) macros, which are defined in macros.h:
;; overlay DIN input #64-#127 (counted from zero) by a simple ;; function which sends dedicated Note Events movlw 64-1 IFLEQ MIOS_PARAMETER1, ACCESS, rgoto USER_DIN_NotifyToggle_NoOverlay movlw 127+1 IFGEQ MIOS_PARAMETER1, ACCESS, rgoto USER_DIN_NotifyToggle_NoOverlay USER_DIN_NotifyToggle_Overlay movlw 0x90 ; Note Event, MIDI Channel #1 call MIOS_MIDI_TxBufferPut movf TMP1, W ; DIN number -> Note Number call MIOS_MIDI_TxBufferPut movlw 0x7f ; Velocity: 0x7f if button pressed IFSET MIOS_PARAMETER2, 0, movlw 0x00 ; 0x00 if button depressed call MIOS_MIDI_TxBufferPut return ; exit USER_DIN_NotifyToggle_NoOverlay ;; ...rest of the application specific code
An interesting variation is following example, which sends different MIDI events depending on a certain button - we could call it “SHIFT” button:
;; overlay DIN input #64-#127 (counted from zero) by a simple ;; function which sends dedicated Note Events movlw 64-1 IFLEQ MIOS_PARAMETER1, ACCESS, rgoto USER_DIN_NotifyToggle_NoOverlay movlw 127+1 IFGEQ MIOS_PARAMETER1, ACCESS, rgoto USER_DIN_NotifyToggle_NoOverlay USER_DIN_NotifyToggle_Overlay ;; since MIOS_DIN_PinGet overwrites MIOS_PARAMETER1, store current button number in TMP1 movff MIOS_PARAMETER1, TMP1 ;; we are using button #8 as shift button (it's outside the range which is overlayed) movlw 8 ; get value of this button (0=pressed, 1=depressed) call MIOS_DIN_PinGet bz USER_DIN_NotifyToggle_Overlay_1 ; branch depending on selection state --- bz == "branch if zero" USER_DIN_NotifyToggle_Overlay_0 movlw 0x90 ; Note Event, MIDI Channel #1 call MIOS_MIDI_TxBufferPut movf TMP1, W ; DIN number -> Note Number call MIOS_MIDI_TxBufferPut movlw 0x7f ; Velocity: 0x7f if button pressed IFSET MIOS_PARAMETER2, 0, movlw 0x00 ; 0x00 if button depressed call MIOS_MIDI_TxBufferPut return ; exit USER_DIN_NotifyToggle_Overlay_1 movlw 0x91 ; Note Event, MIDI Channel #2 call MIOS_MIDI_TxBufferPut movf TMP1, W ; DIN number -> Note Number call MIOS_MIDI_TxBufferPut movlw 0x7f ; Velocity: 0x7f if button pressed IFSET MIOS_PARAMETER2, 0, movlw 0x00 ; 0x00 if button depressed call MIOS_MIDI_TxBufferPut return ; exit USER_DIN_NotifyToggle_NoOverlay ;; ...rest of the application specific code
Please note: if you have ideas for much more complex button functions, but no motivation to learn assembly language, just consider the use of the SDCC wrapper - see also the examples at this Page
Unfortunately it is not possible to combine the assembly based applications like MIDIbox64 or MIDIbox64E with C programs, but maybe your requirements to the application don't match with these historic MIDIboxes anyhow (e.g. you don't need on-screen editing capabilities, you don't need several banks of buttons/encoders/pots/fader setups, you only want to send unique MIDI events to a host ), that it makes sense to program a small C based application instead, and especially to share it with other MIDIbox users!
Additional Hints: