Ada Smileys in C++ lib Conversion

[Warren <ve3wwg@gmail.com>]

This week I've been busy porting last year's C++
version of my midi library over to Ada (now that I'm
using AVR-Ada).  As part of that effort, the Ada
compiler has discovered a few errors that were
lurking still in the C++ Arduino code.

In C++ I had defined:

/*
 * MC_CTL_CHG Control values :
 */
#define MC_CTL_ALLS_OFF 0x78 // All sounds off (120)
#define MC_CTL_RESET_C  0x79 // Reset controller
#define MC_CTL_LOCAL_C  0x80 // Local on/off
#define MC_CTL_ALLN_OFF 0x81 // All notes off
#define MC_CTL_OMNI_OFF 0x82 // Omni off request
#define MC_CTL_OMNI_ON  0x83 // Omni on request
#define MC_CTL_MONO_ON  0x84 // Mono on == POLY OFF
#define MC_CTL_MONO_OFF 0x85 // Mono off == POLY ON

But in Ada, when I declared:

    type Control_Type is new Unsigned_8 range 0..127;

and then coded:

    case Control is
        when MC_CTL_ALLS_OFF =>  -- ok
            ...
        when MC_CTL_LOCAL_C => -- oops
            ...

it immediately identified the value MC_CTL_LOCAL_C
(and others) as not fitting into the Control_Type's
valid range. In C++ a glaring error had gone
unnoticed:

#define MC_CTL_ALLS_OFF         0x78    // All sounds off (120)
#define MC_CTL_RESET_C          0x79    // Reset controller
#define MC_CTL_LOCAL_C          0x7A    <==== not 0x80
#define MC_CTL_ALLN_OFF         0x7B    <==== not 0x81..

Non commands in midi should not have had bit 7 set.
So as it was coded, those control messages would
never have been processed in the C++ lib.

I'm always smiling when I convert code from C/C++ to
Ada. In code of any significant size, Ada always
discovers problems that went unnoticed in C/C++.

Warren