Any thoughts?

Show your code? You can also use a C debugger to try to determine where the problem is. You could also look at FFI in case its source code is of some help.

Sure,

#!/ASPerl/bin/perl 

use strict;
use Inline 'INFO';
use Inline (C => 'DATA',
        DIRECTORY => '/tmp',
        FORCE_BUILD => 1,
        CLEAN_AFTER_BUILD => 1,
        CCFLAGS => '-GF -MDd -Zi /W3 -DWIN32 -D_CONSOLE -DNO_STRICT -D
+_DEBUG'
        . ' -DHAVE_DES_FCRYPT -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_
+SYS'
        . ' -DUSE_PERLIO -DPERL_MSVCRT_READFIX',
        LIBS => 'winmm.lib PAStaticWMMED.lib',
        );


sub my_simpcb {

    my $in = shift;
    my $out = $in;

    return $out;

}


registercb (\&my_simpcb);
portinit (44100, 256);
portstart ();
pasleep (3000);
portstop ();
portclose ();

exit (0);

__DATA__
__C__
#include <portaudio.h>
#include <memory.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>

static int pacback (void *, void *, unsigned long, PaTimestamp, void *
+);

static PortAudioStream *pa_stream;

typedef struct {
    SV *isv;
    SV *cbfn;
    int runcount;
} mybundle;

mybundle bundle;

void portinit (double sps, int buflen) {
    
    bundle.isv = newSVpvn (NULL, buflen);
    sv_setpvn (bundle.isv, "foo", 3);
    Pa_Initialize ();
    Pa_OpenDefaultStream (&pa_stream, 1, 1, paUInt8, 
              sps, buflen, 0, pacback, &bundle);
}

void registercb (SV *cbfname) {  
    bundle.cbfn = newSVsv (cbfname); 
}

SV * whatiscb () { 
    return bundle.cbfn;
}

void pasleep (int milisec) {  
    Pa_Sleep (milisec);
}

void portstart () { 
    bundle.runcount = 0; 
    Pa_StartStream (pa_stream); 
}

void portstop () { 
    warn ("runcount == %d\n", bundle.runcount); 
    Pa_StopStream (pa_stream);
}

void portclose () {

  Pa_CloseStream (pa_stream);
  Pa_Terminate ();

}

static int pacback (void *invoid, void *outvoid, 
            unsigned long nsamps, 
            PaTimestamp outTime, void *user) {
    
    mybundle *intbundle = (mybundle *)user;
    intbundle->runcount += nsamps;

    if (!invoid)
    return 0;

    sv_setpvn (intbundle->isv, (unsigned char *) invoid, nsamps);
    memcpy ((unsigned char *)outvoid, (unsigned char *)invoid, nsamps)
+;
    
    return 0;

}
[download]

I've further narrowed it down to not reading from the variables is what crashes it, but the "sv_setpvn" that _writes_ to the perl variable is what doesn't work. I verified this by adding a sv_setpvn (intbundle->isv, "foo", 3); to it, which also caused it to crash with the "access violation reading..." error.

I've uploaded the portaudio libraries I link against as well as winmm.lib (which is from the platform sdk) to http://web.mit.edu/fustflum/etcetera/portaudio, incase you care to look.

Thanks for any insights you might have.

Thanks for posting that code.

This is mostly just a courtesy note to let you know that I won't have an answer for you, sorry (and I hope it might also increase the visibility of your node, having two "late" replies not just one -- if you get no response within a few days, I'd post a new root node).

The reason I won't have an answer is that I don't do OO in XS and I'm pretty sure that I never will. OO in XS is quite against my philosophy of XS "best practices".

So I have very little idea what bundle.isv actually means under the covers. Though, to be honest, I'm not too surprised that this is the source of your problem (well, that's my conclusion, anyway).

If I were writing this, I'd do all of the OO (and just about anything else I could) in the Perl code (in the *.pm file) and have the XS interfaces be very vanilla C-friendly interfaces (except that some arguments might be of type SV* for the sake of dealing with Perl's total refusal to reasonably deal with memory buffers that it didn't allocate itself).

- tye