Mail Archives: djgpp/1996/12/05/06:26:14
camorgan AT amoco DOT com wrote:
>
> Hi!
>
> I have the DJGPP C compiler and like it very much. However, I am trying
> to compile a standalone executable in DOS 6.21 for someone else who does
> not have the DPMI server. From the FAQ documentation, it appears there
> is a way to do this. I refer to the following FAQ section:
Before embarking on an attempt to help you with PMODE/DJ, I want to say
that the easiest, simplest, and most efficient way to ensure that any
distributed program will have DPMI is simply to package it with
CWSDPMI.EXE. If your program doesn't find a resident DPMI host, it will
look for CWSDPMI in its own directory or in the PATH. Many commercial
programs include DOS4GW.EXE, which serves an identical function, so
doing it for DJGPP packages can't be that terrible. Moreover, CWSDPMI
is more than twelve (!!) times smaller than DOS4GW, so its meager 20K
isn't going to hurt the size of your distribution.
That said...
> I do not understand these instructions! First of all, I am given a
> method (under "How to Use" above using the "copy /B" command), then
> later on a pitfall says this won't work and to "relink the image" (what
> is an "image"?) Object code?) using the CRT1.o file that is included.
> How is this done? I thought you could only relink "*.o" files; in other
> words, how do I specify my *.EXE file as input along with the CRT1.O
> file?
>
> What is a "coff image"? Re the TSR method: What is "stubedit"? How
> would I "change the filename of the DPMI provider to PMODETSR.EXE"?
>
> I would appreciate a further explanation of the above in layman's
> terms!
The reason the instructions are the way they are is that the method they
recommend SHOULD work, but don't because of a minor incompatibility
problem. In layman's terms, here's what you need to do to work around
the problem:
1) Put the included file "crt1.o" in the same directory as your program.
2) Recompile the program, including crt1.o on the command line. Thus,
gcc -Wall -g -O -o myprog.exe main.c stuff.c morestuf.c
becomes:
gcc -Wall -g -O -o myprog.exe main.c stuff.c morestuf.c crt1.o
This method should work, but I should warn you in advance that I haven't
tested it. :) If you use RHIDE, you can specify additional files to
link using the menus, but I'm not familiar enough with the interface to
tell you how.
Okay, on to the terms:
"image" - The actual compiled code of your program, not including any
of the extra stuff it needs to run, like the stub loader. If you don't
tell gcc what file to output, i.e., omit the '-o' parameter, it
generates "a.out", and "a.exe". "a.out" is the image; it's a complete
program, but it can't run yet. "a.exe" is the image that has been
prepended with a 2K stub which handles invoking DPMI and loading your
program.
"object code" - The actual machine language instructions generated by
the compiler. Object code is stored in two forms: an intermediate form
called an "object file" that only includes the code that you yourself
have written, stored with the extension '.o'; and a form that has been
linked with the code for all the functions you call in your program but
don't actually write (like printf, etc., called "library code"). This
final form is known as the "image".
"coff" - One of many formats for storing object code in files. DJGPP
uses the COFF format, so its images and object files are called "COFF
images".
A TSR is a program that remains in your computer's memory after it is
run. Examples: DOSKEY, MSCDEX, all mouse drivers, COMMAND.COM, virus
software, network drivers, CWSDPMI, etc. The "PMODETSR" program is a
memory resident version of the PMODE extender.
"stubedit" is a DJGPP utility that lets you modify the runtime
parameters of your programs, including what they call themselves, what
actual program they run, the amount of stack space and transfer buffer
space they are allocated (if you don't understand this, don't worry),
and the default DPMI host they use. To change the DPMI host of your
program to PMODETSR, just type the following command:
stubedit myprog.exe dpmi=PMODETSR.EXE
This is somewhat silly however, because if you are going to use a
resident DPMI host, you may as well use CWSDPMI, because it does a
better job.
Many of these concepts are covered in various C references and courses,
and a basic grounding in them as they apply to DJGPP can be found by
reading the DJGPP Frequently Asked Questions list (v2/faq202b.zip). The
first 4-6 chapters can be particularly enlightening for those who are
inexperienced with DJGPP concepts. :)
--
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| John M. Aldrich, aka Fighteer I | fighteer AT cs DOT com |
| Proud owner of what might one | http://www.cs.com/fighteer |
| day be a spectacular MUD... | Plan: To make Bill Gates suffer |
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