Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Thanks, But it still is a mystery... By using "int & " instead of "int *", the C-code looks alright and the C-function is called with the right parameters. But the value that the C-funtion writes to the int pointers are not passed back to perl.

Example in the generated C-file:

XS_EUPXS(XS_TellStick_tdSensor); /* prototype to pass -Wmissing-protot +ypes */ XS_EUPXS(XS_TellStick_tdSensor) { dVAR; dXSARGS; if (items != 6) croak_xs_usage(cv, "protocol, protocolLen, model, modelLen, id, d +ataTypes"); { char * protocol = (char *)SvPV_nolen(ST(0)) ; int protocolLen = (int)SvIV(ST(1)) ; char * model = (char *)SvPV_nolen(ST(2)) ; int modelLen = (int)SvIV(ST(3)) ; int id = (int)SvIV(ST(4)) ; int dataTypes = (int)SvIV(ST(5)) ; int RETVAL; dXSTARG; printf("id1: %d\n", id); RETVAL = tdSensor(protocol, protocolLen, model, modelLen, &id, &da +taTypes); printf("id2: %d\n", id); XSprePUSH; PUSHi((IV)RETVAL); } XSRETURN(1); }
I added two printf for debugging (best debug tool...) and when I run it with like this:
... my $sensorId = 1; TellStick::tdSensor($protocol, 25, $model, 25, $sensorId, $dataTypes); print "protocol: $protocol, model: $model, sensorId: $sensorId, dataT +ypes: $dataTypes\n"; I get the output id1: 1 id2: 51 protocol: mandolyn, model: temperaturehumidity, sensorId: 1, dataTypes +: 2
So it gets the correct value (51), but that is not passed back.

It looks like the XS code only sees the id parameter as an input value (casting it right), but no output is generated (except the return value). The string arguments (protocol, model), seems to work in modifying what the value is pointing to.

Should I somehow use "int *" in the XS anyway, but writing some special code for INPUT/OUTPUT in the typemap? Or is there some other way of returing the correct value?

In reply to Re^2: Passing integer pointer in XS? (&) by martin67
in thread Passing integer pointer in XS? by martin67

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others lurking in the Monastery: (3)
As of 2022-11-29 04:38 GMT
Find Nodes?
    Voting Booth?