comp.lang.idl-pvwave archive: archive » Re: Can't pass data with CALL

Home » Public Forums » archive » Re: Can't pass data with CALL_EXTERNAL to C function

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Can't pass data with CALL_EXTERNAL to C function [message #60842 is a reply to message #60835]

Fri, 20 June 2008 04:18

Allan Whiteford
Messages: 117
Registered: June 2006

Senior Member

Dan wrote:
> Hi everyone,
>
> I am having problems sending data to my C function through
> CALL_EXTERNAL. Specifically, I send the data, but it seems as if all
> the variables passed to the C function are suddenly 0 (maybe
> uninitialized). I have posted my test code below. Please take a
> look, any help would be greatly appreciated. It is also probably
> worth mentioning that when I return something from the function (like
> return 2;) or something like that, the IDL value will be 2 (i.e.
> values are returned correctly, so I know the function is at least
> running to completion).
>
> ----- CODE -----

<snip>

Dan,

It's hard to see/test exactly what you're doing as some of your lines
have been truncated (unfortunately the important line including
call_external).

However, the following is a short example of something which goes along
the lines of what you're doing and works ok for me:

passref.pro
-----------

pro passref
a=fltarr(100,100)
b=fltarr(200,200)

a[17,23]=3.14
b[52,79]=2.72

junk=call_external('passref.so','passref',a,b)

print,a[12,54]
end

passref.c
---------

#include <stdio.h>
#include "idl_export.h"

void do_work(float *a,float *b)
{
a[12+54*100]=1.62;
printf("%f\n",a[17+23*100]);
printf("%f\n",b[52+79*200]);
}

IDL_VPTR passref(int argc, IDL_VPTR argv[])
{
do_work((float *) argv[0],(float *) argv[1]);
}

Compilation
-----------

gcc -I/usr/local/rsi/idl/external/include \
-shared passref.c -o passref.so

I hope this helps. If you can repost your original example without the
lines being cut off then probably someone can point out the exact part
you'd need to change to get it working. In particular, the keywords
you're giving to call_external are probably important.

Thanks,

Allan

Report message to a moderator

[Message index]

		Re: Can't pass data with CALL_EXTERNAL to C function By: Dan[1] on Fri, 20 June 2008 10:30
		Re: Can't pass data with CALL_EXTERNAL to C function By: Trae on Fri, 20 June 2008 07:56
		Re: Can't pass data with CALL_EXTERNAL to C function By: Allan Whiteford on Fri, 20 June 2008 04:18
		Re: Can't pass data with CALL_EXTERNAL to C function By: Brian Larsen on Thu, 19 June 2008 14:27
		Re: Can't pass data with CALL_EXTERNAL to C function By: Dan[1] on Thu, 19 June 2008 12:32
		Re: Can't pass data with CALL_EXTERNAL to C function By: Brian Larsen on Thu, 19 June 2008 11:46

Previous Topic:	Re: Implementation of G Statistic in IDL
Next Topic:	Multidimensional arrays and CALL_EXTERNAL

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Fri Oct 10 11:56:41 PDT 2025

Total time taken to generate the page: 1.84155 seconds