in reply to Re: XS: Passing an external library's function a Perl XS callback
in thread SOLVED: XS: Passing an external library's function a Perl XS callback

I see where you declare PerlInterpreter *mine to hold the Perl context, but where you assign it?

In his linked example, BrowserUk has:

void setCallback( SV *cb1, SV* cb2, SV *cb3, SV *cb4 ) {
    saved = Perl_get_context();

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but I don't see an equivalent in your code.

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Re^3: XS: Passing an external library's function a Perl XS callback
by pRiVi (Initiate) on Jan 06, 2019 at 00:05 UTC
    I can confirm that you have to run
    mine = Perl_get_context();

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    before you can use this. The run of 
    dSP;

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    just segfaults if 
    mine

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    have not been set via 
    mine = Perl_get_context();

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    I call on initialisation of my module a XS function which does does do
    mine = Perl_get_context();

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    and verify that mine is not NULL before trying to call a perl function.

    All I needed is the following to get it working, and call the function "functionname" within of the module I called "setcallback" from.
    The use in C: 
    void dorunperlfunction() {
   if (mine) {
      PERL_SET_CONTEXT(mine);
      dSP;
      ENTER;
      SAVETMPS;
      PUSHMARK(SP);
      PUTBACK;
      call_pv("functionname", G_DISCARD|G_NOARGS);
      FREETMPS;
      LEAVE;
   }

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    The initialisation in XS(!): 
    PerlInterpreter * mine = NULL;
...
void
setcallback()
   CODE:
      ...
      mine = Perl_get_context();
      ...

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