!Sorry -- retry : Faq v0.2
Thu, 24 Oct 96 16:33:53 CST
Hello folks,
Seems this crappy M$dos email proggy is not capable of attaching unix text
:-(
Let me try again:
This is Info file FAQ, produced by Makeinfo-1.64 from the input file
faq.texi.
Revision 0.2 of 24 October 1996
Author: J.J. van der Heijden
What is GNU Pascal?
*******************
The purpose of the GNU Pascal project is to produce a Pascal compiler
(called GNU Pascal or GPC) which
* combines the clarity of Pascal with powerful tools suitable for
real·life programming,
* supports both the Pascal standard and the Extended Pascal standard
as defined by ISO, ANSI and IEEE. (ISO 7185:1990, ISO/IEC
10206:1991, ANSI/IEEE 770X3.160-1989)
* supports other Pascal standards (UCSD Pascal, Borland Pascal,
Pascal-SC) in so far as this serves the goal of clarity and
usability,
* may be distributed under GNU license conditions
* can generate code and run on any computer for which the GNU C
compiler can generate code and run.
Pascal was originally designed for teaching. GNU Pascal provides a
smooth way to proceed to challenging programming tasks without learning
a completely different language.
What is the current version of GNU Pascal?
==========================================
The last official release is GPC 1.1, based on GCC version 2.6.3.
GPC version 1.2, based on GCC 2.7.2 is currently in beta testing.
Where is the GNU Pascal FTP site? WWW?
======================================
The master FTP site for GNU Pascal is kampi.hu.fi GNU Pascal related
files can be found in:
ftp://ftp.kampi.hut.fi/jtv/gnu-pascal/
This site is mirrored on:
ftp://sunsite.doc.ic.ac.uk/gnu/pascal/
The latest developer releases can be downloaded from:
ftp://agnes.dida.physik.uni-essen.de/
Also, we have a homepage on the web:
http://agnes.dida.physik.uni-essen.de/~gnu-pascal/
Is it compatible with Turbo Pascal (R) ?
========================================
GPC is currently *not* a drop-in replacement for Borland's Turbo
Pascal (R). It supports a number, but not all of the Borland
extensions to the Pascal language. There is no replacement for most of
the Borland runtime library functions. GNU Pascal is part of the GNU
project, so portability is one of its primary goals. For this reason,
non-portable features of Borland Pascal will probably not be included
into GNU Pascal. More information can be found in the section "Borland
Pascal" of the GPC manual.
Installation related questions
******************************
This section discusses some common problems with the installation of
GNU Pascal.
Which platforms are supported by GNU Pascal?
============================================
GPC uses the GCC backend, so it should run on any system that is
supported by GNU CC. This includes a large variety of Unix systems,
MS-DOS, OS/2 and Win32. A full list of platforms supported by GCC can
be found in the file "INSTALL" of the GCC distribution. Not all of
these have actually been tested, but the gpc-1.2 pre-release is know to
run on these platforms:
i486-linux (Linux 2.x, ELF)
i486-linuxaout
i486-linuxoldld
i486-freebsd2.1
i386-cygwin32 (Windows95/Windows NT)
i386-djgppv2 (MS-DOS)
i386-emx (OS/2, MS-DOS)
mips-sgi-irix5.3
>>> Ok people - send us your success stories, with canonical machine
name! <<<
Which components do I need to compile Pascal source code?
=========================================================
A complete Pascal compiler system should at least have:
* The actual compiler, GPC.
* Assembler, linker, librarian and friends.
* A C library.
* A debugger, if you want to debug your programs.
You don't need a C compiler to compile your Pascal programs, but you
do need it to build the GNU Pascal compiler itself. GNU Pascal version
1.1 is based on GCC 2.6.3, GPC v1.2 is based on GCC v2.7.2 Any attempt
to build GPC with the wrong version of GCC is bound to fail.
For most people, the GNU binutils and GNU debugger (gdb) are a good
choice, although some may prefer to use vendor specific tools.
Help! linking gpc1 fails: _emit_string_move undefined (and more)
================================================================
If linking `gpc1' bombs out with an error message that looks like
this:
ld: Undefined symbol
_emit_string_move
_emit_string_pad
_maybe_find_function_data
_dbxout_set_type_status
_version_flag
*** Error code 1
make: Fatal error: Command failed for target `gpc1'
you probably suffer from a VPATH make problem. A few GPC source
files have counterparts with identical name in the GCC source
directory. When you have built GCC in the GCC source directory and you
are not using a recent version of GNU make this problem may occur.
There are three solutions:
* Get a recent version of GNU make. Version 3.74 or better is known
to work.
* Build GCC in a seperate directory instead of using the GCC source
directory.
* Manually delete these files from the GCC object directory:
`stor-layout.o dbxout.o expr.o fold-const.o optabs.o convert.o'
`function.o setop.o toplev.o'
then resume `make'.
When I build libgpc.a, rts-rt0.c says: SIGXCPU undefined (and more)
===================================================================
Compilation of the runtime system may fail in rts-rt0.c with a
message simular to this:
rts-rt0.c: `SIGXCPU' undeclared (first use this function)
or:
rts-rt0.c: storage size of `sv' isn't known
rts-rt0.c: storage size of `osv' isn't known
If this happens to you, you have to edit the rts/rts-config.h file
and comment out the last line to:
/* #undef HAVE_SIGSYS */
This will be fixed in a future release.
I'm using unix, and all my Pascal programs have linking problems.
=================================================================
A number of unix configurations use their system's linker instead of
GNU ld. Usually, GPC and GCC need a program called `collect2' before
calling the system's `ld'. `collect2' is installed by GCC, and if you
only install GPC, it will not find collect2, and use the system linker
directly, which will result in various linker errors. The solution is
to copy `collect2' by hand from the GCC directory to the location where
`gpc1' lives.
I do I debug my Pascal programs?
================================
To debug your programs, (a) GNU Pascal must be able to generate
executables with debug info for your platform, and (b) you must have a
debugger which understands this.
* If `gpc -g -o hello hello.p' says: "gpc: -g not supported for this
platform", then GPC is unable to generate debug info. Usually,
installing GAS instead of your system's assembler can overcome
this. When you configure the GCC used for GPC, specify
"-with-gnu-as", and possibly "-with-gnu-ld" and/or "-with-stabs".
More information can be found in "INSTALL" file in the GNU CC
source directory.
* Your system's debugger may not understand the debug info generated
by GNU tools. In this case, installing GDB may help.
The bottom line: if you can debug GCC compiled programs, you should
be able to do this with GPC too.
The GNU debugger (GDB) currently does not have a "Pascal" mode, so
it is unable to display certain Pascal structures etc. When debugging,
please note that the Initial Letter In Each Identifier Is In Upper Case
And The Rest Are In Lower Case. If you want to display variable 'foo'
in the debugger, type `show Foo' or `display Foo' instead.
Can you recommend an IDE?
=========================
Users of Borland Pascal may wonder if there's a replacement for the
IDE (Integrated Development Environment). Here's a few suggestions:
* *(X)Emacs*. Some people think it's the answer to the question of
Life, the Universe and Everything, others decide it's uGNUsable.
Available from your friendly GNU mirror.
* *XWPE* is an immitation of the Borland IDE, so users of Borland
Pascal may find it a good alternative.
Although GDB is an excellent debugger, it's user interface is not
very attractive. Refer to the comp.windows.x FAQ: "Where can I get an
X-based debugger?" at:
http://www.cis.ohio-state.edu/hypertext/faq/usenet/x-faq/part6/faq-doc-2.html
Some useful frontends include: XXGDB, tGDB and XWPE. see:
http://www.ee.ryerson.ca:8080/~elf/xapps/Q-IV.html
Very nice, but resource consuming is the Motif based DDD:
http://sol.ibr.cs.tu-bs.de/softech/ddd/
Do we have a binary for you?
============================
Currently, we have binaries for these platforms:
i486-linux (ELF)
i486-linuxaout
i486-linuxoldld
djgpp V2 (msdos)
emx 0.9B (OS/2, msdos)
cygwin32 beta16 (Windows95, Windows NT)
mips-sgi-irix5.3
New binaries may have been added after the release of this FAQ.
GNU Pascal and your system libraries
************************************
This section discusses common problems people have when they try to
access their system's libraries.
How do I use from the C library?
============================================================
GNU Pascal can use every function of your C library, but it may be
up to you to write declaration of an external function, before you can
use it. Consider the function `sleep'. man(3) sleep reveals:
---------------------------------------------------------
NAME
sleep - Sleep for the specified number of seconds
SYNOPSIS
#include
unsigned int sleep(unsigned int seconds);
---------------------------------------------------------
This small demo program shows how to use `sleep' in a Pascal program:
---------------------------------------------------------
program SleepDemo;
type
word = __unsigned__ integer;
function sleep(seconds: word): word; C;
var
result : word;
begin
result := sleep(10);
end.
---------------------------------------------------------
What's this confusion about Pascal and C style strings?
=======================================================
It is important not to confuse Pascal and C string types.
* The Pascal string schema, as defined in section 6.4.3.3.3 of the
ISO-10206:1990 Extended Pascal standard, is a record:
type string = record
Capacity : integer;
length : integer;
string : packed array [ 1..Capacity ] of char;
end;
'string' is not 'string(256)', unlike Turbo Pascal. The capacicty
must be declared:
type
MyString = string(256);
before it can be used, i.e.:
function MyFunction: MyString;
* A C string ( "char *" ) is an array of char, terminated with a
NULL char.
C library functions require C, not Pascal style string arguments!
Consider this code snippet to convert Pascal style strings to C style
and vice versa:
---------------------------------------------------------
type
word = __unsigned__ integer;
TString = string(256); { Pascal string schema }
CString = __cstring__; { C style string }
{ Convert a "C" string to a "Pascal" string }
function StrPas(Src: CString): TString;
var
S : TString;
begin
S := '';
if (Src <> NIL)
then while ( (Src^ <> chr(0)) AND (length(S) < S.capacity)) do
begin
S := S + Src^;
inc(Word(Src));
end;
StrPas := S;
end;
{ Convert a "Pascal" string to a "C" string }
function StrPCopy(Dest: CString; Src: String): CString;
var
c: integer;
p : CString;
begin
p := Dest;
for c:=1 to length(Src) do
begin
p^ := Src[c];
inc(word(p));
end;
p^ := chr(0);
StrPCopy := Dest;
end;
---------------------------------------------------------
Then this small example will print the PATH:
---------------------------------------------------------
Program EnvDemo;
{ include the above StrPas() and StrPCopy() snippet here }
{ C library function prototype: char *getenv(const char *name); }
function GetEnv(name : CString): CString; C;
var
pName: CString;
begin
getmem(pName, 256);
pName := StrPCopy(pName, 'PATH');
writeln('Your PATH is: ', StrPas(GetEnv(pName)));
freemem(pName, 256);
end.
---------------------------------------------------------
And this is how you access the 'system()' call in you C library:
---------------------------------------------------------
program SysCall;
{ include the above StrPas() and StrPCopy() snippet here }
function system(name : CString): integer; C;
var
pName: CString;
result : integer;
begin
getmem(pName, 256);
pName := StrPCopy(pName, 'ls -l');
result := system(pName);
writeln('system() call returned : ', result);
freemem(pName, 256);
end.
---------------------------------------------------------
There may be other ways to do the same thing; you could declare a
type PChar instead of CString:
type PChar = ^char;
and replace all references to `CString' with `PChar'. Do NOT pass a
"C" style string as a var-argument if the C prototype says "const char
*" or you will get a coredump.
You are right if you think this stuff belongs in a library, to be
distributed with GPC. Have patience, or start coding!
Are GNU Pascal objects compatible with GNU C++ classes ?
========================================================
No. (This may change in a future version)
Where are the Turbo Pascal (R) replacement units?
=================================================
They don't exist (yet). Most of their fuctionality can easily be
implemented, some things are very x86/msdos dependant and would be
meaningless on any other platform.
How do I build/use a shared library?
====================================
(topic under construction)
GNU Pascal on the djgpp (MS-DOS) platform
*****************************************
This chapter discusses some potential problems with GNU Pascal on
MS-DOS, using djgpp.
If you need more information
============================
GPC/djgpp is a djgpp V2 application, and most of the djgpp
documentation applies for GPC too. A great source of information is the
djgpp FAQ:
http://www.delorie.com/djgpp/v2faq/faq202b.zip
Another place to look for DJGPP documentation is the DJGPP Knowledge
Base, at this URL:
http://www.delorie.com/djgpp/doc/kb/
What do I download?
===================
As discussed in section 2.2, other than GPC itself, you need an
assembler, linker and friends, a C library and possibly a debugger.
>From your local djgpp mirror, you can get these as:
v2/djdev200.zip (C library)
v2gnu/bnu252b.zip (assembler, ....)
v2gnu/gdb412b.zip (debugger)
The rest is up to you; 'make' (v2gnu/mak372b.zip) can be useful,
RHIDE (an IDE with Borland-look) is nice, but still under development.
Future releases of RHIDE may have better GPC support.
How do I install the compiler?
==============================
If you don't have djgpp installed on your harddisk, create a
directory for GNU pascal ("c:\gpc"), and unzip the archives. Make sure
you preserve the directory structure (use "pkunzip -d"). Now, add the
directory where gpc.exe lives ("c:\gpc\bin") to your path and set the
DJGPP environment variable to point to your djgpp.env file:
set DJGPP=c:\gpc\djgpp.env
Then, add this to your djgpp.env file:
---------------------------------------------------------
[gpc-cpp]
C_INCLUDE_PATH=%/>;C_INCLUDE_PATH%%DJDIR%/lang/pascal;%DJDIR%/include;%DJDIR%/contrib/grx20/include
[gpc]
COMPILER_PATH=%/>;COMPILER_PATH%%DJDIR%/bin
LIBRARY_PATH=%/>;LIBRARY_PATH%%DJDIR%/lib;%DJDIR%/contrib/grx20/lib
---------------------------------------------------------
The binary distribution should come with a `djgpp.env' which is
already modified, so you may not have to do this.
Specific information for low-memory conditions and more can be found
in the djgpp FAQ and documentation.
GPC says: no DPMI
=================
You don't have a DPMI server installed, and DJGPP v2 requires it to
run. You can either use one of the commercial DPMI servers (e.g., run
`gpc' in a DOS box under Windows) or download and install CWSDPMI
(`csdpmi3b.zip') which is a free DPMI server written for DJGPP.
I cannot read the info pages!
=============================
To read the info pages, you need the `info' program from txi360b.zip.
At least for some of the pre-releases of gpc-1.2, the gpc.info file is
invalid: it refers to the "gpc.i*" sections as "gpc.info-*". This can be
fixed by loading gpc.inf in an editor and replacing "gpc.info-*" with
"gpc.i*"
I have troubles with assembly code
==================================
The GNU Assembler (`as.exe'), or `gas', called by GCC accepts "AT&T"
syntax which is different from "Intel" syntax. Differences are
discussed in section 17.1 of the djgpp FAQ.
A guide is available which was written by Brennan Mr. Wacko Underwood
and describes how to use inline assembly
programming with DJGPP, at this URL:
http://www.rt66.com/~brennan/djgpp/djgpp_asm.html
Section 17.3 of the djgpp FAQ discusses some methods to convert
"Intel" syntax to "AT&T".
Tell me how to do DPMI, BIOS and other DOS related things.
==========================================================
DPMI, BIOS and other functions are no different than other system
functions. Refer to section 3.1 how to access your system's C-library.
This small example shows how to use DPMI, copying some structures and
function prototypes of :
---------------------------------------------------------
program dpmitest;
{$X+}
type
word = __unsigned__ integer;
short = __short__ integer;
byte = __byte__ integer;
type
PDpmiVersionRet = ^TDpmiVersionRet;
TDpmiVersionRet = record
major : byte;
minor : byte;
flags : short;
cpu : byte;
master_pic : byte;
slave_pic : byte;
end;
type
PDpmiFreeMemInfo = ^TDpmiFreeMemInfo;
TDpmiFreeMemInfo = record
largest_available_free_block_in_bytes : word;
maximum_unlocked_page_allocation_in_pages : word;
maximum_locked_page_allocation_in_pages : word;
linear_address_space_size_in_pages : word;
total_number_of_unlocked_pages : word;
total_number_of_free_pages : word;
total_number_of_physical_pages : word;
free_linear_address_space_in_pages : word;
size_of_paging_file_partition_in_pages : word;
reserved1 : byte;
reserved2 : byte;
reserved3 : byte;
end;
function DpmiGetVersion(ret: PDpmiVersionRet): integer;
asmname '__dpmi_get_version';
function DpmiGetFreeMemoryInformation(info: PDpmiFreeMemInfo): integer;
asmname '__dpmi_get_free_memory_information';
var
version: TDpmiVersionRet;
meminfo: TDpmiFreeMemInfo;
begin
DpmiGetVersion(@version);
writeln('CPU type : ', version.cpu, '86');
writeln('DPMI major : ', version.major);
writeln('DPMI minor : ', version.minor);
DpmiGetFreeMemoryInformation(@meminfo);
writeln('Free DPMI memory : ', meminfo.total_number_of_free_pages, ' pages.');
end.
---------------------------------------------------------
I'm accessing an "array[1..4000000] of byte" and I got an exception.
====================================================================
Per default, the maximum stack size of a djgpp application is 256K.
If you need more, you have to adjust it with the stubedit program, i.e.:
stubedit your_app.exe minstack=5000K
Still, it might be a good idea to use pointers for this kind of
structures, and allocate the memory at runtime.
Getting Help
************
This section discusses ways to get help with GNU Pascal. Please read
the documentation (info files, readme's) that come with GPC, plus other
docs that might help (the djgpp FAQ if you use djgpp etc.) before you
send email to the maintainers or mailing list.
Help! the compiler crashed!
===========================
If the compiler crashes, you have discovered a bug. A reliable
compiler never crashes. To help the maintainers fix this bug, it is
important that you send us a problem report.
I think I found a bug - now what?
=================================
Bugs are best reported to the GPC mailinglist, gpc@hut.fi. That
way, they always reach the maintainers. Try to give as much information
as possible, plus a short code snippet that triggers the compiler bug.
If you're on unix, you can find out where the compiler crashed if you
enable coredumps, then load the compiler (gpc1) plus the core file in
the debugger ("gdb /your_path_here/gpc1 core"), then type `backtrace'
to get a stacktrace. Include this stacktrace in your bug report.
Which newsgroup(s) are suited for GPC related problems?
=======================================================
There are several Pascal related newsgroups, but none is dedicated
just to GNU Pascal. This one may be useful:
comp.lang.pascal.misc Pascal in general and ungrouped Pascals.
Pascal syntax related questions may be appropriate in:
comp.lang.pascal.ansi-iso Pascal according to ANSI and ISO standards.
comp.lang.pascal.borland Borland Pascal questions.
How to post to the mailing list
===============================
You can send a message to the GPC mailing list by sending email to
the list address as if it were a person.
How to become a subscriber to the mailing list
==============================================
You can join the mailing list by sending a message to
(NOT !) with your request to be added
to the list. Maintenance is done by hand, so some delay is possible.
How to unsubscribe from the mailing list
========================================
To leave the mailing list, send a message to .
Miscellaneous
*************
I want to contribute; where do I start?
=======================================
A list of jobs which should be done for GNU-Pascal can be found in
the section "How to contribute of the Texinfo deocumentation. In cases
where somebody is already working on a topic, the name of that person
is written behind the job's description.
This does not mean that you shouldn't do that but just that you
should get in contact with that person if you would like to contribute
to that field.
About this FAQ.
===============
Maintainer: J.J. van der Heijden
This is the first incarnation of the GNU Pascal FAQ list. Comments
about, suggestions for, or corrections to this FAQ list are welcome.
Please make sure to include in your mail the version number of the
document to which your comments apply (you can find the version at the
beginning of this FAQ list).
Much of the info in this FAQ list was taken from the gpc mailing
list traffic, so you may have (unbeknownst to you) contributed to this
list.
---
"Nothing shocks me, I'm a scientist", Indiana Jones
J.J. van der Heijden (j.j.vanderheijden@student.utwente.nl)
HTML conversion by Lluís de Yzaguirre i Maura
Institut de Lingüística Aplicada -
Universitat "Pompeu Fabra"
e-mail: de_yza@upf.es