| Re: DLM's and C code [message #28778 is a reply to message #28749] |
Fri, 11 January 2002 11:26   |
Richard Tyc
Messages: 69
Registered: June 1999
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Member |
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My problem was that the error did NOT occur in the C routine called by
call_external but in other deeply nested routines with no simple means of
getting back to the routine called by CALL_EXTERNAL. Essentially, I adapted
some existing ANSI C code to be called by IDL and added "IDL" specific
features (like the testmodule example in docs for MAKE_DLL ) so I could call
various functions I needed. Unfortunately, major errors in this code were
handled by simple calls to exit() which is not helpful to IDL and it would
also have been a real pain to add returns throughout the many C functions to
return the error back to IDL. Now I can use IDL_MESSAGE with the
IDL_MSG_LONGJMP action.
Rich
Dominik Paul <dpaul@ukl.uni-freiburg.de> wrote in message
news:a1jk1e$f8t$1@n.ruf.uni-freiburg.de...
> Hi Richard,
>
> I do it a little bit easier way. If an error occurs in my C routine (in a
> DLL) I return with an error code, lets say:
> #define ERROR_DIVISION_BY_ZERO -128
> return ERROR_DIVISION_BY_ZERO;
>
> In IDL I can check the return value
>
> status = call_external()
> if status EQ -128 then...
>
> This works really good for me. The calculations which the C routine is
doing
> for me, is written into a piece of memory and can then be seen by IDL.
> Therefor I create a variable in IDL, pass it to my DLL by reference (I
think
> it is the normal way to pass it by referenze), can manipulate the value
and
> on returning to IDL, the variable will hold the new value.
>
> Hope it helps you
> Dom
>
>
> "Richard Tyc" <Richard_Tyc@sbrc.umanitoba.ca> schrieb im Newsbeitrag
> news:a1fsur$78a$1@canopus.cc.umanitoba.ca...
>> A somewhat IDL related question.
>> I am trying to link in some C code via a DLM. I use a wrapper routine to
>> handle the call from IDL and manipulate the args and return data. Within
> the
>> wrapper, I call C functions linked in through another DLL.
>>
>> What is the best way to handle errors while deeply nested within layers
of
> C
>> functions.? The ANSI C code I am using essentially had exit(1) calls
for
>> major errors. Is there an IDL_ function (like say an exit handler) I
can
>> call to cleanly return to IDL rather than a trying to modify the call
> stack
>> and get back to the IDL wrapper function to perform something like a
> return
>> IDL_StrToSTRING("ERROR") ;
>>
>> Thanks
>>
>> --
>> Richard Tyc
>> Project Engineer
>> St. Boniface Hospital Research Center
>> 351 Tache Ave
>> Winnipeg, MB
>> Canada
>> Tel: 204-237-2557
>> Fax: 204-231-0485
>> Email: richt@sbrc.umanitoba.ca
>>
>>
>
>
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