Hi stevieb. Another way is prefixing the functions considered private with an underscore.

 _ads1115Setup
 _analogRead
 _analogWrite
 _bmp180Pressure
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Thanks marioroy, I've considered that, but that would require some structural changes to the XS (however, I'm not overly against doing so).

Currently, I have my XSUBs loaded as they are direct from the C libraries themselves, when I don't need to wrap them again locally:

void digitalWriteByte(value)
    int value

void digitalWriteByte2(value)
    int value

# SPI

int wiringPiSPISetup(channel, speed)
    int channel
    int speed
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Other ones have full-blown C wrappers as stated, then the XSUB calls the actual function:

Wrapper:

void spiDataRW(int channel, SV* byte_ref, int len){

     /*
      * Custom wrapper for wiringPiSPIDataRW() as we
      * need to translate an aref into an unsigned char *,
      * and then send back an array containing the bytes
      * read from the device
      */ 

    if (channel != 0 && channel != 1){
        croak("channel param must be 0 or 1\n");
    }

    if (! SvROK(byte_ref) || SvTYPE(SvRV(byte_ref)) != SVt_PVAV){
        croak("data param must be an array reference\n");
    }

    AV* bytes = (AV*)SvRV(byte_ref);

    int num_bytes = av_len(bytes) + 1;

    if (len != num_bytes){
        croak("len param doesn't match element count in data\n");
    }

    unsigned char buf[num_bytes];

    int i;

    for (i=0; i<len; i++){
        SV** elem = av_fetch(bytes, i, 0);

        int elem_int = (int)SvNV(*elem);
        
        if (elem_int < 0 || elem_int > 255){
            printf("byte %d in data param out of range: (%d)\n", i, el
+em_int);
            exit(1);
        }

        buf[i] = (unsigned char)SvNV(*elem);
    }
    
    if (wiringPiSPIDataRW(channel, buf, len) < 0){
        croak("failed to write to the SPI bus\n");
    }

    inline_stack_vars;
    inline_stack_reset;

    int x;
    for (x=0; x<len; x++){
        inline_stack_push(sv_2mortal(newSViv(buf[x])));
    } 

    inline_stack_done;
}
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The wrapper in XS then calls the C function I'm wrapping with the manipulated arguments:

void spiDataRW (channel, byte_ref, len)
    int    channel
    SV *    byte_ref
    int    len
        PREINIT:
        I32* temp;
        PPCODE:
        temp = PL_markstack_ptr++;
        spiDataRW(channel, byte_ref, len);
        if (PL_markstack_ptr != temp) {
          PL_markstack_ptr = temp;
          XSRETURN_EMPTY;
        }
        return;
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I've been 'learning' for a full year at this stuff amongst other things, but I'm no where near proficient. I have learned about using the PREFIX directive in my XS code, and that'll likely help.

What I think is that preceeding everything with the Perl private notation may not work here very easily as there is a lot going on. I will play though. I've got everything exceptionally stable, all tests pass against everything, so I'm relatively content.

I'm going to leave well enough alone for the time being, and poke my CI test software for a bit, to fix some issues there. This task can wait; I just thought another question wouldn't hurt here ;)

Cheers,

-stevieb

ps. In the example given where I do trickery turning a perl aref into a char pointer, I know thanks to the Monks how to do that stuff with pack etc, I just haven't changed it yet. This XS trickery can be avoided, but I like to learn ;)