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Passing file LUN to C routine [message #34993]

Tue, 06 May 2003 11:22

btt
Messages: 345
Registered: December 2000

Senior Member

Hello,

I have IDL interfaced (via DLM in C) with a frame grabber for collecting
video. I want to pass a file's LUN to C (repeatedly) so that the C
routine can write the most recent frame to to the file. My idea is to
place IDL in an interruptable loop (widget timer); in each iteration the
C routine is passed the LUN, writes the image and then returns a flag
such as the number of bytes written to IDL. Later I'll poke around with
the images by using an ASSOCiated variable within IDL.

It's a reasonable plan that is rapidly going amuck; what I have tried so
far causes IDL to crash. I have been using the IDL_FileStat() function
to get the required FILE pointer for C. The compiler doesn't C complain
about the setup; but it kills IDL when I run it. Methinks
IDL_FileStat isn't my friend anymore.

So ...

(1) How do I properly convert the LUN in IDL into a FILE pointer? (I
guess the question maybe better phrased as how do I get IDL to give me
the FILE pointer associated with the LUN I pass?) I think I need this
because the C routine fwrite requires it.

(2) Is this creating an unstable situation by leaving the file open all
the time until some condition is met in IDL?

(3) Would I be better off passing the filename to C and having C
open-write-close for each iteration?

Thanks,
Ben

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[Message index]

		Passing file LUN to C routine By: btt on Tue, 06 May 2003 11:22
		Re: Passing file LUN to C routine By: btt on Wed, 07 May 2003 06:54
		Re: Passing file LUN to C routine By: Stein Vidar Hagfors H[2] on Mon, 12 May 2003 08:25
		Re: Passing file LUN to C routine By: Nigel Wade on Wed, 07 May 2003 02:56
		Re: Passing file LUN to C routine By: btt on Mon, 12 May 2003 09:33
		Re: Passing file LUN to C routine By: Stein Vidar Hagfors H[2] on Fri, 16 May 2003 10:45
		Re: Passing file LUN to C routine By: btt on Mon, 19 May 2003 05:33

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