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From: beard@ux1.lbl.gov (Patrick C Beard)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Opening the serial driver.
Message-ID: <4546@helios.ee.lbl.gov>
Date: 2 Jan 90 23:24:18 GMT
References: <3903@atr-la.atr.co.jp>
Sender: usenet@helios.ee.lbl.gov
Reply-To: beard@ux1.lbl.gov (Patrick C Beard)
Organization: Lawrence Berkeley Laboratory, Berkeley
Lines: 45
X-Local-Date: 2 Jan 90 15:24:18 PST

In article <3903@atr-la.atr.co.jp> alain@atr-la.atr.co.jp (Alain de Cheveigne) writes:
>
>
>I'm updating some code according to TN 249 to use OpenDriver() instead
>of RamSDOpen().  I hope in this way to detect when some other terminal
>program has opened the line, to avoid opening twice.  The code I use is:
>	/* MPW C 3.0 */
>	/* test to see if another program owns the serial port */
>	short refnum = aoutRefNum;
>	result = opendriver("AOut",&refnum);
>The result of opendriver() is always -43, which corresponds to fnfErr
>in Errors.h of CInterfaces.
>1) What am I doing wrong?
>

MPW C has lower case equivalents that accept C strings everybody.
Therefore, the call opendriver(char*,short*) takes a  C (i.e. null
terminated) string.  The reason you are getting a fnfErr return code
is that the names for the serial drivers are ".AIn" & ".AOut".  They
have "." characters to avoid conflicts with file names (hopefully).
Therefore, the call

	result = opendriver(".AOut", &refnum);

should work.  The equivalent call using pascal strings is

	result = OpenDriver("\p.AOut", &refnum);

which is more "portable" (between Think and MPW C).  I, for one, will
never use the lower case calls because no other development system
offers them, and I try to keep my strings in pascal form as much as
possible to avoid having to conversions.

On a similar note, does anybody have a library of pascal string manipulation
code lying around?  I guess it would be nice to have all of the regular
C string functions cast in a form to manipulate pascal strings.  I've always
wondered, what do Pascal programmers use to do things like sprintf?




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-  Patrick Beard, Macintosh Programmer                        (beard@lbl.gov) -
-  Berkeley Systems, Inc.  ".......<dead air>.......Good day!" - Paul Harvey  -
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