If you are new to DJGPP, I suggest that you read more about it first before downloading the entire package from ftp sites on the Internet.
DJGPP is a free yet powerful 32-bit C/C++ development system for Intel 80386+ PC's. It includes ports of many GNU development utilities.
The main site is located at DJ Delorie's Home Page where the most up-to-date information is available, including announcements, bug reports and fixes, FAQ lists, an online topic search program, software contributions, and more.
If you are new to DJGPP, I suggest that you read more about it first before downloading the entire package from ftp sites on the Internet.
First things first, so get the FAQ lists faq102.zip and faq201b.zip, and read them carefully, especially Sections 1-3, which will help you get started.
The current versions of DJGPP are v1.12 and v2.00. I highly recommend v2, as has many advantages over v1, such as better ANSI-compliance, etc.
Getting the documentation and reading them is very important. Online docs for DJGPP are in the txi*.zip package; also, each module has its own separate manual.
The two versions of DJGPP have slightly different setups. Click on the version number to obtain specific information on each setup.
All files should be unpacked by "pkunzip -d -o -n file.zip" or "unzip -fo file.zip." Maintenance files have to be installed last and in order: m1, m2,... After unzipping a maintenance file, you need to run a batch file that it installs before continuing with the next maintenance file.
There is also a minimal DJGPP package described in Section 3.6 of the FAQ list. The EZ-GCC version is about 5M compressed. Note: This is DJGPP v1.1x! You REALLY should get v2.00 as it is much better.
To build (compile and link) your files, just type "gcc -o output input..." A coff binary would be produced using v1.12, and an exe file with v2. To run the file in v1.12, just do "go32 output", or in v2, type "output".A coff binary produced by v1.12 can be converted to an exe file by "coff2exe hello".
For v2, make sure you are running under a DPMI server (QDPMI, Windows, OS/2, etc.) or CWSDPMI.EXE (from the csdpmi*.zip file) is in the current directory or path.
Some short examples:
gcc -c input.c
gcc -o output input.c (v1.12)
gcc -o output.exe input.c (v2)
To execute, type "go32 output" (v1.12) or "output.exe" (v2)
gcc -o output file1.c file2.c file3.s
To execute, type "go32 output" (v1.12) or "output.exe" (v2)
Notice the .c and .s file extensions. Input files could be .c, .cc, .cpp, .s (asm), etc. See the FAQ list and read the docs for more information.
Libraries can be linked in using the -l switch. You should always put them last on the command line. The standard C library (libc.a) is linked in automatically so you don't have to specify it for most of your programs. If you need to link in multiple libraries, just remember that the correct order has to be "-lall_other_libs_first -lgpp -lm -lpc".
Some short examples:
gcc -o output input -llib1 -llib2 -llib3...
Suppose you're using c++ iostream code in your hello.cpp program
gcc -o output input.cpp -liostr
Look inside the djgpp\lib directory. The file corresponding to "-liostr" is libiostr.a. The standard C library, contained in djgpp\lib\libc.a, is linked in using "-lc". See a pattern? In general, libX.a in djgpp\lib corresponds to "-lX" on the command line.
Please refer to the docs for more information on the various standard libraries that come with DJGPP.
One more thing, the standard C library is automatically linked in by the compiler so "-lc" is, most of the time, unnecessary.
gcc -o output input.c -lmylib1 -lgpp -lpc
A very important thing to remember is that DJGPP behaves unpredictably for different orders of libraries given on the command line. If you are linking in multiple libraries, the correct order is "-lall_other_libs -lgpp -lm -lpc".
Some short examples:
gcc -Wall -o input input
gcc -O1 -o output input
gcc -O2 -o output input
gcc -g -o output input
gcc -Wall -O2 -g -o output input
In general, there is no necessary order of switches on the command line. Just remember that "-llib"'s come last, and they follow some order among themselves.
gcc -Wall -O2 -g -o hello hello.c foo.o bar.s -lacmelib -lm -lpc
To debug programs in v1.12, type "go32 -d [debugger-name] [program] [args...]." If you installed the GNU debugger, the debugger-name is gdb. There are other debuggers available at the Oak site; also, note that there are two versions of each, dpmi and non-dpmi, so use the correct one depending on your programming environment. Section 12 of the FAQ list explains more on debugging programs.
To debug programs in v2, type "gdb [program.out] [args...]." Make sure you built the program with the "-g" switch. [program.out] is not the exe but rather the coff image. Read the FAQ list and gdb docs for more information on using gdb.
There's another tool that is very helpful in debugging crashed programs (v1.12 or v2) that produce a trace-back on the screen (GPF message and register dumps). Make sure the program was built with the "-g" switch, and the coff image and source files are in the same dir. Then type "symify [program]" right after the program crashes and it'll show the line numbers in the source code where the program crashed.
To profile your code (v1.12 or v2), build with the "-pg" switch, run your program, then run "gprof [program.out]." [program.out] should be the coff image, rather than exe. Note that for v1.12, gprof does not work under DPMI. Read the FAQ list and gprof docs for more information on this.
If you want to test whether your installation went smoothly, you can get the djtst*.zip file from the same place you got DJGPP from. Run the batch file and it will automatically do the compilation, linking, and testing.
People ask about IDE's, too. GNU Emacs has been ported to DOS, you might want to try that. I've also seen some nice enhanced editors/IDE's, try Aurora, Multi-Edit, or Boxer editor. I often use DOS Edit, with batch and make files. =)
There's a neat Borland-like IDE for DJGPP called RHIDE. Get it from http://www.tu-chemnitz.de/~rho/rhide.html.
Some more little tips: if your first program doesn't seem to want to compile/link, try doing "set > myenv.txt" at the prompt, and examine the myenv.txt file. See if your environment variables are properly set, as described here.
DJGPP might complain "Out of virtual memory" in an OS/2 DOS box; it has happened to me before. Just right click to get to the DOS box properties, and increase (DPMI) memory OS/2 gives it. Mine is set to 256M|ENABLED.
Redirecting stdout doesn't work very well under a plain DOS shell. Try using a smarter shell such as 4DOS. There's also another solution to this problem using the redir program, search for it in the mail archives.
First, read the FAQ list; try to see if what you're looking for is already there.
There are online docs in DJGPP; they are in the txi*.zip package. If you installed it, just type "info" to get into the top help node, or "info [topic...]" to go directly to a particular topic. Use the Tab, space-bar, Return , 'n', 'p', 'u' keys, etc. to navigate between pages and topics. Press 'q' to quit.
There is also a DJGPP newsgroup on Usenet and a DJGPP mailing list. (I think mail goes through the newsgroup so you don't need to subsribe to both.) The newsgroup name is "comp.os.msdos.djgpp"; to subsribe to the mailing list, send mail to listserv@delorie.com, with no subject and write "add [your e-mail address] djgpp" in the body. If you only want announcements, write "add [your e-mail address] djgpp-announce."
Another way to get more information on something is to search the mail-archives at the Turnbull site or DJ's homepage. I find many useful articles there.
9/28/96 icbm on EFNET IRC #c and #gamecode.
Mail me corrections/suggestions/complaints/crap at avly@remus.rutgers.edu
Copyright (C) 1995-96 avly@remus.rutgers.edu All Rights Reserved
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