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Mail Archives: djgpp/1997/04/14/17:10:22

From: "Chris A. Triebel" <cat AT sun4 DOT iol DOT unh DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Growing pains with DJGPP
Date: Mon, 14 Apr 1997 14:24:42 -0400
Organization: University of New Hampshire - Durham, NH
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Message-ID: <Pine.SUN.3.91.970414141220.21145F-100000@sun4.iol.unh.edu>
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DJ-Gateway: from newsgroup comp.os.msdos.djgpp

> >
> >My first one would be: how is the portability between DJGPP written
> >under DOS and Linux?
> >Basicly speaking it should be fine, but if anyone has experience with
> >it, I would appreciate any comments.
> I don't know about linux, but I use UNIX at uni and generally I can write a 
> program at home at ftp it to uni. it compiles fine and is going to make 
> assignment a dream :)
>
Personally I have done the same thing, compiling programs on several 
unix platforms, linux, and djgpp fairly efficiently.  Once I had a problem 
where a function was provided by djgpp that wasn't on other unix platforms,
I forget which ... But I do remember finding an alternative function.

> 
> >
> >Second one: I know DJGPP has access to the full Memory in my system
> >(Pmode and that stuff), so we're talking about no more Memory model
> >worrys right? If I felt like it I could construct a two dimensional
> >array with over 64kb of Space? (e.g. char string[32000][32000]) (old
> >BC 3.1 user :-)) I could also just make my heap a few million bytes
> >big and use that as buffer? (not the best idea, I know we're talking
> >theory here)
> I managed to malloc a 128Mb array of ints, and I only have 8Mb of RAM! I was 
> wondering if DJGPP double buffers or something I didn't recieve an error or 
> a NULL from the malloc command.

I don't think double buffering is the correct word here.  I believe the 
word is swapping.  All of memory is divided into pages, when you need a 
page it is brought into memory from a swap space on disk.  When you run 
out of room in memory and you need another page, one is chosen to be 
swapped out -- sent back to the disk -- and the new one is swapped in its 
place.  This is very hardware level stuff.

> 
> >
> >Third: I experimented with Allegro and I found out that when I
> >initialize Keyboard, Timer or something like that and want a
> >return_message (int), the software will not initiallize correctly. As
> >soon as I took out the return int, it went fine. Is that a prob with
> >Allegro? In the short doc it states that one generally isn't
> >interrested in the return code, but I would just like to know if
> >everything went well. It might have been that the author thought that
> >nobody would use it anyways so he might have not taken care of his
> >return code (in-line assembler or so???)
> I couldn't find the putpixel command in Allegro. I searched a dozen .C files 
								      ^^
					I believe that should be .c, there is 
					a difference.
					.c => c language
					.C => C++ language
					( as does .cxx, .cc, .cpp ... )
> (they all #include allegro.h) but I couldn't find the right one. Maybe they 
> should have more internal documentation like:
> 
> /* first.c */
>   function prototype
>   function prototype
>   
> /* second.c */
>   etc.
I don't have allegro handy, but one thing I did at home is used ctags.  vi
supports ctags, emacs supports etags ( essentially the same program I 
think ).

With ctags go to the allegro install directory and type in the following.

ctags src/*.c allegro.h

What this will generate is a tags file which you can read through to find
function definitions and such, or use vi ...

vi -t putpixel

... to look up the function for you.

Just a suggestion.

---
All the above is as true as I know.  Please inform me of errors so that I may
learn from them.  I do like to help out, I just don't always know as much as
I think I do ;)

cat

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