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From: barsh@stsci.UUCP
Newsgroups: comp.os.vms
Subject: Re: Using System service in VAXC
Message-ID: <106@ra>
Date: Mon, 23-Nov-87 14:33:24 EST
Article-I.D.: ra.106
Posted: Mon Nov 23 14:33:24 1987
Date-Received: Thu, 26-Nov-87 05:46:15 EST
References: <8711230601.AA23969@ucbvax.Berkeley.EDU>
Organization: Space Telescope Science Institute, Baltimore, MD 21218
Lines: 54

in article <8711230601.AA23969@ucbvax.Berkeley.EDU>, NIELAND@FALCON.BERKELEY.EDU (Ted Nieland - SRL) says:
> But the VAXC equivalent:
> 
> read_key_vax(key)
> char *key;
>   short int channel,status;
> #include <iodef.h>
>   int sysqiow(),sys$assign();
> 
> 	status = sys$assign("sys$input",channel,,);
> 	status = sys$qiow(,channel,IO$_READVBLK + IO$M_NOECHO + IO$M_CVTLOW
>                  ,,,,*key,256,,,,);
> }
> 
> Doesn't compile because it doesn't like the extra commas in the qiow statment.
> 
> Any ideas out there


1.  You can put zero's in for parameter's you don't use.
2.  you must use a string descriptor to pass string's to VMS

	i.e.  your "sys$input" will not work since it is a "C" string

	#include <descrip>

	$DESCRIPTOR(sinp, "sys$input");
	status = sys$assign(&simp, &channel, 0, 0);
	etc...

3.  You must pass string descriptors by address, hence, the above 
    ampersand in passing simp.

4.  channel number in sys$assign must be passed by address if I remember
    correctly.

5. When specifying things like your lists in qio, you should OR in the
   values (i.e. IO$_READVBLK | IO$...) instead of adding them.

6. The system service manual specifies exactly how to pass parms to
   each ss, if you don't follow them exactly...

If this doesn't help, I can come up with a working sample of this
in a few minutes, just let me know...


					jrbii
					~~~~~
 
-- 
	        John Barshinger	
		Space Telescope Science Institute
		Baltimore, MD 21218
		plink:jrbii | bix:jrbii | barsh@stsci.edu