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From: Martin_Koehling@do.maus.de (Martin Koehling)
Newsgroups: comp.sys.atari.st
Subject: Re: Can GCC treat printer like
Message-ID: <1912@do.maus.de>
Date: 5 May 91 19:10:00 GMT
Distribution: world,comp
Organization: Maus Mailbox Netz - UUCP-Gateway Bremen
Lines: 46


Richard Scott Hall heavy @ zip.eecs.umich.edu wrote:
<1991Apr27.171053.29034@zip.eecs.umich.edu>

>>>Is there a standard filename for the serial port?
>>
>>AUX:
>>
>>For a full list, check the guide to Atari BASIC that should have come
>>with your ST, I think it's in there somewhere.
>>
>
>I have tried this in GCC, but I get a NULL FILE pointer
>when I do an fopen() on it...I am not too sure it works
>unless I did something wrong...
>
>Richard Hall
>University of Michigan

When you tell GEMDOS to Fopen("AUX:",2 /*read/write*/), it will return
0x0000fffeL.
This is the "device handle" for the serial port; it's WORD-negative, but
LONG-positive (BTW: this is _not_ the same as handle 2, which can be
redirected; device handles can't be redirected !).

I think that GCC's fopen() mistakes this for an error code.
Most (if not all) GEMDOS function return LONGs; in particular, the Fopen()
and Fcreate() system calls should always be treated as returning a LONG.

GCC's Fopen should do something like this:

   long err ;
   int handle ;
   err = Fopen(fname,2) ;
   if ( err < 0 )
   {
      return (FILE*)0 ;  /* ... open error ... */
   }
   else
   {
       handle = (int)err ;
   }

I suggest you try to find & fix it in the lib sources...

Martin Koehling