NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/comp/sys/atari/st/tech/6540

Text File | 1993-01-08 | 3.1 KB | 64 lines

Newsgroups: comp.sys.atari.st.tech
Path: sparky!uunet!mcsun!sun4nl!spider.research.ptt.nl!ull!marcob
From: [e-mail] (Blom M.A.)
Subject: Re: Porting UNIX Code to the ST
Message-ID: <[e-mail]>
Sender: [e-mail] (USEnet News)
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References: <[e-mail]> <[e-mail]>
Date: Fri, 8 Jan 1993 12:30:49 GMT
Lines: 51

In article <[e-mail]> [e-mail] (John Trickey) writes:
>In article <[e-mail]> [e-mail] writes:
>>
>>I have some code that generates a binary file - I compiled it with GCC 2.3.1
>>and ran it on the ST - it works fine, it generates a binary file; however, the
>>print statements seem to be outputting a CNTRL-M (^M) - I don't need these
>>extra characters what should I do to get rid of them???
>
>
>The problem you have encountered is that Unix treats all files alike while
>DOS, TOS etc do not. In Unix the open is fopen(filename,mode) where mode is
>a char * of "a","r","w","r+","w+","a+". In TOS these are for text files with
>CRLF being converted to LF on input and LF being converted to CRLF on output.
>Note CR is ^M.
>To switch this off you need to open the file in binary mode. These modes
>are "ab","rb","wb","rb+","wb+","ab+". The format "r+b" etc is also acceptable.
>

Actually, in the Mint library there is a function for this called _binmode().

Quote from the source of _binmode():
 *      if called with TRUE, then subsequently all fopens have _IOBIN
 *      by default  on open. This will make life much easier for
 *      people who have been using the Gnu lib (any my job with the compiler
 *      much easier too, don't have to go hunting for fopens())

In other words, _binmode(TRUE) makes sure that all calls to fopen()
automatically open files in binary mode.

Unfortunately, this doesn't solve the problem for programs that use stdout
to write (binary) results to a file, i.e. programs that simply use printf()
and rely on IO-redirection from within a shell. Many Unix programs do this
(pbmplus, cjpeg, djpeg, etc.) The problem with this is that stdout is
already open, and NOT in binary mode. There doesn't seem to be a (legal) way
to set stdout to binary mode. Still, there is a trick, but it only works with
gcc (I still use version 1.39 or so) and the MiNT library. It may NOT even work
with future versions of the MiNT libraries. OK, now for the trick:
In main(), before any output is sent to stdout, I add this to the code:

stdout -> _flag |= _IOBIN;

This sets stdout to binary mode. It relies on how the MiNT library internally
represents and deals with files. I've successfully compiled djpeg en cjepg
(version 4) with this trick without changing anything else in the code.
I also used it to compile the previous (=old) version of pbmplus.

Perhaps someone working on the MiNT library could add a function to the library
that sets stdout to binary. This would make porting Unix programs somewhat
easier. And it would turn this trick into a feature :-)

Marco Blom.