Free Pascal :
Users' manual
Users' manual for Free Pascal, version 0.99.12
1.6
July 1999
Micha¨el Van Canneyt
Florian Kl¨ampfl
Contents
1 Introduction 4
1.1 About this document . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 About the compiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Getting more information. . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Installing the compiler 6
2.1 Before Installation : Requirements . . . . . . . . . . . . . . . . . . . 6
System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Software requirements . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Installing the compiler. . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Installing under DOS . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Installing under Linux . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Optional configuration steps . . . . . . . . . . . . . . . . . . . . . . . 10
2.4 Testing the compiler . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 Compiler usage 12
3.1 File searching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Command line files . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Unit files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Include files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Object files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Configuration file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4 Compiling a program . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.5 Compiling a unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.6 Creating an executable for GO32V1 and PMODE/DJ targets . . . . 16
GO32V1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
PMODE/DJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.7 Reducing the size of your program . . . . . . . . . . . . . . . . . . . 17
4 Compiling problems 18
4.1 General problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.2 Problems you may encounter under DOS . . . . . . . . . . . . . . . 18
1
CONTENTS
5 Compiler configuration 19
5.1 Using the command-line options . . . . . . . . . . . . . . . . . . . . 19
General options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Options for getting feedback . . . . . . . . . . . . . . . . . . . . . . . 20
Options concerning files and directories . . . . . . . . . . . . . . . . 20
Options controlling the kind of output. . . . . . . . . . . . . . . . . . 21
Options concerning the sources (language options) . . . . . . . . . . 23
5.2 Using the configuration file . . . . . . . . . . . . . . . . . . . . . . . 24
#IFDEF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
#IFNDEF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
#ELSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
#ENDIF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
#DEFINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
#UNDEF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
#WRITE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
#INCLUDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
#SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.3 Variable substitution in paths . . . . . . . . . . . . . . . . . . . . . . 28
6 Porting Turbo Pascal Code 29
6.1 Things that will not work . . . . . . . . . . . . . . . . . . . . . . . . 29
6.2 Things which are extra . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.3 Turbo Pascal compatibility mode . . . . . . . . . . . . . . . . . . . . 32
7 Utilities and units that come with Free Pascal 34
7.1 Supplied programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
ppudump program . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Demo programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Documentation Example programs . . . . . . . . . . . . . . . . . . . 35
ppumove program . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
ptop - Pascal source beautifier . . . . . . . . . . . . . . . . . . . . . . 36
7.2 Supplied units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Under DOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Under Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
8 Debugging your Programs 42
8.1 Compiling your program with debugger support . . . . . . . . . . . . 42
8.2 Using gdb to debug your program . . . . . . . . . . . . . . . . . . . . 43
8.3 Caveats when debugging with gdb . . . . . . . . . . . . . . . . . . . 44
8.4 Support for gprof, the gnu profiler . . . . . . . . . . . . . . . . . . 45
2
CONTENTS
9 CGI programming in Free Pascal 46
9.1 Getting your data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Data coming through standard input. . . . . . . . . . . . . . . . . . 47
Data passed through an environment variable . . . . . . . . . . . . . 48
9.2 Producing output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
9.3 I'm under Windows, what now ? . . . . . . . . . . . . . . . . . . . . 51
A Alphabetical listing of command-line options 52
B Alphabetical list of reserved words 55
C Compiler messages 56
C.1 General compiler messages . . . . . . . . . . . . . . . . . . . . . . . . 56
C.2 Scanner messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
C.3 Parser messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
C.4 Type checking errors . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
C.5 Symbol handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
C.6 Code generator messages . . . . . . . . . . . . . . . . . . . . . . . . . 74
C.7 Unit loading messages. . . . . . . . . . . . . . . . . . . . . . . . . . . 76
C.8 Command-line handling errors . . . . . . . . . . . . . . . . . . . . . 78
C.9 Assembler reader errors. . . . . . . . . . . . . . . . . . . . . . . . . . 79
General assembler errors . . . . . . . . . . . . . . . . . . . . . . . . . 79
I386 specific errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
m68k specific errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
D Run time errors 85
E The Floating Point Coprocessor emulator 88
F A sample gdb.ini file 90
3
Chapter 1
Introduction
1.1 About this document
This is the user's manual for Free Pascal. It describes the installation and use of
the Free Pascal compiler on the di erent supported platforms. It does not attempt
to give an exhaustive list of all supported commands, nor a definition of the Pascal
language. Look at the Reference guide for these things. For a description of the
possibilities and the inner workings of the compiler, see the Programmers' guide. In
the appendices of this document you will find lists of reserved words and compiler
error messages (with descriptions).
This document describes the compiler as it is/functions at the time of writing. Since
the compiler is under continuous development, some of the things described here
may be outdated. In case of doubt, consult the README files, distributed with the
compiler. The README files are, in case of conflict with this manual, authoritative.
1.2 About the compiler
Free Pascal is a 32-bit compiler for the i386 and m68k processors1. Currently, it
supports 6 operating systems:
* dos
* linux
* Atari (version 0.99.5 only)
* Amiga (version 0.99.5 only)
* Windows NT
* os/2 (using the EMX package, so it also works on DOS/Windows)
and work is in progress to port it to other platforms (notably, FreeBSD).
Free Pascal is designed to be, as much as possible, source compatible with Turbo
Pascal 7.0 and Delphi 4 (although this goal is not yet attained), but it also en-
hances these languages with elements like function overloading. And, unlike these
ancestors, it supports multiple platforms.
1Work is being done on a port to ALPHA Architecture
4
1.3. GETTING MORE INFORMATION.
It also di ers from them in the sense that you cannot use compiled units from one
system for the other.
Also, at the time of writing, there is no Integrated Development Environment (IDE)
available for Free Pascal. This gap will, hopefully, be filled in the future.
Free Pascal consists of three parts :
1. The compiler program itself.
2. The Run-Time Library (RTL).
3. Utility programs and units.
Of these you only need the first two, in order to be able to use the compiler. In
this document, we describe the use of the compiler. The RTL is described in the
Reference guide.
1.3 Getting more information.
If the documentation doesn't give an answer to your questions, you can obtain more
information on the Internet, on the following addresses:
* http://tfdec1.fys.kuleuven.ac.be/ michael/fpc/fpc.html is the main site. It
contains also useful mail addresses and links to other places. It also contains
the instructions for inscribing to the mailing-list.
* http://www.brain.uni-freiburg.de/ klaus/fpc/fpc.html is a mirror of the main
Free Pascal information site.
Both places can be used to download the Free Pascal distribution, although you
can probably find them on other places also.
Finally, if you think something should be added to this manual (entirely possible),
please do not hesitate and contact me at michael@tfdec1.fys.kuleuven.ac.be .
Let's get on with something useful.
5
Chapter 2
Installing the compiler
2.1 Before Installation : Requirements
System requirements
The compiler needs at least the following hardware:
1. An I386 or higher processor. A coprocessor is not required, although it will
slow down your program's performance if you do floating point calculations.
2. 2 Mb of free memory. Under dos, if you use DPMI memory management,
such as under Windows, you will need at least 16 Mb.
3. At least 500 Kb. free disk space.
Software requirements
Under DOS
The dos distribution contains all the files you need to run the compiler and compile
pascal programs.
Under Linux
Under linux you need to have the following programs installed :
1. gnu as, the gnu assembler.
2. gnu ld, the gnu linker.
3. Optionally (but highly recommended) : gnu make. For easy recompiling of
the compiler and Run-Time Library, this is needed.
Other than that, Free Pascal should run on almost any I386 linux system.
2.2 Installing the compiler.
The installation of Free Pascal is easy, but is platform-dependent. We discuss the
process for each platform separately.
6
2.2. INSTALLING THE COMPILER.
Installing under DOS
Mandatory installation steps.
First, you must get the latest distribution files of Free Pascal. They come as zip
files, which you must unzip first, or you can download the compiler as a series
of separate files. This is especially useful if you have a slow connection, but it is
also nice if you want to install only some pats of the compiler distribution. The
distribution zip file contains an installation program INSTALL.EXE. You must run
this program to install the compiler.
The screen of the installation program looks like figure 2.1.
The program allows you to select:
* What components you wish to install. e.g do you want the sources or not, do
you want docs or not. Items that you didn't download when downloading as
separate files, will not be enabled, i.e. you can't select them.
* Where you want to install (the default location is C:\PP).
In order to run Free Pascal from any directory on your system, you must extend
your path variable to contain the C:\PP\BIN directory. Usually this is done in the
AUTOEXEC.BAT file. It should look something like this :
SET PATH=%PATH%;C:\PP\BIN
(Again, assuming that you installed in the default location).
If you want to use the graphic drivers you must modify the environment variable
GO32. Instructions for doing this can be found in the documentation of the Graph
unit, at the InitGraph procedure.
Optional Installation: The coprocessor emulation
For people who have an older CPU type, without math coprocessor (i387) it is
necessary to install a coprocessor emulation, since Free Pascal uses the coprocessor
to do all floating point operations.
The installation of the coprocessor emulation is handled by the installation program
(INSTALL.EXE). However,
Installing under Linux
Mandatory installation steps.
The linux distribution of Free Pascal comes in three forms:
* a tar.gz version, also available as seperate files.
* a .rpm (Red Hat Package Manager) version, and
* a .deb (debian) version.
All of these packages contain a ELF version of the compiler binaries and units. the
older aout binaries are no longer distributed, although you still can use the comiler
on an aout system if you recompile it.
If you use the .rpm format, installation is limited to
7
2.2. INSTALLING THE COMPILER.
Figure 2.1: The dos install program screen.
8
2.2. INSTALLING THE COMPILER.
rpm -i fpc-pascal-XXX.rpm
(XXX is the version number of the .rpm file)
If you use debian, installation is limited to
dpkg -i fpc-XXX.deb
Here again, XXX is the version number of the .deb file.
You need root access to install these packages. The .tar file allows you to do an
installation if you don't have root permissions.
When downloading the .tar file, or the separate files, installation is more interac-
tive.
In case you downloaded the .tar file, you should first untar the file, in some directory
where you have write permission, using the following command:
tar -xvf fpc.tar
We supposed here that you downloaded the file fpc.tar somewhere from the Internet.
(The real filename will have some version number in it, which we omit here for
clarity.)
When the file is untarred, you will be left with more archive files, and an install
program: an installation shell script.
If you downloaded the files as separate files, you should at least download the
install.sh script, and the libraries (in libs.tar.gz).
To install Free Pascal, all that you need to do now is give the following command:
./install.sh
And then you must answer some questions. They're very simple, they're mainly
concerned with 2 things :
1. Places where you can install di erent things.
2. Deciding if you want to install certain components (such as sources and demo
programs).
The script will automatically detect which components are present and can be
installed. It will only o er to install what has been found. because of this feature,
you must keep the original names when downloading, since the script expects this.
If you run the installation script as the root user, you can just accept all installation
defaults. If you don't run as root, you must take care to supply the installation
program with directory names where you have write permission, as it will attempt
to create the directories you specify. In principle, you can install it wherever you
want, though.
At the end of installation, the installation program will generate a configuration
file for the Free Pascal compiler which reflects the settings that you chose. It will
install this file in the /etc directory, (if you are not installing as root, this will fail),
and in the directory where you installed the libraries.
If you want the Free Pascal compiler to use this configuration file, it must be present
in /etc, or you can set the environment variable PPC CONFIG PATH. Under csh, you
can do this by adding a
9
2.3. OPTIONAL CONFIGURATION STEPS
setenv PPC_CONFIG_PATH /usr/lib/ppc/0.99.1
line to your .login file in your home directory. (see also the next section)
2.3 Optional configuration steps
You may wish to set some environment variables. The Free Pascal compiler recog-
nizes the following variables :
* PPC_EXEC_PATH contains the directory where 'as' and 'ld' are. (default /usr/bin)
* PPC_GCCLIB_PATH contains the directory where libgcc.a is (no default). This
if for linux only.
* PPC_CONFIG_PATH specifies an alternate path to find ppc386.cfg (default under
linux is /etc)
* PPC_ERROR_FILE specifies the path and name of the error-definition file. (de-
fault /usr/lib/fpc/errorE.msg)
These locations are, however, set in the sample configuration file which is built at
the end of the installation process, except for the PPC_CONFIG_PATH variable, which
you must set if you didn't install things in the default places.
finally
Also distributed in Free Pascal is a README file. It contains the latest instructions
for installing Free Pascal, and should always be read first.
2.4 Testing the compiler
After the installation is completed and the environment variables are set as described
above, your first program can be compiled.
Included in the Free Pascal distribution are some demonstration programs, showing
what the compiler can do. You can test if the compiler functions correctly by trying
to compile these programs.
The compiler is called
* PPC386.EXE under dos, and
* ppc386 under linux
To compile a program (e.g demo\hello.pp) simply type :
ppc386 hello
at the command prompt. If you don't have a configuration file, then you may need
to tell the compiler where it can find the units, for instance as follows:
ppc386 -Upc:\pp\rtl\dos\go32v2 hello
under dos, and under linux you could type
10
2.4. TESTING THE COMPILER
ppc386 -Up/usr/lib/fpc/0.99.7/linuxunits hello
This is, of course, assuming that you installed under C:\PP or /usr/lib/fpc/0.99.7,
respectively.
If you got no error messages, the compiler has generated an executable called hello
(no extension) under linux, and a file hello.exe under dos.
To execute the program, simply type :
hello
If all went well, you should see the following friendly greeting:
Hello world
In the dos case, this friendly greeting may be preceded by some ugly message from
the GO32 extender program. This unfriendly behavior can be switched o by setting
the GO32 environment variable.
11
Chapter 3
Compiler usage
Here we describe the essentials to compile a program and a unit. We also describe
how to make a stand-alone executable of the compiled program under dos. For
more advanced uses of the compiler, see the section on configuring the compiler,
and the Programmers' guide.
The examples in this section suppose that you have a ppc386.cfg which is set up
correctly, and which contains at least the path setting for the RTL units. In principle
this file is generated by the installation program. You may have to check that it is
in the correct place (see section 5.2 for more information on this).
3.1 File searching
Before you start compiling a program or a series of units, it is important to know
where the compiler looks for its source files and other files. In this section we discuss
this, and we indicate how to influence this.
Remark: The use of slashes (/) and backslashes (\) as directory separators is ir-
relevant, the compiler will convert to whatever character is used on the current
operating system. Examples will be given using slashes, since this avoids problems
on linux.
Command line files
The file that you specify on the command line, such as in
ppc386 foo.pp
will be looked for ONLY in the current directory. If you specify a directory in the
filename, then the compiler will look in that directory:
ppc386 subdir/foo.pp
will look for foo.pp in the subdirectory subdir of the current directory.
Under linux, the name of this file is case sensitive, under other operating systems
(dos, Windows NT, os/2) this is not the case.
12
3.2. INCLUDE FILES
Unit files
When you compile a unit or program that needs other units, the compiler will look
for compiled versions of these units in the following way:
1. It will look in the current directory.
2. It will look in the directory where the compiler binary is. (not under linux)
3. It will look in all the directories specified in the unit search path.
You can add a directory to the unit search path with the -Up or -Fu options (See
??, See 5.1). Every occurrence of one of those options will append a directory to
the unit search path.
On linux, the compiler will first convert the filename of a unit to all-lowercase. This
is necessary, since Pascal is case-independent, and the statements Uses Unit1; or
uses unit1; should have the same e ect. Also, unit names that are longer than
8 characters will first be looked for with their full length. If the unit is not found
with this name, the name will be truncated to 8 characters, and the compiler will
look again in the same directories, but with the truncated name.
For instance, suppose that the file foo.pp needs the unit bar. Then the command
ppc386 -Up.. -Upunits foo.pp
will tell the compiler to look for the unit bar in the following places:
1. In the current directory.
2. In the directory where the compile binary is (not under linux).
3. In the parent directory of the current directory.
4. In the subdirectory units of the current directory
If the compiler finds the unit it needs, it will look for the source file of this unit in
the same directory where it found the unit. If it finds the source of the unit, then
it will compare the file times. If the source file was modified more recent than the
unit file, the compiler will attempt to recompile the unit with this source file.
If the compiler doesn't find a compiled version of the unit, or when the -B option
is specified, then the compiler will look in the same manner for the unit source file,
and attempt to recompile it.
It is recommended to set the unit search path in the configuration file ppc386.cfg.
If you do this, you don't need to specify the unit search path on the command-line
every time you want to compile something.
3.2 Include files
If you include files in your source with the {$I filename} directive, the compiler
will look for it in the following places:
1. It will look in the path specified in the incude file name.
2. It will look in the directory where the current source file is.
13
3.3. OBJECT FILES
3. it will look in all directories specified in the include file search path.
You can add files to the include file search path with the -I (See 5.1) option.
As an example, consider the following include statement in a file units/foo.pp:
{$i ../bar.inc}
Then the following command :
ppc386 -Iincfiles units/foo.pp
will cause the compiler to look in the following directories for bar.inc:
1. the parent directory of the current directory
2. the units subdirectory of the current directory
3. the incfiles directory of the current directory.
3.3 Object files
When you link to object files (using the {$L file.o} directive, the compiler will
look for this file in the same way as it looks for include files:
1. It will look in the path specified in the object file name.
2. It will look in the directory where the current source file is.
3. it will look in all directories specified in the object file search path.
You can add files to the object file search path with the -Fo (See 5.1) option.
Configuration file
Unless you specify the -n (See 5.1) option, the compiler will look for a configuration
file ppc386.cfg in the following places:
* Under linux
1. The current directory.
2. In your home directory, it looks for .ppc386.cfg.
3. The directory specified in the environment variable PPC CONFIG PATH,
and if it's not set under /etc.
* Under all other OSes:
1. The current directory.
2. If it is set, the directory specified in the environment variable. PPC CONFIG PATH.
3. The directory where the compiler is.
14
3.4. COMPILING A PROGRAM
3.4 Compiling a program
Compiling a program is very simple. Assuming that you have a program source in
the file prog.pp, you can compile this with the following command:
ppc386 [options] prog.pp
The square brackets [ ] indicate that what is between them is optional.
If your program file has the .pp or .pas extension, you can omit this on the command
line, e.g. in the previous example you could have typed:
ppc386 [options] prog
If all went well, the compiler will produce an executable, or, for version 1 of the
dos extender, a file which can be converted to an executable.
Unless you are using dos and version 1 of the dos extender, the file you obtained
is the executable. You can execute it straight away, you don't need to do anything
else. Under version 1 of the dos extender, additional processing is required. See
section 3.6 on how to create an executable in this case.
You will notice that there is also another file in your directory, with extensions .o.
This contains the object file for your program. If you compiled a program, you
can delete the object file (.o), but not if you compiled a unit. Then the object file
contains the code of the unit, and will be linked in any program that uses the unit
you compiled, so you shouldn't remove it.
3.5 Compiling a unit
Compiling a unit is not essentially di erent from compiling a program. The di er-
ence is mainly that the linker isn't called in this case.
To compile a unit in the file foo.pp, just type :
ppc386 foo
Recall the remark about file extensions in the previous section.
When all went well, you will be left with 2 (two) unit files:
1. foo.ppu This is the file describing the unit you just compiled.
2. foo.o This file contains the actual code of the unit. This file will eventually
end up in the executables.
Both files are needed if you plan to use the unit for some programs. So don't delete
them. If you want to distribute the unit, you must provide both the .ppu and .o
file. One is useless without the other.
Remark: Under linux, a unit source file must have a lowercase filename. Since
Pascal is case independent, you can specify the names of units in the uses clause in
either case. To get a unique filename, the Free Pascal compiler changes the name
of the unit to all lowercase when looking for unit files.
The compiler produces lowercase files, so your unit will be found, even if your source
file has uppercase letters in it. Only when the compiler tries to recompile the unit,
it will not find your source because of the uppercase letters.
15
3.6. CREATING AN EXECUTABLE FOR GO32V1 AND PMODE/DJ
TARGETS
3.6 Creating an executable for GO32V1 and PMODE/DJ
targets
The GO32V1 platform is o cially no longer supported, so this section is of interest
only to people who wish to make go32V1 binaries anyway.
GO32V1
When compiling under dos, GO32V2 is the default target. However, if you use
go32V1 (using the -TGO32V1 switch), the compilation process leaves you with a file
which you cannot execute right away. There are 2 things you can do when compiling
has finished.
The first thing is to use the dos extender from D.J. Delorie to execute your program
:
go32 prog
This is fine for testing, but if you want to use a program regularly, it would be
easier if you could just type the program name, i.e.
prog
This can be accomplished by making a dos executable of your compiled program.
There two ways to create a dos executable (under dos only):
1. if the GO32.EXE is already installed on the computers where the program
should run, you must only copy a program called STUB.EXE at the begin
of the AOUT file. This is accomplished with the AOUT2EXE.EXE program.
which comes with the compiler:
AOUT2EXE PROG
and you get a dos executable which loads the GO32.EXE automatically. the
GO32.EXE executable must be in current directory or be in a directory in the
PATH variable.
2. The second way to create a dos executable is to put GO32.EXE at the begin-
ning of the AOUT file. To do this, at the command prompt, type :
COPY /B GO32.EXE+PROG PROG.EXE
(assuming Free Pascal created a file called PROG, of course.) This becomes
then a stand-alone executable for dos, which doesn't need the GO32.EXE on
the machine where it should run.
PMODE/DJ
You can also use the PMODE/DJ extender to run your Free Pascal applications. To
make an executable which works with the PMODE extender, you can simply create
an GO32V2 executable (the default), and then convert it to a PMODE executable
with the following two extra commands:
1. First, strip the GO32V2 header of the executable:
16
3.7. REDUCING THE SIZE OF YOUR PROGRAM
EXE2COFF PROG.EXE
(we suppose that PROG.EXE is the program generated by the compilation
process.
2. Secondly, add the PMODE stub:
COPY /B PMODSTUB.EXE+PROG PROG.EXE
If the PMODSTUB.EXE file isn't in your local directory, you need to supply
the whole path to it.
That's it. No additional steps are needed to create a PMODE extender executable.
Be aware, though, that the PMODE extender doesn't support virtual memory, so
if you're short on memory, you may run unto trouble. Also, o cially there is not
support for the PMODE/DJ extender. It just happens that the compiler and some
of the programs it generates, run under this extender too.
3.7 Reducing the size of your program
When you created your program, it is possible to reduce its size. This is possible,
because the compiler leaves a lot of information in the program which, strictly
speaking, isn't required for the execution of it. The surplus of information can be
removed with a small program called strip. It comes with the GO32 development
environment under dos, and is standard on linux machines where you can do
development. The usage is simple. Just type
strip prog
On the command line, and the strip program will remove all unnecessary information
from your program. This can lead to size reductions of up to 30 %.
remark: in the Win32 32 version, strip is called stripw
You can use the -Xs switch to let the compiler do this stripping automatically at
program compile time (the switch has no e ect when compiling units).
Another technique to reduce the size of a program is to use smartlinking. Normally,
units (including the system unit) are linked in as a whole. It is however possible to
compile units such that the can be smartlinked. This means that only the functions
and procedures are linked in your program, leaving out any unnecessary code. This
technique is described in full in the programmers guide.
17
Chapter 4
Compiling problems
4.1 General problems
* IO-error -2 at ... : Under linux you can get this message at compiler
startup. It means typically that the compiler doesn't find the error definitions
file. You can correct this mistake with the -Fr option under linux. (See 5.1)
* Error : File not found : xxx or Error: couldn't compile unit xxx:
This typically happens when your unit path isn't set correctly. Remember
that the compiler looks for units only in the current directory, and in the
directory where the compiler itself is. If you want it to look somewhere else
too, you must explicitly tell it to do so using the -Up option (See ??). Or you
must set op a configuration file.
4.2 Problems you may encounter under DOS
* No space in environment.
An error message like this can occur, if you call SET_PP.BAT in the AU-
TOEXEC.BAT.
To solve this problem, you must extend your environment memory. To do
this, search a line in the CONFIG.SYS like
SHELL=C:\DOS\COMMAND.COM
and change it to the following:
SHELL=C:\DOS\COMMAND.COM /E:1024
You may just need to specify a higher value, if this parameter is already set.
* Coprocessor missing
If the compiler writes a message that there is no coprocessor, install the co-
processor emulation.
* Not enough DPMI memory
If you want to use the compiler with DPMI you must have at least 7-8 MB free
DPMI memory, but 16 Mb is a more realistic amount.
18
Chapter 5
Compiler configuration
The output of the compiler can be controlled in many ways. This can be done
essentially in two distinct ways:
* Using command-line options.
* Using the configuration file: ppc386.cfg.
The compiler first reads the configuration file. Only then the command line options
are checked. This creates the possibility to set some basic options in the configura-
tion file, and at the same time you can still set some specific options when compiling
some unit or program. First we list the command line options, and then we explain
how to specify the command line options in the configuration file. When reading
this, keep in mind that the options are case sensitive. While this is customary for
linux, it isn't under dos.
5.1 Using the command-line options
The available options for version 0.99.10 of the compiler are listed by category (see
appendix A for a listing as generated by the compiler):
General options
-h if you specify this option, the compiler outputs a list of all options, and exits
after that.
-? idem as -h, waiting after every screenfull for the enter key.
-i This option tells the compiler to print the copyright information. You can give
it an option, as -ixxx where xxx can be one of the following:
D : Returns the compiler date.
V : Returns the compiler version.
SO : Returns the compiler OS.
SP : Returns the compiler processor.
TO : Returns the target OS.
TP : Returns the target Processor.
19
5.1. USING THE COMMAND-LINE OPTIONS
-l This option tells the compiler to print the Free Pascal logo on standard output.
It also gives you the Free Pascal version number.
-n Tells the compiler not to read default the configuration file. You can still pass
a configuration file with the @ option.
Options for getting feedback
-vxxx Be verbose. xxx is a combination of the following :
* e : Tells the compiler to show only errors. This option is on by default.
* i : Tells the compiler to show some general information.
* w : Tells the compiler to issue warnings.
* n : Tells the compiler to issue notes.
* h : Tells the compiler to issue hints.
* l : Tells the compiler to show the line numbers as it processes a file.
Numbers are shown per 100.
* u : Tells the compiler to print the names of the files it opens.
* t : Tells the compiler to print the names of the files it tries to open.
* p : Tells the compiler to print the names of procedures and functions as
it is processing them.
* c : Tells the compiler to warn you when it processes a conditional.
* m : Tells the compiler to write which macros are defined.
* d : Tells the compiler to write other debugging info.
* a : Tells the compiler to write all possible info. (this is the same as
specifying all options)
* 0 : Tells the compiler to write no messages. This is useful when you
want to override the default setting in the configuration file.
* b : Tells the compiler to show all procedure declarations if an overloaded
function error occurs.
* x : Tells the compiler to output some executable info (for Win32 platform
only).
* r : Rhide/GCC compatibility mode: formats the errors di erently, so
they are understood by RHIDE.
Options concerning files and directories
-exxx xxx specifies the directory where the compiler can find the executables as
(the assembler) and ld (the compiler).
-FD same as -e.
-Fexxx This option tells the compiler to write errors, etc. to the file in xxx.
-Flxxx Adds xxx to the library searching path, and is passed to the linker.
-FLxxx (linux only) Tells the compiler to use xxx as the dynamic linker. Default
this is /lib/ld-linux.so.2, or lib/ld-linux.so.1, depending on which one is found
first.
20
5.1. USING THE COMMAND-LINE OPTIONS
-Foxxx Adds xxx to the object file path. This path is used when looking for files
that need to be linked in.
-Frxxx xxx specifies the file which contain the compiler messages. Default the
compiler ahs built-in messages. Specifying this option will override the default
messages.
-Fuxxx Add xxx to the unit path. Units are loaded from the current directory if
they exist, and then in the unit path. You must always supply the unit path
to the system unit.
-FUxxx Tells the compiler to write units in directory xxx instead of the current
directory.
-Ixxx Add xxx to the include file search path. This path is used when looking for
include files. This option is obsolite, use -Fi instead.
-P uses pipes instead of files when assembling. This may speed up the compiler
on os/2 and linux. Only with assemblers (such as gnu as) that support
piping...
Options controlling the kind of output.
for more information on these options, see also Programmers' guide
-a Tells the compiler not to delete the assembler files it generates (not when using
the internal assembler). This also counts for the (possibly) generated batch
script.
-al Tells the compiler to include the sourcecode lines in the assembler file as com-
ments. This feature is still experimental, and should be used with caution.
-ar tells the compiler to list register allocation and release info in the assembler file.
This is primarily intended for debugging the code generated bythe compiler.
-at tells the compiler to list information about temporary allocations and deallo-
cations in the assembler file.
-Axxx specifies what kind of assembler should be generated . Here xxx is one of
the following :
* o : A unix co object file, using the gnu assembler as.
* nasmco : a co file using the nasm assembler.
* nasmelf : a ELF32 file (linux only) using the nasm assembler.
* nasmonj : a obj file using the nasm assembler.
* masm : An obj file using the Microsoft masm assembler.
* tasm : An obj file using the Borland tasm assembler.
-B tells the compiler to re-compile all used units, even if the unit sources didn't
change since the last compilation.
-b tells the compiler to generate browser info. This information can be used by
an Integrated Development Environment (IDE) to provide information on
classes, objects, procedures, types and variables in a unit.
-bl is the same as -b but also generates information about local variables, types
and procedures.
21
5.1. USING THE COMMAND-LINE OPTIONS
-CD Create a dynamic library. This is used to transform units into dynamically
linkable libraries on linux.
-Chxxx Reserves xxx bytes heap. xxx should be between 1024 and 67107840.
-Ci Generate Input/Output checking code. In case some input/output code of your
program returns an error status, the program will exit with a run-time error.
Which error is generated depends on the I/O error.
-Cn Omit the linking stage.
-Co Generate Integer overflow checking code. In case of integer errors, a run-time
error will be generated by your program.
-Cr Generate Range checking code. In case your program acesses an array element
with an invalid index, or if it increases an enumerated type beyond it's scope,
a run-time error will be generated.
-Csxxx Set stack size to xxx.
-CS Create static library.
-Ct generate stack checking code. In case your program performs a faulty stack
operation, a run-rime error will be generated.
-Cx Use smartlinking when compiling and linking units. smartlinking will only
link in the code parts that are actually needed by the program. All unused
code is left out. This can lead to substantially smaller binaries.
-dxxx Define the symbol name xxx. This can be used to conditionally compile
parts of your code.
-E Same as -Cn.
-g Generate debugging information for debugging with gdb
-gg idem as -g.
-gd generate debugging info for dbx.
-gh use the heaptrc unit (see Unit reference).
-Oxxx optimize the compiler's output; xxx can have one of the following values :
g optimize for size, try to generate smaller code.
G optimize for time, try to generate faster code (default).
r keep certain variables in registers (experimental, use with caution).
u Uncertain optimizations
1 Level 1 optimizations (quick optimizations).
2 Level 2 optimizations (-O1 plus some slower optimizations).
3 Level 3 optimizations (-O2 plus -Ou).
Pn (Intel only) Specify processor: n can be one of
1 optimize for 386/486
2 optimize for Pentium/PentiumMMX (tm)
3 optimizations for PentiumPro/PII/Cyrix 6x86/K6 (tm)
The exact e ect of these e ects can be found in the Programmers' guide.
22
5.1. USING THE COMMAND-LINE OPTIONS
-oxxx Tells the compiler to use xxx as the name of the output file (executable).
Only with programs.
-pg Generate profiler code for gprof.
-s Tells the compiler not to call the assembler and linker. Instead, the compiler
writes a script, PPAS.BAT under dos, or ppas.sh under linux, which can
then be executed to produce an executable. This can be used to speed up the
compiling process or to debug the compiler's output.
-Txxx Specifies the target operating system. xxx can be one of the following:
* GO32V1 : dos and version 1 of the DJ DELORIE extender (no longer
maintained).
* GO32V2 : dos and version 2 of the DJ DELORIE extender.
* LINUX : linux.
* OS2 : OS/2 (2.x) using the EMX extender.
* WIN32 : Windows 32 bit.
-uxxx undefine the symbol xxx. This is the opposite of the -d option.
-uxxx Undefine symbol xxx.
-Xx executable options. This tells the compiler what kind of executable should be
generated. the parameter x can be one of the following:
* c : (linux only) Link with the C library. You should only use this when
you start to port Free Pascal to another operating system.
* D : Link with dynamic libraries (defines the FPC LINK DYNAMIC symbol)
* s : Strip the symbols from the executable.
* S : Link with static libraries (defines the FPC LINK STATIC symbol)
Options concerning the sources (language options)
for more information on these options, see also Programmers' guide
-Rxxx Specifies what kind of assembler you use in your asm assembler code blocks.
Here xxx is one of the following:
att asm blocks contain AT&T-style assembler. This is the default style.
intel asm blocks contain Intel-style assembler.
direct asm blocks should be copied as-is in the assembler, only replacing
certain variables. file.
-S2 Switch on Delphi 2 extensions. This is di erent from -Sd because some Free
Pascal constructs are still available to you.
-Sc Support C-style operators, i.e. *=, +=, /= and -=.
-Sd Tells the compiler to be Delphi compatible. This is more strict than the -S2
option, since some fpc extensions are switched o .
-Se The compiler stops after the first error. Normally, the compiler tries to continue
compiling after an error, until 50 errors are reached, or a fatal error is reached,
and then it stops. With this switch, the compiler will stop after the first error.
23
5.2. USING THE CONFIGURATION FILE
-Sg Support the label and goto commands. By default these are not supported.
You must also specify this option if you use labels in assembler statements.
(if you use the AT&T style assember)
-Sh Use ansistrings by default for strings. If this keyword is specified, the compiler
will interpret the string keyword as a ansistring. Otherwise it is supposed
to be a short strings (TP style).
-Si Support C++ style INLINE.
-Sm Support C-style macros.
-So Try to be Borland TP 7.0 compatible (no function overloading etc.).
-Sp Try to be gpc (gnu pascal compiler) compatible.
-Ss The name of constructors must be init, and the name of destructors should
be done.
-St Allow the static keyword in objects.
-Un Do not check the unit name. Normally, the unit name is the same as the
filename. This option allows both to be di erent.
-Us Compile a system unit. This option causes the compiler to define only some
very basic types.
5.2 Using the configuration file
Using the configuration file ppc386.cfg is an alternative to command line options.
When a configuration file is found, it is read, and the lines in it are treated like you
typed them on the command line. They are treated before the options that you
type on the command line.
You can specify comments in the configuration file with the # sign. Everything from
the # on will be ignored.
The compiler looks for the ppc386.cfg file in the following places :
* Under linux
1. The current directory.
2. In your home directory, it looks for .ppc386.cfg.
3. The directory specified in the environment variable PPC CONFIG PATH,
and if it's not set under /etc.
* Under all other OSes:
1. The current directory.
2. If it is set, the directory specified in the environment variable. PPC CONFIG PATH.
3. The directory where the compiler is.
When the compiler has finished reading the configuration file, it continues to treat
the command line options.
One of the command-line options allows you to specify a second configuration file:
Specifying @foo on the command line will open file foo, and read further options
24
5.2. USING THE CONFIGURATION FILE
from there. When the compiler has finished reading this file, it continues to process
the command line.
The configuration file allows some kind of preprocessing. It understands the follow-
ing directives, which you should place on the first column of a line :
#IFDEF
#IFNDEF
#ELSE
#ENDIF
#DEFINE
#UNDEF
#WRITE
#INCLUDE
#SECTION
They work the same way as their {$...} counterparts in Pascal.
What follows is a description of the di erent directives.
#IFDEF
Syntax:
#IFDEF name
Lines following #IFDEF are skipped read if the keyword name following it is not
defined.
They are read until the keywords #ELSE or #ENDIF are encountered, after which
normal processing is resumed.
Example :
#IFDEF VER0_99_5
-Up/usr/lib/fpc/0.99.5/linuxunits
#ENDIF
In the above example, /usr/lib/fpc/0.99.5/linuxunits will be added to the path if
you're compiling with version 0.99.5 of the compiler.
#IFNDEF
Syntax:
#IFNDEF name
Lines following #IFDEF are skipped read if the keyword name following it is defined.
They are read until the keywords #ELSE or #ENDIF are encountered, after which
normal processing is resumed.
Example :
25
5.2. USING THE CONFIGURATION FILE
#IFNDEF VER0_99_5
-Up/usr/lib/fpc/0.99.6/linuxunits
#ENDIF
In the above example, /usr/lib/fpc/0.99.6/linuxunits will be added to the path if
you're NOT compiling with version 0.99.5 of the compiler.
#ELSE
Syntax:
#ELSE
#ELSE can be specified after a #IFDEF or #IFNDEF directive as an alternative. Lines
following #ELSE are skipped read if the preceding #IFDEF #IFNDEF was accepted.
They are skipped until the keyword #ENDIF is encountered, after which normal
processing is resumed.
Example :
#IFDEF VER0_99_5
-Up/usr/lib/fpc/0.99.6/linuxunits
#ELSE
-Up/usr/lib/fpc/0.99.5/linuxunits
#ENDIF
In the above example, /usr/lib/fpc/0.99.5/linuxunits will be added to the path if
you're compiling with version 0.99.5 of the compiler, otherwise /usr/lib/fpc/0.99.6/linuxunits
will be added to the path.
#ENDIF
Syntax:
#ENDIF
#ENDIF marks the end of a block that started with #IF(N)DEF, possibly with an
#ELSE between it.
#DEFINE
Syntax:
#DEFINE name
#DEFINE defines a new keyword. This has the same e ect as a -dname command-line
option.
#UNDEF
Syntax:
#UNDEF name
#UNDEF un-defines a keyword if it existed. This has the same e ect as a -uname
command-line option.
26
5.2. USING THE CONFIGURATION FILE
#WRITE
Syntax:
#WRITE Message Text
#WRITE writes Message Text to the screen. This can be useful to display warnings
if certain options are set.
Example:
#IFDEF DEBUG
#WRITE Setting debugging ON...
-g
#ENDIF
if DEBUG is defined, this will produce a line
Setting debugging ON...
and will then switch on debugging information in the compiler.
#INCLUDE
Syntax:
#INCLUDE filename
#INCLUDE instructs the compiler to read the contents of filename before continuing
to process options in the current file.
This can be useful if you want to have a particular configuration file for a project
(or, under linux, in your home directory), but still want to have the global options
that are set in a global configuration file.
Example:
#IFDEF LINUX
#INCLUDE /etc/ppc386.cfg
#ELSE
#IFDEF GO32V2
#INCLUDE c:\pp\bin\ppc386.cfg
#ENDIF
#ENDIF
This will include /etc/ppc386.cfg if you're on a linux machine, and will include
c:\pp\bin\ppc386.cfg on a dos machine.
#SECTION
Syntax:
#SECTION name
The #SECTION directive acts as a #IFDEF directive, only it doesn't require an #ENDIF
directive. the special name COMMON always exists, i.e. lines following #SECTION
COMMON are always read.
27
5.3. VARIABLE SUBSTITUTION IN PATHS
5.3 Variable substitution in paths
To avoid having to edit your configuration files too often, the compiler allows you
to specify the following variables in the paths that you feed to the compiler:
FPCVER is replaced by the compiler's full version string.
FPCDATE is replaced by the compiler's date.
FPCTARGET is replaced by the compiler's target CPU (deprecated).
FPCCPU is also replaced by the compiler's target CPU.
TARGET is replaced by the compiler's target OS.(deprecated)
FPCOS is replaced by the compiler's target OS.
To have these variables subsituted, just insert them with a $ prepended, as follows:
-Fu/usr/lib/fpc/$FPCVER/rtl/$FPCOS
This is equivalent to
-Fu/usr/lib/fpc/0.99.12a/rtl/linux
If the compiler version is 0.99.12a and the target os is linux.
These replacemens are valid on the command-line and also in the configuration file.
On the linux command-line, you must be careful to escape the $ since otherwise the
shell will expand the variable for you, which may have undesired e ects.
28
Chapter 6
Porting Turbo Pascal Code
Free Pascal was designed to resemble Turbo Pascal as closely as possible. There
are, of course, restrictions. Some of these are due to the fact that Free Pascal is a
32-bit compiler. Other restrictions result from the fact that Free Pascal works on
more than one operating system.
In general we can say that if you keep your program code close to ANSI Pascal, you
will have no problems porting from Turbo Pascal, or even Delphi, to Free Pascal.
To a large extent, the constructs defined by Turbo Pascal are supported. This is
even more so if you use the -So or -S2 switches.
In the following sections we will list the Turbo Pascal constructs which are not
supported in Free Pascal, and we will list in what ways Free Pascal extends the
Turbo Pascal language.
6.1 Things that will not work
Here we give a list of things which are defined/allowed in Turbo Pascal, but which
are not supported by Free Pascal. Where possible, we indicate the reason.
1. Parameter lists of previously defined functions and procedures must match
exactly. The reason for this is the function overloading mechanism of Free
Pascal. (however, the -So switch solves this. See 5.1)
2. (* ... *) as comment delimiters are not allowed in versions older than
0.9.1. This can easily be remedied with a grown-up editor.
3. The MEM, MEMW, MEML and PORT variables for memory and port access are not
available in the system unit. This is due to the operating system. Under dos,
the extender unit (GO32.PPU) implements the mem constuct. under linux,
the ports unit implements such a construct.
4. PROTECTED, PUBLIC, PUBLISHED, TRY, FINALLY, EXCEPT, RAISE are reserved
words. This means you cannot create procedures or variables with the same
name. While they are not reserved words in Turbo Pascal, they are in Delphi.
Using the -So switch will solve this problem if you want to compile Turbo
Pascal code that uses these words.
5. The reserved words FAR, NEAR are ignored. This is because Free Pascal is a
32 bit compiler, so they're obsolete.
29
6.2. THINGS WHICH ARE EXTRA
6. INTERRUPT only will work on a DOS machine.
7. Boolean expressions are only evaluated until their result is completely deter-
mined. The rest of the expression will be ignored.
8. By default the compiler uses AT&T assembler syntax. This is mainly because
Free Pascal uses gnu as. However other assembler forms are available, Pro-
grammers' guide.
9. Turbo Vision is not available.
10. The 'overlay' unit is not available. It also isn't necessary, since Free Pascal is
a 32 bit compiler, so program size shouldn't be a point.
11. There are more reserved words. (see appendix B for a list of all reserved
words.)
12. The command-line parameters of the compiler are di erent.
13. Compiler switches and directives are mostly the same, but some extra exist.
14. Units are not binary compatible.
6.2 Things which are extra
Here we give a list of things which are possible in Free Pascal, but which didn't
exist in Turbo Pascal or Delphi.
1. There are more reserved words. (see appendix B for a list of all reserved
words.)
2. Functions can also return complex types, such as records and arrays.
3. You can handle function results in the function itself, as a variable. Example
function a : longint;
begin
a:=12;
while a>4 do
begin
{...}
end;
end;
The example above would work with TP, but the compiler would assume that
the a>4 is a recursive call. To do a recursive call in this you must append ()
behind the function name:
function a : longint;
begin
a:=12;
{ this is the recursive call }
if a()>4 then
begin
30
6.2. THINGS WHICH ARE EXTRA
{...}
end;
end;
4. There is partial support of Delphi constructs. (see the Programmers' guide
for more information on this).
5. The exit call accepts a return value for functions.
function a : longint;
begin
a:=12;
if a>4 then
begin
exit(a*67); {function result upon exit is a*67 }
end;
end;
6. Free Pascal supports function overloading. That is, you can define many
functions with the same name, but with di erent arguments. For example:
procedure DoSomething (a : longint);
begin
{...}
end;
procedure DoSomething (a : real);
begin
{...}
end;
You can then call procedure DoSomething with an argument of type Longint
or Real.
This feature has the consequence that a previously declared function must
always be defined with the header completely the same:
procedure x (v : longint); forward;
{...}
procedure x;{ This will overload the previously declared x}
begin
{...}
end;
This construction will generate a compiler error, because the compiler didn't
find a definition of procedure x (v : longint);. Instead you should de-
fine your procedure x as:
procedure x (v : longint);
{ This correctly defines the previously declared x}
begin
{...}
end;
31
6.3. TURBO PASCAL COMPATIBILITY MODE
(The See 5.1 switch disables overloading. When you use it, the above will
compile, as in Turbo Pascal.
7. Operator overloading. Free Pascal allows to overload operators, i.e. you can
define e.g. the '+' operator for matrices.
8. On FAT16 and FAT32 systems, long file names are supported.
6.3 Turbo Pascal compatibility mode
When you compile a program with the -So switch, the compiler will attempt to
mimic the Turbo Pascal compiler in the following ways:
* Assigning a procedural variable doesn't require a @ operator. One of the
di erences between Turbo Pascal and Free Pascal is that the latter requires
you to specify an address operator when assigning a value to a procedural
variable. In Turbo Pascal compatibility mode, this is not required.
* Procedure overloading is disabled. This means that function header and im-
plementation can be di erent (i.e. the function iplementation doesn't need to
repeat the function header).
* Forward defined procedures don't need the full parameter list when they are
defined. Due to the procedure overloading feature of Free Pascal, you must
always specify the parameter list of a function when you define it, even when
it was declared earlier with Forward. In Turbo Pascal compatibility mode,
there is no function overloading, hence you can omit the parameter list:
Procedure a (L : Longint); Forward;
...
Procedure a ; { No need to repeat the (L : Longint) }
begin
...
end;
* recursive function calls are handled d erently. Consider the following example
:
Function expr : Longint;
begin
...
Expr:=L:
Writeln (Expr);
...
end;
In Turbo Pascal compatibility mode, the function will be called recursively
when the writeln statement is processed. In Free Pascal, the function result
will be printed. In order to call the function recusively under Free Pascal, you
need to implement it as follows :
32
6.3. TURBO PASCAL COMPATIBILITY MODE
Function expr : Longint;
begin
...
Expr:=L:
Writeln (Expr());
...
end;
* Any text after the final End. statement is ignored. Normally, this text is
processed too.
* You cannot assign procedural variables to void pointers.
* The @ operator is typed when applied on procedures.
* You cannot nest comments.
33
Chapter 7
Utilities and units that come
with Free Pascal
Besides the compiler and the Run-Time Library, Free Pascal comes with some utility
programs and units. Here we list these programs and units.
7.1 Supplied programs
ppudump program
ppudump is a program which shows the contents of a Free Pascal unit. It is dis-
tributed with the compiler. You can just issue the following command
ppudump [options] foo.ppu
to display the contents of the foo.ppu unit. You can specify multiple files on the
command line.
The options can be used to change the verbosity of the display. By default, all
available information is displayed. You can set the verbosity level using the -Vxxx
option. Here, xxx is a combination of the following letters:
h: show header info.
i: show interface information.
m: show implementation information.
d: show only (interface) definitions.
s: show only (interface) symbols.
b: show browser info.
a: show everything (default if no -V option is present).
Demo programs
Also distributed with Free Pascal comes a series of demonstration programs. These
programs have no other purpose than demonstrating the capabilities of Free Pascal.
They are located in the demo directory of the sources.
34
7.1. SUPPLIED PROGRAMS
Documentation Example programs
All example programs of the documentation are available. Check out the directories
that end on ex in the documentation sources. There you will find all example
sources.
ppumove program
ppumove is a program to make shared or static libraries from multiple units. It can
be compared with the tpumove program that comes with Turbo Pascal.
It should be distributed in binary form along with the compiler.
It's usage is very simple:
ppumove [options] unit1.ppu unit2.ppu ... unitn.ppu
Where options is a combination of
-b: If specified, ppumve will generate a batch file that will contain the external
linking and archiving commands that must be executed. The name of this
batch file is pmove.sh on linux, and pmove.bat otherwise.
-d xxx: If specified, the output files will put in the directory xxx
-e xxx: Sets the extension of the moved unit files to xxx. By default, this is .ppl.
You don't have to specify the dot.
-o xxx: sets the name of the output file, i.e. the name of the file containing all the
units. This parameter is mandatory when you use multiple files. On linux,
ppumove will prepend this name with lib if it isn't already there, and will add
an extension appropriate to the type of library.
-q: Causes ppumove to operate silently.
-s: Tells ppumove to make a static library instead of a dynamic one; By default a
dynamic library is made on linux.
-w: Tells ppumove that it is working under Windows NT. This will change the
names of te linker and archiving program to ldw and arw, respectively.
-h or -?: will display a short help.
The action of the ppumve program is as follows: It takes each of the unit files, and
modifies it so that the compile will know that it should look for the unit code in the
library. The new unit files will have an extension .ppu, this can be changed with the
-e option. It will then put together all the object files of the units into one library,
static or dynamic, depending on the presence of the -s option.
The name of this library must be set with the -o option. If needed, the prefix lib
will be prepended under linux.. The extension will be set to .a for static libraries,
for shared libraries the extensions are .so on linux, and .dll under Windows NT
and os/2.
As an example, the following command
./ppumove -o both -e ppl ppu.ppu timer.ppu
under linux, will generate the following output:
35
7.1. SUPPLIED PROGRAMS
PPU-Mover Version 0.99.7
Copyright (c) 1998 by the Free Pascal Development Team
Processing ppu.ppu... Done.
Processing timer.ppu... Done.
Linking timer.o ppu.o
Done.
And it will produce the following files:
1. libboth.so : The shared library containing the code from ppu.o and timer.o.
Under Windows NT, this file would be called both.dll.
2. timer.ppl : The unit file that tells the Free Pascal compiler to look for the
timer code in the library.
3. ppu.ppl : The unit file that tells the Free Pascal compiler to look for the timer
code in the library.
You could then use or distribute the files libboth.so, timer.ppl and ppu.ppl.
ptop - Pascal source beautifier
ptop program
ptop is a source beautifier written by Peter Grogono based on the ancient pretty-
printer by Ledgard, Hueras, and Singer, modernized by the Free Pascal team (ob-
jects, streams, configurability etc)
This configurability, and the thorough bottom-up design are the advantages of this
program over the diverse TurboPascal sourcebeautifiers on e.g. SIMTEL.
The program is quite simple to operate:
ptop "[-v] [-i indent] [-b bufsize ][-c optsfile] infile outfile"
The Infile parameter is the pascal file to be processed, and will be written to outfile,
overwriting an existing outfile if it exists.
Some options modify the behaviour of ptop:
-h Writes an overview of the possible parameters and commandline syntax.
-c ptop.cfg Read some configuration data from configuration file instead of using
the internal defaults then. A config file is not required, the program can
operate without one. See also -g.
-i ident Sets the number of indent spaces used for BEGIN END; and other blocks.
-b bufsize Sets the streaming bu ersize to bufsize. Default 255, 0 is considered
non-valid and ignored.
-v be verbose. Currently only outputs the number of lines read/written and some
error messages.
-g ptop.cfg Writes a default configuration file to be edited to the file "ptop.cfg"
36
7.1. SUPPLIED PROGRAMS
Table 7.1: keywords for operators
Name of codeword operator
casevar : in a case label ( unequal 'colon')
becomes :=
delphicomment //
opencomment { or (*
closecomment } or *)
semicolon ;
colon :
equals =
openparen [
closeparen ]
period .
The ptop configuration file
Creating and distributing a configuration file for ptop is not necesarry, unless you
want to modify the standard behaviour of ptop. The configuration file is never
preloaded, so if you want to use it you should always specify it with a -c ptop.cfg
parameter.
The structure of a ptop configuration file is a simple buildingblock repeated several
(20-30) times, for each pascal keyword known to the ptop program. (see the default
configuration file or ptopu.pp source to find out which keywords are known)
The basic building block of the configuration file consists out of one or two lines,
describing how ptop should react on a certain keyword. First a line without square
brackets with the following format:
keyword=option1,option2,option3,...
If one of the options is "dindonkey" (see further below), a second line (with square
brackets) is needed like this:
[keyword]=otherkeyword1,otherkeyword2,otherkeyword3,...
As you can see the block contains two types of identifiers, keywords(keyword and
otherkeyword1..3 in above example) and options, (option1..3 above).
Keywords are the built-in valid Pascal structure-identifiers like BEGIN, END, CASE,
IF, THEN, ELSE, IMPLEMENTATION. The default configuration file lists most
of these.
Besides the real Pascal keywords, some other codewords are used for operators and
comment expressions. table (7.1)
The Options codewords define actions to be taken when the keyword before the
equal sign is found, table (7.2)
The option "dindonkey" requires some extra parameters, which are set by a second
line for that option (the one with the square brackets), which is therefore is only
needed if the options contain "dinkdonkey" (contraction of de-indent on assiociated
keyword).
"dinkdonkey" deindents if any of the keywords specified by the extra options of the
square-bracket line is found.
Example: The lines
37
7.1. SUPPLIED PROGRAMS
Table 7.2: Possible options
Option does what
crsupp suppress CR before the keyword.
crbefore force CR before keyword
(doesn't go with crsupp :) )
blinbefore blank line before keyword.
dindonkey de-indent on associated keywords
(see below)
dindent deindent (always)
spbef space before
spaft space after
gobsym Print symbols which follow a
keyword but which do not
a ect layout. prints until
terminators occur.
(terminators are hard-coded in pptop,
still needs changing)
inbytab indent by tab.
crafter force CR after keyword.
upper prints keyword all uppercase
lower prints keyword all lowercase
capital capitalizes keyword: 1st letter
uppercase, rest lowercase.
else=crbefore,dindonkey,inbytab,upper
[else]=if,then,else
mean the following:
* The keyword this block is about is else because it's on the LEFT side of both
equal signs.
* The option crbefore signals not to allow other code (so just spaces) before
the ELSE keyword on the same line.
* The option dindonkey de-indents if the parser finds any of the keywords in
the square brackets line (if,then,else)
* The option inbytab means indent by a tab.
* The option upper uppercase the keyword (else or Else becomes ELSE)
Try to play with the configfile step by step until you find the e ect you desire. The
configurability and possibilities of ptop are quite large. E.g. I like all keywords
uppercased instead of capitalized, so I replaced all capital keywords in the default
file by upper.
ptop is still development software, so it is wise to visually check the generated source
and try to compile it, to see if ptop hasn't made any errors.
38
7.1. SUPPLIED PROGRAMS
ptopu unit
The source of the PtoP program is conveniently split in two files: One is a unit
containing an object that does the actual beautifying of the source, the other is a
shell built around this object so it can be used from the command line. This design
makes it possible to include the object in some program (e.g. an IDE) and use it's
features to format code.
The object resided in the PtoPU unit, and is declared as follows
TPrettyPrinter=Object(TObject)
Indent : Integer; { How many characters to indent ? }
InS : PStream;
OutS : PStream;
DiagS : PStream;
CfgS : PStream;
Constructor Create;
Function PrettyPrint : Boolean;
end;
Using this object is very simple. The procedure is as follows:
1. Create the object, using it's constructor.
2. Set the Ins stream. This is an open stream, from which pascal source will be
read. This is a mandatory step.
3. Set the OutS stream. This is an open stream, to which the beautified pascal
source will be written. This is a mandatory step.
4. Set the DiagS stream. Any diagnostics will be written to this stream. This
step is optional. If you don't set this, no diagnostics are written.
5. Set the Cfgs stream. A configuration is read from this stream. (see the previ-
ous section for more information about configuration). This step is optional.
If you don't set this, a default configuration is used.
6. Set the Indent variable. This is the number of spaces to use when indenting.
Tab characters are not used in the program. This step is optional. The indent
variable is initialized to 2.
7. Call PrettyPrint. This will pretty-print the source in Ins and write the result
to OutS. The function returns True if no errors occurred, False otherwise.
So, a minimal procedure would be:
Procedure CleanUpCode;
varIns,OutS : PBufStream;
PPRinter : TPrettyPrinter;
begin
Ins:=New(PBufStream,Init('ugly.pp',StopenRead,TheBufSize));
OutS:=New(PBufStream,Init('beauty.pp',StCreate,TheBufSize));
PPrinter.Create;
PPrinter.Ins:=Ins;
39
7.2. SUPPLIED UNITS
PPrinter.outS:=OutS;
PPrinter.PrettyPrint;
end;
Using memory streams allows very fast formatting of code, and is perfectly suitable
for editors.
7.2 Supplied units
Here we list the units that come with the Free Pascal distribution. Since there is
a di erence in the supplied units per operating system, we list them separately per
system. They are documented in the Unit reference.
Under DOS
strings This unit provides basic string handling routines for the pchar type, compa-
rable to similar routines in standard C libraries.
objects This unit provides basic routines for handling objects.
dos This unit provides basic routines for accessing the operating system dos. It
provides almost the same functionality as the Turbo Pascal unit.
printer This unit provides all you need for rudimentary access to the printer.
getopts This unit gives you the gnu getopts command-line arguments handling mech-
anism. It also supports long options.
crt This unit provides basic screen handling routines. It provides the same func-
tionality as the Turbo Pascal CRT unit.
graph This unit provides basic graphics handling, with routines to draw lines on the
screen, display texts etc. It provides the same functions as the Turbo Pascal
unit.
go32 This unit provides access to possibilities of the GO32 dos extender.
emu387 This unit provides support for the coprocessor emulator.
mmx This unit provides support for mmx extensions in your code.
Under Linux
strings This unit provides basic string handling routines for the PChar type, compa-
rable to similar routines in standard C libraries.
objects This unit provides basic routines for handling objects.
crt This unit provides basic screen handling routines. It provides the same func-
tionality Turbo Pascal CRT unit. It works on any terminal which supports the
vt100 escape sequences.
dos This unit provides an emulation of the same unit under dos. It is intended
primarily for easy porting of Pascal programs from dos to linux. For good
performance, however, it is recommended to use the linux unit.
40
7.2. SUPPLIED UNITS
linux This unit provides access to the linux operating system. It provides most
file and I/O handling routines that you may need. It implements most of the
standard C library constructs that you will find on a Unix system. If you do
a lot of disk/file operations, the use of this unit is recommended over the one
you use under Dos.
printer This unit provides an interface to the standard Unix printing mechanism.
getopts This unit gives you the gnu getopts command-line arguments handling mech-
anism. It also supports long options.
mmx This unit provides support for mmx extensions in your code.
sockets This unit gives you access to sockets and TCP/IP programming.
graph Is an implementation of Borlands graph unit, which works on the Linux con-
sole. It's implementation is fairly complete, the only non-functional things
are the fillpatterns and line styles. It uses the libvga and libvgagl graphics
libraries, so you need these installed for this unit to work. Also, programs
using this library need to be run as root, or setuid root, and hence are a
potential security risk.
ports This implements the various port[] constructs. These are provided for com-
patibility only, and it is not recommended to use them extensively. Programs
using this construct must be run as ruit or setuid root, and are a serious
security risk on your system.
41
Chapter 8
Debugging your Programs
Free Pascal supports debug information for the gnu debugger gdb. This chapter
describes shortly how to use this feature. It doesn't attempt to describe completely
the gnu debugger, however. For more information on the workings of the gnu
debugger, see the gdb users' guide.
Free Pascal also suports gprof, the gnu profiler, see section 8.4 for more information
on profiling.
8.1 Compiling your program with debugger sup-
port
First of all, you must be sure that the compiler is compiled with debugging support.
Unfortunately, there is no way to check this at run time, except by trying to compile
a program with debugging support.
To compile a program with debugging support, just specify the -g option on the
command-line, as follows:
ppc386 -g hello.pp
This will generate debugging information in the executable from your program. You
will notice that the size of the executable increases substantially because of this1.
Note that the above will only generate debug information for the code that has
been generated when compiling hello.pp. This means that if you used some units
(the system unit, for instance) which were not compiled with debugging support,
no debugging support will be available for the code in these units.
There are 2 solutions for this problem.
1. Recompile all units manually with the -g option.
2. Specify the 'build' option (-B) when compiling with debugging support. This
will recompile all units, and insert debugging information in each of the units.
The second option may have undesirable side e ects. It may be that some units
aren't found, or compile incorrectly due to missing conditionals, etc..
If all went well, the executable now contains the necessary information with which
you can debug it using gnu gdb.
1A good reason not to include debug information in an executable you plan to distribute.
42
8.2. USING GDB TO DEBUG YOUR PROGRAM
8.2 Using gdb to debug your program
To use gdb to debug your program, you can start the debugger, and give it as an
option the full name of your program:
gdb hello
Or, under dos:
gdb hello.exe
This starts the debugger, and the debugger immediately loads your program into
memory, but it does not run the program yet. Instead, you are presented with the
following (more or less) message, followed by the gdb prompt '(gdb)':
GDB is free software and you are welcome to distribute copies of it
under certain conditions; type "show copying" to see the conditions.
There is absolutely no warranty for GDB; type "show warranty" for details.
GDB 4.15.1 (i486-slackware-linux),
Copyright 1995 Free Software Foundation, Inc...
(gdb)
To start the program you can use the run command. You can optionally specify
command-line parameters, which will then be fed to your program, for example:
(gdb) run -option -anotheroption needed_argument
If your program runs without problems, gdb will inform you of this, and return the
exit code of your program. If the exit code was zero, then the message 'Program
exited normally'.
If something went wrong (a segmentation fault or so), gdb will stop the execution of
your program, and inform you of this with an appropriate message. You can then
use the other gdb commands to see what happened. Alternatively, you can instruct
gdb to stop at a certain point in your program, with the break command.
Here is a short list of gdb commands, which you are likely to need when debugging
your program:
quit Exits the debugger.
kill Stops a running program.
help Gives help on all gdb commands.
file Loads a new program into the debugger.
directory Add a new directory to the search path for source files.
Remark: My copy of gdb needs '.' to be added explicitly to the search path,
otherwise it doesn't find the sources.
list Lists the program sources per 10 lines. As an option you can specify a line
number or function name.
break Sets a breakpoint at a specified line or function
awatch Sets a watch-point for an expression. A watch-point stops execution of
your program whenever the value of an expression is either read or written.
43
8.3. CAVEATS WHEN DEBUGGING WITH GDB
for more information, see the gdb users' guide, or use the 'help' function in gdb.
The appendix F contains a sample init file for gdb, which produces good results
when debugging Free Pascal programs.
It is also possible to use RHIDE, a text-based IDE that uses gdb. There is a version
of RHIDE available that can work together with FPC.
8.3 Caveats when debugging with gdb
There are some peculiarities of Free Pascal which you should be aware of when
using gdb. We list the main ones here:
1. Free Pascal generates information for GDB in uppercare letters. This is a
consequence of the fact that pascal is a case insensitive language. So, when
referring to a variable or function, you need to make it's name all uppercase.
As an example, of you want to watch the value of a loop variable count, you
should type
watch COUNT
Or if you want stop when a certain function (e.g MyFunction) is called, type
break MYFUNCTION
2. Line numbers may be o by a little. This is a bug in Free Pascal and will be
fixed as soon as possible.
3. gdb does not know sets.
4. gdb doesn't know strings. Strings are represented in gdb as records with a
length field and an array of char contaning the string.
You can also use the following user function to print strings:
define pst
set $pos=&$arg0
set $strlen = {byte}$pos
print {char}&$arg0.st@($strlen+1)
end
document pst
Print out a Pascal string
end
If you insert it in your gdb.ini file, you can look at a string with this function.
There is a sample gdb.ini in appendix F.
5. Objects are di cult to handle, mainly because gdb is oriented towards C and
C++. The workaround implemented in Free Pascal is that object methods are
represented as functions, with an extra parameter this (all lowercase !) The
name of this function is a concatenation of the object type and the function
name, separated by two underscore characters.
For example, the method TPoint.Draw would be converted to TPOINT DRAW,
and could be stopped at with
44
8.4. SUPPORT FOR GPROF, THE GNU PROFILER
break TPOINT__DRAW
6. Global overloaded functions confuse gdb because they have the same name.
Thus you cannot set a breakpoint at an overloaded function, unless you know
it's line number, in which case you can set a breakpoint at the starting
linenumber of the function.
8.4 Support for gprof, the gnu profiler
You can compile your programs with profiling support. for this, you just have to use
the compiler switch -pg. The compiler wil insert the necessary stu for profiling.
When you have done this, you can run your program as you normally would run it.
yourexe
Where yourexe is the name of your executable.
When your program finishes a file called gmon.out is generated. Then you can start
the profiler to see the output. You can better redirect the output to a file, becuase
it could be quite a lot:
gprof yourexe > profile.log
Hint: you can use the flat option to reduce the amount of output of gprof. It will
then only output the information about the timings
For more information on the gnu profiler gprof, see its manual.
45
Chapter 9
CGI programming in Free
Pascal
In these days of heavy WWW tra c on the Internet, CGI scripts have become an
important topic in computer programming. While CGI programming can be done
with almost any tool you wish, most languages aren't designed for it. Perl may be
a notable exception, but perl is an interpreted language, the executable is quite big,
and hence puts a big load on the server machine.
Because of its simple, almost intuitive, string handling and its easy syntax, Pascal is
very well suited for CGI programming. Pascal allows you to quickly produce some
results, while giving you all the tools you need for more complex programming.
The basic RTL routines in principle are enough to get the job done, but you can
create, with relatively little e ort, some units which can be used as a base for more
complex CGI programming.
That's why, in this chapter, we will discuss the basics of CGI in Free Pascal. In the
subsequent, we will assume that the server for which the programs are created, are
based upon the NCSA httpd WWW server, as the examples will be based upon
the NCSA method of CGI programming1. They have been tested with the apache
server on linux, and the xitami server on Windows NT.
The two example programs in this chapter have been tested on the command line
and worked, under the condition that no spaces were present in the name and value
pairs provided to them.
There is however, a faster and generally better uncgi unit available, you can find
it on the contributed units page of the Free Pascal web site. It uses techniques
discussed here, but in a generally more e cient way, and it also provides some
extra functionality, not discussed here.
9.1 Getting your data
Your CGI program must react on data the user has filled in on the form which your
web-server gave him. The Web server takes the response on the form, and feeds it
to the CGI script.
There are essentially two ways of feeding the data to the CGI script. We will discuss
both.
1... and it's the only WWW-server I have to my disposition at the moment.
46
9.1. GETTING YOUR DATA
Data coming through standard input.
The first method of getting your data is through standard input. This method is in-
voked when the form uses a form submission method of POST. The web browser sets
three environment variables REQUEST METHOD, CONTENT TYPE and CONTENT LENGTH.
It feeds then the results of the di erent fields through standard input to the CGI
script. All the Pascal program has to do is :
* Check the value of the REQUEST METHOD environment variable. The getenv
function will retrieve this value this for you.
* Check the value of the CONTENT TYPE environment variable.
* Read CONTENT LENGTH characters from standard input. read (c) with c of
type char will take care of that.
if you know that the request method will always be POST, and the CONTENT TYPE
will be correct, then you can skip the first two steps. The third step can be done
easier: read characters until you reach the end-of-file marker of standard input.
The following example shows how this can be achieved:
program cgi_post;
uses dos;
const max_data = 1000;
type datarec = record
name,value : string;
end;
var data : array[1..max_data] of datarec;
i,nrdata : longint;
c : char;
literal,aname : boolean;
begin
writeln ('Content-type: text/html');
writeln;
if getenv('REQUEST_METHOD')<>'POST' then
begin
writeln ('This script should be referenced with a METHOD of POST');
write ('If you don''t understand this, see this ');
write ('< A HREF="http://www.ncsa.uiuc.edu/SDG/Softare/Mosaic');
writeln ('/Docs/fill-out-forms/overview.html">forms overview.');
halt(1);
end;
if getenv('CONTENT_TYPE')<>'application/x-www-form-urlencoded' then
begin
writeln ('This script can only be used to decode form results');
halt(1)
end;
nrdata:=1;
aname:=true;
while not eof(input) do
47
9.1. GETTING YOUR DATA
begin
literal:=false;
read(c);
if c='\' then
begin
literal:=true;
read(c);
end;
if literal or ((c<>'=') and (c<>'&')) then
with data[nrdata] do
if aname then name:=name+c else value:=value+c
elsebegin
if c='&' then
begin
inc (nrdata);
aname:=true;
end
elseaname:=false;
end
end;
writeln ('Form Results :
');
writeln ('You submitted the following name/value pairs :');
writeln ('');
for i:=1 to nrdata do writeln ('- ',data[i].name,' = ',data[i].value);
writeln ('
');
end.
While this program isn't shorter than the C program provided as an example at
NCSA, it doesn't need any other units. everythig is done using standard Pascal
procedures2.
Note that this program has a limitation: the length of names and values is limited
to 255 characters. This is due to the fact that strings in Pascal have a maximal
length of 255. It is of course easy to redefine the datarec record in such a way that
longer values are allowed. In case you have to read the contents of a TEXTAREA form
element, this may be needed.
Data passed through an environment variable
If your form uses the GET method of passing it's data, the CGI script needs to read
the QUERY STRING environment variable to get it's data. Since this variable can,
and probably will, be more than 255 characters long, you will not be able to use
normal string methods, present in pascal. Free Pascal implements the pchar type,
which is a pointer to a null-terminated array of characters. And, fortunately, Free
Pascal has a strings unit, which eases the use of the pchar type.
The following example illustrates what to do in case of a method of GET
program cgi_get;
2actually, this program will give faulty results, since spaces in the input are converted to plus
signs by the web browser. The program doesn't check for this, but that is easy to change. The
main concern here is to give the working principle.
48
9.1. GETTING YOUR DATA
uses strings,linux;
const max_data = 1000;
type datarec = record
name,value : string;
end;
var data : array[1..max_data] of datarec;
i,nrdata : longint;
p : PChar;
literal,aname : boolean;
begin
Writeln ('Content-type: text/html');
Writeln;
if StrComp(GetEnv('REQUEST_METHOD'),'POST')<>0 then
begin
Writeln ('This script should be referenced with a METHOD of GET');
write ('If you don''t understand this, see this ');
write ('< A HREF="http://www.ncsa.uiuc.edu/SDG/Softare/Mosaic');
Writeln ('/Docs/fill-out-forms/overview.html">forms overview.');
halt(1);
end;
p:=GetEnv('QUERY_STRING');
nrdata:=1;
aname:=true;
while p^<>#0 do
begin
literal:=false;
if p^='\' then
begin
literal:=true;
inc(longint(p));
end;
if ((p^<>'=') and (p^<>'&')) or literal then
with data[nrdata] do
if aname then name:=name+p^ else value:=value+p^
elsebegin
if p^='&' then
begin
inc (nrdata);
aname:=true;
end
elseaname:=false;
end;
inc(longint(p));
end;
Writeln ('Form Results :
');
Writeln ('You submitted the following name/value pairs :');
Writeln ('');
for i:=1 to nrdata do writeln ('- ',data[i].name,' = ',data[i].value);
49
9.2. PRODUCING OUTPUT
Writeln ('
');
end.
Although it may not be written in the most elegant way, this program does the
same thing as the previous one. It also su ers from the same drawback, namely the
limited length of the value field of the datarec.
This drawback can be remedied by redefining datarec as follows:
type datarec = record;
name,value : pchar;
end;
and assigning at run time enough space to keep the contents of the value field. This
can be done with a
getmem (data[nrdata].value,needed_number_of_bytes);
call. After that you can do a
strlcopy (data[nrdata].value,p,needed_number_of_bytes);
to copy the data into place.
You may have noticed the following unorthodox call :
inc(longint(p));
Free Pascal doesn't give you pointer arithmetic as in C. However, longints and
pointers have the same length (namely 4 bytes). Doing a type-cast to a longint
allows you to do arithmetic on the pointer.
Note however, that this is a non-portable call. This may work on the I386 processor,
but not on a ALPHA processor (where a pointer is 8 bytes long). This will be
remedied in future releases of Free Pascal.
9.2 Producing output
The previous section concentrated mostly on getting input from the web server. To
send the reply to the server, you don't need to do anything special.You just print
your data on standard output, and the Web-server will intercept this, and send your
output to the WWW-client waiting for it.
You can print anything you want, the only thing you must take care of is that you
supply a Contents-type line, followed by an empty line, as follows:
Writeln ('Content-type: text/html');
Writeln;
{ ...start output of the form... }
And that's all there is to it !
50
9.3. I'M UNDER WINDOWS, WHAT NOW ?
9.3 I'm under Windows, what now ?
Under Windows the system of writing CGI scripts can be totally di erent. If you use
Free Pascal under Windows then you also should be able to do CGI programming,
but the above instructions may not work. They are known to work for the xitami
server, however.
If some kind soul is willing to write a section on CGI programming under Windows
for other servers, I'd be willing to include it here.
51
Appendix A
Alphabetical listing of
command-line options
The following is alphabetical listing of all command-line options, as generated by
the compiler:
ppc386 [options] [options]
put + after a boolean switch option to enable it, - to disable it
-a the compiler doesn't delete the generated assembler file
-al list sourcecode lines in assembler file
-ar list register allocation/release info in assembler file
-at list temp allocation/release info in assembler file
-b generate browser info
-bl generate local symbol info
-B build all modules
-C code generation options:
-CD create dynamic library
-Ch bytes heap (between 1023 and 67107840)
-Ci IO-checking
-Cn omit linking stage
-Co check overflow of integer operations
-Cr range checking
-Cs set stack size to
-Ct stack checking
-CS create static library
-Cx use smartlinking
-d defines the symbol
-e set path to executable
-E same as -Cn
-F set file names and paths:
-FD sets the directory where to search for compiler utilities
-Fe redirect error output to
-FE set exe/unit output path to
-Fi adds to include path
-Fl adds to library path
-Fo adds to object path
-Fr load error message file
-Fu adds to unit path
-FU set unit output path to , overrides -FE
52
-g generate debugger information:
-gg use gsym
-gd use dbx
-gh use heap trace unit
-i information
-iD return compiler date
-iV return compiler version
-iSO return compiler OS
-iSP return compiler processor
-iTO return target OS
-iTP return target processor
-I adds to include path
-k Pass to the linker
-l write logo
-n don't read the default config file
-o change the name of the executable produced to
-pg generate profile code for gprof
-S syntax options:
-S2 switch some Delphi 2 extensions on
-Sc supports operators like C (*=,+=,/= and -=)
-Sd tries to be Delphi compatible
-Se compiler stops after the first error
-Sg allow LABEL and GOTO
-Sh Use ansistrings
-Si support C++ styled INLINE
-Sm support macros like C (global)
-So tries to be TP/BP 7.0 compatible
-Sp tries to be gpc compatible
-Ss constructor name must be init (destructor must be done)
-St allow static keyword in objects
-s don't call assembler and linker (only with -a)
-u undefines the symbol
-U unit options:
-Un don't check the unit name
-Us compile a system unit
-v Be verbose. is a combination of the following letters:
e : Show errors (default) d : Show debug info
w : Show warnings u : Show unit info
n : Show notes t : Show tried/used files
h : Show hints m : Show defined macros
i : Show general info p : Show compiled procedures
l : Show linenumbers c : Show conditionals
a : Show everything 0 : Show nothing (except errors)
b : Show all procedure r : Rhide/GCC compatibility mode
declarations if an error x : Executable info (Win32 only)
occurs
-X executable options:
-XD link with dynamic libraries (defines FPC_LINK_DYNAMIC)
-Xs strip all symbols from executable
-XS link with static libraries (defines FPC_LINK_STATIC)
Processor specific options:
-A output format:
-Ao coff file using GNU AS
53
-Anasmcoff coff file using Nasm
-Anasmelf elf32 (Linux) file using Nasm
-Anasmobj obj file using Nasm
-Amasm obj file using Masm (Microsoft)
-Atasm obj file using Tasm (Borland)
-R assembler reading style:
-Ratt read AT&T style assembler
-Rintel read Intel style assembler
-Rdirect copy assembler text directly to assembler file
-O optimizations:
-Og generate smaller code
-OG generate faster code (default)
-Or keep certain variables in registers (still BUGGY!!!)
-Ou enable uncertain optimizations (see docs)
-O1 level 1 optimizations (quick optimizations)
-O2 level 2 optimizations (-O1 + slower optimizations)
-O3 level 3 optimizations (same as -O2u)
-Op target processor:
-Op1 set target processor to 386/486
-Op2 set target processor to Pentium/PentiumMMX (tm)
-Op3 set target processor to PPro/PII/c6x86/K6 (tm)
-T Target operating system:
-TGO32V1 version 1 of DJ Delorie DOS extender
-TGO32V2 version 2 of DJ Delorie DOS extender
-TLINUX Linux
-TOS2 OS/2 2.x
-TWin32 Windows 32 Bit
-? shows this help
-h shows this help without waiting
54
Appendix B
Alphabetical list of reserved
words
absolute file packed
abstract finally popstack
and for private
array forward procedure
as function program
asm goto property
assembler if protected
begin implementation public
break in raise
case index record
cdecl inherited repeat
class initialization self
const inline set
constructor interface shl
continue interrupt shr
destructor is stdcall
dispose label string
div library then
do mod to
downto name true
else near try
end new type
except nil unit
exit not until
export object uses
exports of var
external on virtual
fail operator while
false or with
far otherwise xor
55
Appendix C
Compiler messages
This appendix is meant to list all the compiler messages. The list of messages is
generated from he compiler source itself, and should be faitly complete. At this
point, only assembler errors are not in the list.
C.1 General compiler messages
This section gives the compiler messages which are not fatal, but which display
useful information. The number of such messages can be controlled with the various
verbosity level -v switches.
Compiler: arg1 When the -vt switch is used, this line tells you what compiler is
used.
Compiler OS: arg1 When the -vd switch is used, this line tells you what the
source operating system is.
Info: Target OS: arg1 When the -vd switch is used, this line tells you what the
target operating system is.
Using executable path: arg1 When the -vt switch is used, this line tells you
where the compiler looks for it's binaries.
Using unit path: arg1 When the -vt switch is used, this line tells you where the
compiler looks for compiled units. You can set this path with the -Fu
Using include path: arg1 When the -vt switch is used, this line tells you where
the compiler looks for it's include files (files used in {$I xxx} statements).
You can set this path with the -I option.
Using library path: arg1 When the -vt switch is used, this line tells you where
the compiler looks for the libraries. You can set this path with the -Fl option.
Using object path: arg1 When the -vt switch is used, this line tells you where
the compiler looks for object files you link in (files used in {$L xxx} state-
ments). You can set this path with the -Fo option.
Info: arg1 Lines compiled, arg2 sec When the -vi switch is used, the compiler
reports the number of lines compiled, and the time it took to compile them
(real time, not program time).
56
C.2. SCANNER MESSAGES.
Fatal: No memory left The compiler doesn't have enough memory to compile
your program. There are several remedies for this:
* If you're using the build option of the compiler, try compiling the di erent
units manually.
* If you're compiling a huge program, split it up in units, and compile
these separately.
* If the previous two don't work, recompile the compiler with a bigger heap
(you can use the -Ch option for this, See 5.1)
C.2 Scanner messages.
This section lists the messages that the scanner emits. The scanner takes care of
the lexical structure of the pascal file, i.e. it tries to find reserved words, strings,
etc. It also takes care of directives and conditional compiling handling.
Fatal: Unexpected end of file this typically happens in one of the following
cases :
* The source file ends before the final end. statement. This happens
mostly when the begin and end statements aren't balanced;
* An include file ends in the middle of a statement.
* A comment wasn't closed.
Fatal: String exceeds line You forgot probably to include the closing ' in a
string, so it occupies multiple lines.
Fatal: illegal character An illegal character was encountered in the input file.
Fatal: Syntax error, arg1 expected but arg2 found This indicates that the
compiler expected a di erent token than the one you typed. It can occur
almost everywhere where you make a mistake against the pascal language.
Start reading includefile arg1 When you provide the -vt switch, the compiler
tells you when it starts reading an included file.
Warning: Comment level arg1 found When the -vw switch is used, then the
compiler warns you if it finds nested comments. Nested comments are not
allowed in Turbo Pascal and can be a possible source of errors.
Note: argF directive (FAR) ignored The FAR directive is a 16-bit construction
which is recorgnised but ignored by the compiler, since it produces 32 bit code.
Note: Stack check is global under Linux Stack checking with the -Cs switch
is ignored under linux, since linux does this for you. Only displayed when
-vn is used.
Note: Ignored compiler switch arg1 With -vn on, the compiler warns if it ig-
nores a switch
Warning: Illegal compiler switch arg1 You included a compiler switch (i.e.
{$... }) which the compiler doesn't know.
Warning: This compiler switch has a global e ect When -vw is used, the
compiler warns if a switch is global.
57
C.2. SCANNER MESSAGES.
Error: Illegal char constant This happens when you specify a character with
its ASCII code, as in #96, but the number is either illegal, or out of range.
The range is 1-255.
Fatal: Can't open file arg1 Free Pascal cannot find the program or unit source
file you specified on the command line.
Fatal: Can't open include file arg1 Free Pascal cannot find the source file you
specified in a {$include ..} statement.
Error: Too many argENDIFs or argELSEs Your {$IFDEF ..} and {$ENDIF}
statements aren't balanced.
Warning: Records fields can be aligned to 1,2,4 or 16 bytes only You are
specifying the {$PACKRECORDS n} with an illegal value for n. Only 1,2,4 or
16 are valid in this case.
Warning: Enumerated can be saved in 1,2 or 4 bytes only You are speci-
fying the {$PACKENUM n} with an illegal value for n. Only 1,2 or 4 are valid
in this case.
Error: arg1 expected for arg2 defined in line arg3 Your conditional compi-
lation statements are unbalanced.
Error: Syntax error while parsing a conditional compiling expression There
is an error in the expression following the {$if ..} compiler directive.
Error: Evaluating a conditional compiling expression There is an error in
the expression following the {$if ..} compiler directive.
Warning: Macro contents is cut after char 255 to evalute expression The
contents of macros canno be longer than 255 characters. This is a safety in
the compiler, to prevent bu er overflows. This is shown as a warning, i.e.
when the -vw switch is used.
Error: ENDIF without IF(N)DEF Your {$IFDEF ..} and {$ENDIF} state-
ments aren't balanced.
Fatal: User defined: arg1 A user defined fatal error occurred. see also the Pro-
grammers' guide
Error: User defined: arg1 A user defined error occurred. see also the Program-
mers' guide
Warning: User defined: arg1 A user defined warning occurred. see also the
Programmers' guide
Note: User defined: arg1 A user defined note was encountered. see also the
Programmers' guide
Hint: User defined: arg1 A user defined hint was encountered. see also the
Programmers' guide
Info: User defined: arg1 User defined information was encountered. see also
the Programmers' guide
Error: Keyword redefined as macro has no e ect You cannot redefine key-
words with macros.
58
C.2. SCANNER MESSAGES.
Fatal: Macro bu er overflow while reading or expanding a macro Your macro
or it's result was too long for the compiler.
Warning: Extension of macros exceeds a deep of 16. When expanding a macro
macros have been nested to a level of 16. The compiler will expand no further,
since this may be a sign that recursion is used.
Error: compiler switches aren't allowed in (* ... *) styled comments Compiler
switches should always be between { } comment delimiters.
Handling switch "arg1" When you set debugging info on (-vd) the compiler
tells you when it is evaluating conditional compile statements.
ENDIF arg1 found When you turn on conditional messages(-vc), the compiler
tells you where it encounters conditional statements.
IFDEF arg1 found, arg2 When you turn on conditional messages(-vc), the com-
piler tells you where it encounters conditional statements.
IFOPT arg1 found, arg2 When you turn on conditional messages(-vc), the com-
piler tells you where it encounters conditional statements.
IF arg1 found, arg2 When you turn on conditional messages(-vc), the compiler
tells you where it encounters conditional statements.
IFNDEF arg1 found, arg2 When you turn on conditional messages(-vc), the
compiler tells you where it encounters conditional statements.
ELSE arg1 found, arg2 When you turn on conditional messages(-vc), the com-
piler tells you where it encounters conditional statements.
Skipping until... When you turn on conditional messages(-vc), the compiler tells
you where it encounters conditional statements, and whether it is skipping or
compiling parts.
Info: Press ¡return¿ to continue When the -vi switch is used, the compiler
stops compilation and waits for the Enter key to be pressed when it encounters
a {$STOP} directive.
Warning: Unsupported switch arg1 When warings are turned on (-vw) the
compiler warns you about unsupported switches. This means that the switch
is used in Delphi or Turbo Pascal, but not in Free Pascal
Warning: Illegal compiler directive arg1 When warings are turned on (-vw)
the compiler warns you about unrecognised switches. For a list of recognised
switches, Programmers' guide
Back in arg1 When you use (-vt) the compiler tells you when it has finished
reading an include file.
Warning: Unsupported application type: arg1 You get this warning, you
specify an unknown application type with the directive {$APPTYPE}
Warning: APPTYPE isn't support by the target OS The {$APPTYPE} di-
rective is supported by win32 applications only.
Warning: Unsupported assembler style specified arg1 When you specify an
assembler mode with the {$ASMMODE xxx} the compiler didn't recognize the
mode you specified.
59
C.3. PARSER MESSAGES
Warning: ASM reader switch is not possible inside asm statement, arg1 will be e ective only for next
It is not possible to switch from one assembler reader to another inside an ass-
mebler block. The new reader will be used for next assembler statement only.
Error: Wrong switch toggle, use ON/OFF or +/- You need to use ON or
OFF or a + or - to toggle the switch
Error: Resource files are not supported for this target The target you are
compiling for doesn't support Resource files. The only target which can use
resource files is Win32
C.3 Parser messages
This section lists all parser messages. The parser takes care of the semantics of you
language, i.e. it determines if your pascal constructs are correct.
Error: Parser - Syntax Error An error against the Turbo Pascal language was
encountered. This happens typically when an illegal character is found in the
sources file.
Warning: Procedure type FAR ignored This is a warning. FAR is a construct
for 8 or 16 bit programs. Since the compile generates 32 bit programs, it
ignores this directive.
Warning: Procedure type NEAR ignored This is a warning. NEAR is a con-
struct for 8 or 16 bit programs. Since the compile generates 32 bit programs,
it ignores this directive.
Warning: Procedure type REGISTER ignored This is a warning. REGISTER
is ignored by FPC programs for now. This is introduced first for Delphi
compatibility.
Error: No DLL File specified No longer in use.
Error: Duplicate exported function name arg1 Exported function names in-
side a specific DLL must all be di erent
Error: Duplicate exported function index arg1 Exported function names in-
side a specific DLL must all be di erent
Error: Invalid index for exported function DLL function index must be in
the range 1..$FFFF
Error: Constructor name must be INIT You are declaring a constructor with
a name which isn't init, and the -Ss switch is in e ect. See the -Ss switch
(See 5.1).
Error: Destructor name must be DONE You are declaring a constructor with
a name which isn't done, and the -Ss switch is in e ect. See the -Ss switch
(See 5.1).
Error: Illegal open parameter You are trying to use the wrong type for an open
parameter.
Error: Procedure type INLINE not supported You tried to compile a pro-
gram with C++ style inlining, and forgot to specify the -Si option (See 5.1).
The compiler doesn't support C++ styled inlining by default.
60
C.3. PARSER MESSAGES
Warning: Private methods shouldn't be VIRTUAL You declared a method
in the private part of a object (class) as virtual. This is not allowed. Private
methods cannot be overridden anyway.
Warning: Constructor should be public Constructors must be in the 'public'
part of an object (class) declaration.
Warning: Destructor should be public Destructors must be in the 'public' part
of an object (class) declaration.
Note: Class should have one destructor only You can declare only one de-
structor for a class.
Error: Local class definitions are not allowed Classes must be defined glob-
ally. They cannot be defined inside a procedure or function
Fatal: Anonym class definitions are not allowed An invalid object (class) dec-
laration was encountered, i.e. an object or class without methods that isn't
derived from another object or class. For example:
Type o = object
a : longint;
end;
will trigger this error.
Error: The object arg1 has no VMT
Error: Illegal parameter list You are calling a function with parameters that
are of a di erent type than the declared parameters of the function.
Error: Wrong parameter type specified for arg no. arg1 There is an error
in the parameter list of the function or procedure. The compiler cannot de-
termine the error more accurate than this.
Error: Wrong amount of parameters specified There is an error in the pa-
rameter list of the function or procedure, the number of parameters is not
correct.
Error: overloaded identifier arg1 isn't a function The compiler encountered
a symbol with the same name as an overloaded function, but it isn't a function
it can overload.
Error: overloaded functions have the same parameter list You're declaring
overloaded functions, but with the same parameter list. Overloaded function
must have at least 1 di erent parameter in their declaration.
Error: function header doesn't match the forward declaration arg1 You de-
clared a function with same parameters but di erent result type or function
specifiers.
Error: function header arg1 doesn't match forward : var name changes arg2 =¿ arg3
You declared the function in the interface part, or with the forward direc-
tive, but define it with a di erent parameter list.
Note: Values in enumeration types have to be ascending Free Pascal allows
enumeration constructions as in C. Given the following declaration two dec-
larations:
61
C.3. PARSER MESSAGES
type a = (A_A,A_B,A_E:=6,A_UAS:=200);
type a = (A_A,A_B,A_E:=6,A_UAS:=4);
The second declaration would produce an error. A UAS needs to have a value
higher than A E, i.e. at least 7.
Note: Interface and implementation names are di erent arg1 =¿ arg2 This
note warns you if the implementation and interface names of a functions are
di erent, but they have the same mangled name. This is important when
using overloaded functions (but should produce no error).
Error: With can not be used for variables in a di erent segment With stores
a variable locally on the stack, but this is not possible if the variable belongs
to another segment.
Error: function nesting ¿ 31 You can nest function definitions only 31 times.
Error: range check error while evaluating constants The constants are out
of their allowed range.
Warning: range check error while evaluating constants The constants are
out of their allowed range.
Error: duplicate case label You are specifying the same label 2 times in a case
statement.
Error: Upper bound of case range is less than lower bound The upper bound
of a case label is less than the lower bound and this is useless
Error: typed constants of classes are not allowed You cannot declare a con-
stant of type class or object.
Error: functions variables of overloaded functions are not allowed You are
trying to assign an overloaded function to a procedural variable. This isn't
allowed.
Error: string length must be a value from 1 to 255 The length of a string
in Pascal is limited to 255 characters. You are trying to declare a string with
length lower than 1 or greater than 255 (This is not true for Longstrings and
AnsiStrings.
Warning: use extended syntax of NEW and DISPOSE for instances of objects
If you have a pointer a to a class type, then the statement new(a) will not
initialize the class (i.e. the constructor isn't called), although space will be
allocated. you should issue the new(a,init) statement. This will allocate
space, and call the constructor of the class.
Warning: use of NEW or DISPOSE for untyped pointers is meaningless
Error: use of NEW or DISPOSE is not possible for untyped pointers You
cannot use new(p) or dispose(p) if p is an untyped pointer because no size
is associated to an untyped pointer. Accepted for compatibility in tp and
delphi modes.
Error: class identifier expected This happens when the compiler scans a pro-
cedure declaration that contains a dot, i.e., a object or class method, but the
type in front of the dot is not a known type.
62
C.3. PARSER MESSAGES
Error: type identifier not allowed here You cannot use a type inside an ex-
pression.
Error: method identifier expected This identifier is not a method. This hap-
pens when the compiler scans a procedure declaration that contains a dot,
i.e., a object or class method, but the procedure name is not a procedure of
this type.
Error: function header doesn't match any method of this class This iden-
tifier is not a method. This happens when the compiler scans a procedure dec-
laration that contains a dot, i.e., a object or class method, but the procedure
name is not a procedure of this type.
procedure/function arg1 When using the -vp switch, the compiler tells you
when it starts processing a procedure or function implementation.
Error: Illegal floating point constant The compiler expects a floating point
expression, and gets something else.
Error: FAIL can be used in constructors only You are using the FAIL in-
struction outside a constructor method.
Error: Destructors can't have parameters You are declaring a destructor with
a parameter list. Destructor methods cannot have parameters.
Error: Only class methods can be referred with class references This er-
ror occurs in a situation like the following:
Type :
Tclass = Class of Tobject;
Var C : TClass;
begin
...
C.free
Free is not a class method and hence cannot be called with a class reference.
Error: Only class methods can be accessed in class methods This is related
to the previous error. You cannot call a method of an object from a inside a
class method. The following code would produce this error:
class procedure tobject.x;
begin
free
Because free is a normal method of a class it cannot be called from a class
method.
Error: Constant and CASE types do not match One of the labels is not of
the same type as the case variable.
63
C.3. PARSER MESSAGES
Error: The symbol can't be exported from a library You can only export
procedures and functions when you write a library. You cannot export vari-
ables or constants.
Warning: An inherited method is hidden by arg1 A method that is declared
virtual in a parent class, should be overridden in the descendent class with
the override directive. If you don't specify the override directive, you will
hide the parent method; you will not override it.
Error: There is no method in an ancestor class to be overridden: arg1 You
try to override a virtual method of a parent class that doesn't exist.
Error: No member is provided to access property You specified no read di-
rective for a property.
Warning: Stored prorperty directive is not yet implemented The stored
directive is not yet implemented
Error: Illegal symbol for property access There is an error in the read or
write directives for an array property. When you declare an array property,
you can only access it with procedures and functions. The following code
woud cause such an error.
tmyobject = class
i : integer;
property x [i : integer]: integer read I write i;
Error: Cannot access a protected field of an object here Fields that are de-
clared in a protected section of an object or class declaration cannot be ac-
cessed outside the module wher the object is defined, or outside descendent
object methods.
Error: Cannot access a private field of an object here Fields that are de-
clared in a private section of an object or class declaration cannot be accessed
outside the module where the class is defined.
Warning: overloaded method of virtual method should be virtual: arg1
If you declare overloaded methods in a class, then they should either all be
virtual, or none. You shouldn't mix them.
Warning: overloaded method of non-virtual method should be non-virtual: arg1
If you declare overloaded methods in a class, then they should either all be
virtual, or none. You shouldn't mix them.
Error: overloaded methods which are virtual must have the same return type: arg1
If you declare virtual overloaded methods in a class definition, they must have
the same return type.
Error: EXPORT declared functions can't be nested You cannot declare a
function or procedure within a function or procedure that was declared as an
export procedure.
Error: methods can't be EXPORTed You cannot declare a procedure that is
a method for an object as exported. That is, your methods cannot be called
from a C program.
64
C.3. PARSER MESSAGES
Error: call by var parameters have to match exactly When calling a func-
tion declared with var parameters, the variables in the function call must be
of exactly the same type. There is no automatic type conversion.
Error: Class isn't a parent class of the current class When calling inherited
methods, you are trying to call a method of a strange class. You can only call
an inherited method of a parent class.
Error: SELF is only allowed in methods You are trying to use the self pa-
rameter outside an object's method. Only methods get passed the self pa-
rameters.
Error: methods can be only in other methods called direct with type identifier of the class
A construction like sometype.somemethod is only allowed in a method.
Error: Illegal use of ':' You are using the format : (colon) 2 times on an ex-
pression that is not a real expression.
Error: range check error in set constructor or duplicate set element The
declaration of a set contains an error. Either one of the elements is outside
the range of the set type, either two of the elements are in fact the same.
Error: Pointer to object expected You specified an illegal type in a New state-
ment. The extended synax of New needs an object as a parameter.
Error: Expression must be constructor call When using the extended syntax
of new, you must specify the constructor method of the object you are trying
to create. The procedure you specified is not a constructor.
Error: Expression must be destructor call When using the extended syntax
of dispose, you must specify the destructor method of the object you are
trying to dispose of. The procedure you specified is not a destructor.
Error: Illegal order of record elements When declaring a constant record, you
specified the fields in the wrong order.
Error: Expression type must be class or record type A with statement needs
an argument that is of the type record or class. You are using with on an
expression that is not of this type.
Error: Procedures can't return a value In Free Pascal, you can specify a re-
turn value for a function when using the exit statement. This error occurs
when you try to do this with a procedure. Procedures cannot return a value.
Error: constructors and destructors must be methods You're declaring a pro-
cedure as destructor or constructor, when the procedure isn't a class method.
Error: Operator is not overloaded You're trying to use an overloaded operator
when it isn't overloaded for this type.
Error: Re-raise isn't possible there You are trying to raise an exception where
it isn't allowed. You can only raise exceptions in an except block.
Error: The extended syntax of new or dispose isn't allowed for a class You
cannot generate an instance of a class with the extended syntax of new. The
constructor must be used for that. For the same reason, you cannot call
Dispose to de-allocate an instance of a class, the destructor must be used for
that.
65
C.3. PARSER MESSAGES
Error: Assembler incompatible with function return type You're trying to
implement a assembler function, but the return type of the function doesn't
allow that.
Error: Procedure overloading is switched o When using the -So switch, pro-
cedure overloading is switched o . Turbo Pascal does not support function
overloading.
Error: It is not possible to overload this operator (overload = instead)
You are trying to overload an operator which cannot be overloaded. The fol-
lowing operators can be overloaded :
+, -, *, /, =, >, <, <=, >=, is, as, in, **, :=
Error: Comparative operator must return a boolean value When overload-
ing the = operator, the function must return a boolean value.
Error: Only virtual methods can be abstract You are declaring a method as
abstract, when it isn't declared to be virtual.
Fatal: Use of unsupported feature! You're trying to force the compiler into
doing something it cannot do yet.
Error: The mix of CLASSES and OBJECTS isn't allowed You cannot de-
rive objects and classes intertwined . That is, a class cannot have an object
as parent and vice versa.
Warning: Unknown procedure directive had to be ignored: arg1 The pro-
cedure direcive you secified is unknown. Recognised procedure directives are
cdecl, stdcall, popstack, pascal register, export.
Error: absolute can only be associated to ONE variable You cannot spec-
ify more than one variable before the absolute directive. Thus, the following
construct will provide this error:
Var Z : Longint;
X,Y : Longint absolute Z;
absolute can only be associated a var or const The address of a absolute
directive can only point to a variable or constant. Therefore, the following
code will produce this error:
Procedure X;
var p : longint absolute x;
Error: absolute can only be associated a var or const The address of a absolute
directive can only point to a variable or constant. Therefore, the following
code will produce this error:
Procedure X;
var p : longint absolute x;
66
C.3. PARSER MESSAGES
Error: Only ONE variable can be initialized You cannot specify more than
one variable with a initial value in Delphi syntax.
Error: Abstract methods shouldn't have any definition (with function body)
Abstract methods can only be declared, you cannot implement them. They
should be overridden by a descendant class.
Error: This overloaded function can't be local (must be exported) You are
defining a overloaded function in the implementation part of a unit, but there
is no corresponding declaration in the interface part of the unit.
Warning: Virtual methods are used without a constructor in arg1 If you
declare objects or classes that contain virtual methods, you need to have a con-
structor and destructor to initialize them. The compiler encountered an object
or class with virtual methods that doesn't have a constructor/destructor pair.
Macro defined: arg1 When -vm is used, the compiler tells you when it defines
macros.
Macro undefined: arg1 When -vm is used, the compiler tells you when it unde-
fines macros.
Macro arg1 set to arg2 When -vm is used, the compiler tells you what values
macros get.
Info: Compiling arg1 When you turn on information messages (-vi), the com-
piler tells you what units it is recompiling.
Compiling arg1 for the second time When you request debug messages (-vd)
the compiler tells you what units it recompiles for the second time.
Error: Array properties aren't allowed at this point You cannot use array
properties at that point.a
Error: No property found to override You want to overrride a property of a
parent class, when there is, in fact, no such property in the parent class.
Error: Only one default property is allowed, found inherited default property in class arg1
You specified a property as Default, but a parent class already has a default
property, and a class can have only one default property.
Error: The default property must be an array property Only array prop-
erties of classes can be made default properties.
Error: Virtual constructors are only supported in class object model You
cannot have virtual constructors in objects. You can only have them in classes.
Error: No default property available You try to access a default property of
a class, but this class (or one of it's ancestors) doesn't have a default property.
Error: The class can't have a published section, use the argM+ switch If
you want a published section in a class definition, you must use the {$M+}
switch, whch turns on generation of type information.
Error: Forward declaration of class arg1 must be resolved here to use the class as ancestor
To be able to use an object as an ancestor object, it must be defined first.
This error occurs in the following situation:
67
C.3. PARSER MESSAGES
Type ParentClas = Class;
ChildClass = Class(ParentClass)
...
end;
Where ParentClass is declared but not defined.
Error: Local operators not supported You cannot overload locally, i.e. inside
procedures or function definitions.
Error: Procedure directive arg1 not allowed in interface section This pro-
cedure directive is not allowed in the interface section of a unit. You can
only use it in the implementation section.
Error: Procedure directive arg1 not allowed in implementation section This
procedure directive is not defined in the implementation section of a unit.
You can only use it in the interface section.
Error: Procedure directive arg1 not allowed in procvar declaration This pro-
cedure directive cannot be part of a procedural of function type declaration.
Error: Function is already declared Public/Forward arg1 You will get this
error if a function is defined as forward twice. Or it is once in the interface
section, and once as a forward declaration in the implmentation section.
Error: Can't use both EXPORT and EXTERNAL These two procedure di-
rectives are mutually exclusive
Error: NAME keyword expected The definition of an external variable needs
a name clause.
Warning: arg1 not yet supported inside inline procedure/function Inline
procedures don't support this declaration.
Warning: Inlining disabled Inlining of procedures is disabled.
Info: Writing Browser log arg1 When information messages are on, the com-
piler warns you when it writes the browser log (generated with the {$Y+ }
switch).
Hint: may be pointer dereference is missing The compiler thinks that a pointer
may need a dereference.
Fatal: Selected assembler reader not supported The selected assembler reader
(with {$ASMMODE xxx} is not supported. The compiler can be compiled with
or without support for a particular assembler reader.
Error: Procedure directive arg1 has conflicts with other directives You spec-
ified a procedure directive that conflicts with other directives. for instance
cdecl and pascal are mutually exclusive.
Error: Calling convention doesn't match forward This error happens when
you declare a function or procedure with e.g. cdecl; but omit this directive
in the implementation, or vice versa. The calling convention is part of the
function declaration, and must be repeated in the function definition.
Error: Register calling (fastcall) not supported The register calling con-
vention, i.e., arguments are passed in registers instead of on the stack is not
supported. Arguments are always passed on the stack.
68
C.3. PARSER MESSAGES
Error: Property can't have a default value Set properties or indexed proper-
ties cannot have a default value.
Error: The default value of a property must be constant The value of a default
declared property must be knwon at compile time. The value you specified is
only known at run time. This happens .e.g. if you specify a variable name as
a default value.
Error: Symbol can't be published, can be only a class Only class type vari-
ables can be in a published section of a class if they are not declared as a
property.
Error: That kind of property can't be published Properties in a published
section cannot be array properties. they must be moved to public sections.
Properties in a published section must be an ordinal type, a real type, strings
or sets.
Warning: Empty import name specified Both index and name for the import
are 0 or empty
Warning: Empty import name specified Some targets need a name for the
imported procedure or a cdecl specifier
Error: Function internal name changed after use of function
Error: Division by zero There is a divsion by zero encounted
Error: Invalid floating point operation An operation on two real type values
produced an overflow or a division by zero.
Error: Upper bound of range is less than lower bound The upper bound of
a case label is less than the lower bound and this is not possible
Error: string length is larger than array of char length The size of the con-
stant string is larger than the size you specified in the array[x..y] of char
definition
Error: Illegal expression after message directive Free Pascal supports only
integer or string values as message constants
Error: Message handlers can take only one call by ref. parameter A method
declared with the message-directive as message handler can take only one pa-
rameter which must be declared as call by reference Parameters are declared
as call by reference using the var-directive
Error: Duplicate message label: arg1 A label for a message is used twice in
one object/class
Error: Self can be only an explicit parameter in message handlers The self
parameter can be passed only explicit if it is a method which is declared as
message method handler
Error: Threadvars can be only static or global Threadvars must be static or
global, you can't declare a thread local to a procedure. Local variables are
always local to a thread, because every thread has it's own stack and local
variables are stored on the stack
Fatal: Direct assembler not supported for binary output format You can't
use direct assembler when using a binary writer, choose an other outputformat
or use an other assembler reader
69
C.4. TYPE CHECKING ERRORS
Warning: Don't load OBJPAS unit manual, use argmode objfpc or argmode delphi instead
You're trying to load the ObjPas unit manual from a uses clause. This is not a
good idea to do, you can better use the {$mode objfpc} or {$mode delphi}
directives which load the unit automaticly
Error: OVERRIDE can't be used in objects Override isn't support for ob-
jects, use VIRTUAL instead to override a method of an anchestor object
Error: Data types which requires initialization/finalization can't be used in variant records
Some data type (e.g. ansistring) needs initialization/finalization code which
is implicitly generated by the compiler. Such data types can't be used in the
variant part of a record.
C.4 Type checking errors
This section lists all errors that can occur when type checking is performed.
Error: Type mismatch This can happen in many cases:
* The variable you're assigning to is of a di erent type than the expression
in the assignment.
* You are calling a function or procedure with parameters that are incom-
patible with the parameters in the function or procedure definition.
Error: Incompatible types: got "arg1" expected "arg2" There is no con-
version possible between the two types Another possiblity is that they are
declared in di erent declarations:
VarA1 : Array[1..10] Of Integer;
A2 : Array[1..10] Of Integer;
Begin
A1:=A2; { This statement gives also this error, it
is due the strict type checking of pascal }
End.
Error: Type mismatch between arg1 and arg2 The types are not equal
Error: Integer expression expected The compiler expects an expression of type
integer, but gets a di erent type.
Error: Ordinal expression expected The expression must be of ordinal type,
i.e., maximum a Longint. This happens, for instance, when you specify a
second argument to Inc or Dec that doesn't evaluate to an ordinal value.
Error: Type identifier expected The identifier is not a type, or you forgot to
supply a type identifier.
Error: Variable identifier expected This happens when you pass a constant to
a Inc var or Dec procedure. You can only pass variables as arguments to these
functions.
Error: pointer type expected The variable or expression isn't of the type pointer.
This happens when you pass a variable that isn't a pointer to New or Dispose.
70
C.4. TYPE CHECKING ERRORS
Error: class type expected The variable of expression isn't of the type class.
This happens typically when
1. The parent class in a class declaration isn't a class.
2. An exception handler (On) contains a type identifier that isn't a class.
Error: Variable or type indentifier expected The argument to the High or
Low function is not a variable nor a type identifier.
Error: Can't evaluate constant expression No longer in use.
Error: Set elements are not compatible You are trying to make an operation
on two sets, when the set element types are not the same. The base type of
a set must be the same when taking the union
Error: Operation not implemented for sets several binary operations are not
defined for sets like div mod ** (also ¿= ¡= for now)
Warning: Automatic type conversion from floating type to COMP which is an integer type
An implicit type conversion from a real type to a comp is encountered. Since
Comp is a 64 bit integer type, this may indicate an error.
Hint: use DIV instead to get an integer result When hints are on, then an
integer division with the '/' operator will procuce this message, because the
result will then be of type real
Error: string types doesn't match, because of argV+ mode When compil-
ing in {$V+} mode, the string you pass as a parameter should be of the exact
same type as the declared parameter of the procedure.
Error: succ or pred on enums with assignments not possible When you de-
clared an enumeration type which has assignments in it, as in C, like in the
following:
Tenum = (a,b,e:=5);
you cannot use the Succ or Pred functions on them.
Error: Can't read or write variables of this type You are trying to read or
write a variable from or to a file of type text, which doesn't support that.
Only integer types, booleans, reals, pchars and strings can be read from/written
to a text file.
Error: Type conflict between set elements There is at least one set element
which is of the wrong type, i.e. not of the set type.
Warning: lo/hi(dword/qword) returns the upper/lower word/dword Free
Pascal supports an overloaded version of lo/hi for longint/dword/int64/qword
which returns the lower/upper word/dword of the argument. TP always uses
a 16 bit lo/hi which returns always bits 0..7 for lo and the bits 8..15 for
hi. If you want the TP behavior you have to type cast the argument to
word/integer
Error: Integer or real expression expected The first argument to str must a
real or integer type.
Error: Wrong type in array constructor You are trying to use a type in an
array constructor which is not allowed.
71
C.5. SYMBOL HANDLING
Error: Incompatible type for arg no. arg1: Got arg2, expected arg3 You
are trying to pass an invalid type for the specified parameter.
Error: Method (variable) and Procedure (variable) are not compatible You
can't assign a method to a procedure variable or a procedure to a method
pointer.
Error: Illegal constant passed to internal math function The constant ar-
gument passed to a ln or sqrt function is out of the definition range of these
functions.
Error: Can't get the address of constants It's not possible to get the address
of a constant, because they aren't stored in memory, you can try making it a
typed constant.
C.5 Symbol handling
This section lists all the messages that concern the handling of symbols. This means
all things that have to do with procedure and variable names.
Error: Identifier not found arg1 The compiler doesn't know this symbol. Usu-
ally happens when you misspel the name of a variable or procedure, or when
you forgot to declare a variable.
Fatal: Internal Error in SymTableStack() An internal error occurred in the
compiler; If you encounter such an error, please contact the developers and
try to provide an exact description of the circumstances in which the error
occurs.
Error: Duplicate identifier arg1 The identifier was already declared in the cur-
rent scope.
Hint: Identifier already defined in arg1 at line arg2 The identifier was al-
ready declared in a previous scope.
Error: Unknown identifier arg1 The identifier encountered hasn't been declared,
or is used outside the scope where it's defined.
Error: Forward declaration not solved arg1 This can happen in two cases:
* This happens when you declare a function (in the interface part, or
with a forward directive, but do not implement it.
* You reference a type which isn't declared in the current type block.
Fatal: Identifier type already defined as type You are trying to redefine a
type.
Error: Error in type definition There is an error in your definition of a new
array type:
One of the range delimiters in an array declaration is erroneous. For example,
Array [1..1.25] will trigger this error.
Error: Type identifier not defined The type identifier has not been defined
yet.
Error: Forward type not resolved arg1 The compiler encountered an unknown
type.
72
C.5. SYMBOL HANDLING
Error: Only static variables can be used in static methods or outside methods
A static method of an object can only access static variables.
Error: Invalid call to tvarsym.mangledname() An internal error occurred in
the compiler; If you encounter such an error, please contact the developers
and try to provide an exact description of the circumstances in which the
error occurs.
Fatal: record or class type expected The variable or expression isn't of the
type record or class.
Error: Instances of classes or objects with an abstract method are not allowed
You are trying to generate an instance of a class which has an abstract method
that wasn't overridden.
Warning: Label not defined arg1 A label was declared, but not defined.
Error: Illegal label declaration
Error: GOTO and LABEL are not supported (use switch -Sg) You must
compile a program which has labels and goto statements with the -Sg switch.
By default, label and goto aren't supported.
Error: Label not found A goto label was encountered, but the label isn't de-
clared.
Error: identifier isn't a label The identifier specified after the goto isn't of type
label.
Error: label already defined You are defining a label twice. You can define a
label only once.
Error: illegal type declaration of set elements The declaration of a set con-
tains an invalid type definition.
Error: Forward class definition not resolved arg1 You declared a class, but
you didn't implement it.
Hint: Parameter not used arg1 This is a warning. The identifier was declared
(locally or globally) but wasn't used (locally or globally).
Note: Local variable not used arg1 You have declared, but not used a variable
in a procedure or function implementation.
Error: Set type expected The variable or expression isn't of type set. This
happens in an in statement.
Warning: Function result does not seem to be set You can get this warning
if the compiler thinks that a function return value is not set. This will not
be displayed for assembler procedures, or procedures that contain assembler
blocks.
Error: Unknown record field identifier arg1 The field doesn't exist in the record
definition.
Warning: Local variable arg1 does not seem to be initialized
Warning: Variable arg1 does not seem to be initialized These messages are
displayed if the compiler thinks that a variable will be used (i.e. appears in the
right-hand-side of an expression) when it wasn't initialized first (i.e. appeared
in the left-hand side of an assigment)
73
C.6. CODE GENERATOR MESSAGES
Error: identifier idents no member arg1 When using the extended syntax of
new, you must specify the constructor method of the class you are trying to
create. The procedure you specified does not exist.
Found declaration: arg1 You get this when you use the -vb switch. In case an
overloaded procedure is not found, then all candidate overloaded procedures
are listed, with their parameter lists.
C.6 Code generator messages
This section lists all messages that can be displayed if the code generator encounters
an error condition.
Error: BREAK not allowed You're trying to use break outside a loop construc-
tion.
Error: CONTINUE not allowed You're trying to use continue outside a loop
construction.
Error: Expression too complicated - FPU stack overflow Your expression is
too long for the compiler. You should try dividing the construct over multiple
assignments.
Error: Illegal expression This can occur under many circumstances. Mostly
when trying to evaluate constant expressions.
Error: Invalid integer expression You made an expression which isn't an inte-
ger, and the compiler expects the result to be an integer.
Error: Illegal qualifier One of the following is happening :
* You're trying to access a field of a variable that is not a record.
* You're indexing a variable that is not an array.
* You're dereferencing a variable that is not a pointer.
Error: High range limit ¡ low range limit You are declaring a subrange, and
the lower limit is higher than the high limit of the range.
Error: Illegal counter variable The type of a for loop variable must be an
ordinal type. Loop variables cannot be reals or strings.
Error: Can't determine which overloaded function to call You're calling over-
loaded functions with a parameter that doesn't correspond to any of the de-
clared function parameter lists. e.g. when you have declared a function with
parameters word and longint, and then you call it with a parameter which
is of type integer.
Error: Parameter list size exceeds 65535 bytes The I386 processor limits the
parameter list to 65535 bytes (the RET instruction causes this)
Error: Illegal type conversion When doing a type-cast, you must take care that
the sizes of the variable and the destination type are the same.
Conversion between ordinals and pointers is not portable across platforms
If you typecast a pointer to a longint, this code will not compile on a machine
using 64bit for pointer storage.
74
C.6. CODE GENERATOR MESSAGES
Error: File types must be var parameters You cannot specify files as value
parameters, i.e. they must always be declared var parameters.
Error: The use of a far pointer isn't allowed there Free Pascal doesn't sup-
port far pointers, so you cannot take the address of an expression which has
a far reference as a result. The mem construct has a far reference as a result,
so the following code will produce this error:
var p : pointer;
...
p:=@mem[a000:000];
Error: illegal call by reference parameters You are trying to pass a constant
or an expression to a procedure that requires a var parameter. Only variables
can be passed as a var parameter.
Error: EXPORT declared functions can't be called No longer in use.
Warning: Possible illegal call of constructor or destructor (doesn't match to this context)
No longer in use.
Note: Ine cient code You construction seems dubious to the compiler.
Warning: unreachable code You specified a loop which will never be executed.
Example:
while false do
begin
{.. code ...}
end;
Error: procedure call with stackframe ESP/SP The compiler encountered a
procedure or function call inside a procedure that uses a ESP/SP stackframe.
Normally, when a call is done the procedure needs a EBP stackframe.
Error: Abstract methods can't be called directly You cannot call an abstract
method directy, instead you must call a overriding child method, because an
abstract method isn't implemented.
Fatal: Internal Error in getfloatreg(), allocation failure An internal error oc-
curred in the compiler; If you encounter such an error, please contact the de-
velopers and try to provide an exact description of the circumstances in which
the error occurs.
Fatal: Unknown float type The compiler cannot determine the kind of float
that occurs in an expression.
Fatal: SecondVecn() base defined twice An internal error occurred in the com-
piler; If you encounter such an error, please contact the developers and try to
provide an exact description of the circumstances in which the error occurs.
Fatal: Extended cg68k not supported The varextended type is not supported
on the m68k platform.
Fatal: 32-bit unsigned not supported in MC68000 mode The cardinal is not
supported on the m68k platform.
75
C.7. UNIT LOADING MESSAGES.
Fatal: Internal Error in secondinline() An internal error occurred in the com-
piler; If you encounter such an error, please contact the developers and try to
provide an exact description of the circumstances in which the error occurs.
Register arg1 weight arg2 arg3 Debugging message. Shown when the compiler
considers a variable for keeping in the registers.
Error: Stack limit excedeed in local routine Your code requires a too big stack.
Some operating systems pose limits on the stack size. You should use less vari-
ables or try ro put large variables on the heap.
Stack frame is omitted Some procedure/functions do not need a complete stack-
frame, so it is omitted. This message will be displayed when the -vd switch
is used.
Error: Object or class methods can't be inline. You cannot have inlined ob-
ject methods.
Error: Procvar calls can't be inline. A procedure with a procedural variable
call cannot be inlined.
Error: No code for inline procedure stored The compiler couldn't store code
for the inline procedure.
Error: Element zero of an ansi/wide- or longstring can't be accessed, use (set)length instead
You should use setlength to set the length of an ansi/wide/longstring and
length to get the length of such kinf of string
Error: Include and exclude not implemented in this case include and exclude
are only partially implemented for i386 processors and not at all for m68k pro-
cessors.
Error: Constructors or destructors can not be called inside a 'with' clause
Inside a With clause you cannot call a constructor or destructor for the object
you have in the with clause.
Error: Cannot call message handler method directly A message method han-
dler method can't be called directly if it contains an explicit self argument
C.7 Unit loading messages.
This section lists all messages that can occur when the compiler is loading a unit
from disk into memory. Many of these mesages are informational messages.
Unitsearch: arg1 When you use the -vt, the compiler tells you where it tries to
find unit files.
PPU Loading arg1 When the -vt switch is used, the compiler tells you what
units it loads.
PPU Name: arg1 When you use the -vu flag, the unit name is shown.
PPU Flags: arg1 When you use the -vu flag, the unit flags are shown.
PPU Crc: arg1 When you use the -vu flag, the unit CRC check is shown.
PPU Time: arg1 When you use the -vu flag, the unit time is shown.
76
C.7. UNIT LOADING MESSAGES.
PPU File too short When you use the -vu flag, the unit time is shown.
PPU Invalid Header (no PPU at the begin) A unit file contains as the first
three bytes the ascii codes of PPU
PPU Invalid Version arg1 This unit file was compiled with a di erent version
of the compiler, and cannot be read.
PPU is compiled for an other processor This unit file was compiled for a dif-
ferent processor type, and cannot be read
PPU is compiled for an other target This unit file was compiled for a di er-
ent processor type, and cannot be read
PPU Source: arg1 When you use the -vu flag, the unit CRC check is shown.
Writing arg1 When you specify the -vu switch, the compiler will tell you where
it writes the unit file.
Fatal: Can't Write PPU-File An err
Fatal: reading PPU-File Unexpected end of file
Fatal: unexpected end of PPU-File This means that the unit file was cor-
rupted, and contains invalid information. Recompilation will be necessary.
Fatal: Invalid PPU-File entry: arg1 The unit the compiler is trying to read is
corrupted, or generated with a newer version of the compiler.
Fatal: PPU Dbx count problem There is an inconsistency in the debugging
information of the unit.
Error: Illegal unit name: arg1 The name of the unit doesn't match the file
name.
Fatal: Too much units Free Pascal has a limit of 1024 units in a program. You
can change this behavior by changing the maxunits constant in the files.pas
file of the compiler, and recompiling the compiler.
Fatal: Circular unit reference between arg1 and arg2 Two units are using
each other in the interface part. This is only allowed in the implementation
part. At least one unit must contain the other one in the implementation
section.
Fatal: Can't compile unit arg1, no sources available A unit was found that
needs to be recompiled, but no sources are available.
Warning: Compiling the system unit requires the -Us switch When recom-
piling the system unit (it needs special treatment), the -Us must be specified.
Fatal: There were arg1 errors compiling module, stopping When the com-
piler encounters a fatal error or too many errors in a module then it stops with
this message.
Load from arg1 (arg2) unit arg3 When you use the -vu flag, which unit is
loaded from which unit is shown.
Recompiling arg1, checksum changed for arg2
Recompiling arg1, source found only When you use the -vu flag, these mes-
sages tell you why the current unit is recompiled.
77
C.8. COMMAND-LINE HANDLING ERRORS
Recompiling unit, static lib is older than ppufile When you use the -vu flag,
the compiler warns if the static library of the unit are older than the unit file
itself.
Recompiling unit, shared lib is older than ppufile When you use the -vu flag,
the compiler warns if the shared library of the unit are older than the unit file
itself.
Recompiling unit, obj and asm are older than ppufile When you use the -vu
flag, the compiler warns if the assembler of object file of the unit are older
than the unit file itself.
Recompiling unit, obj is older than asm When you use the -vu flag, the com-
piler warns if the assembler file of the unit is older than the object file of the
unit.
Parsing interface of arg1 When you use the -vu flag, the compiler warns that
it starts parsing the interface part of the unit
Parsing implementation of arg1 When you use the -vu flag, the compiler warns
that it starts parsing the implementation part of the unit
Second load for unit arg1 When you use the -vu flag, the compiler warns that
it starts recompiling a unit for the second time. This can happend with
interdepend units.
PPU Check file arg1 time arg2 When you use the -vu flag, the compiler show
the filename and date and time of the file which a recompile depends on
C.8 Command-line handling errors
This section lists errors that occur when the compiler is processing the command
line or handling the configuration files.
Warning: Only one source file supported You can specify only one source file
on the command line. The first one will be compiled, others will be ignored.
This may indicate that you forgot a '-' sign.
Warning: DEF file can be created only for OS/2 This option can only be
specified when you're compiling for OS/2
Error: nested response files are not supported you cannot nest response files
with the @file command-line option.
Fatal: No source file name in command line The compiler expects a source
file name on the command line.
Error: Illegal parameter: arg1 You specified an unknown option.
Hint: -? writes help pages When an unknown option is given, this message is
diplayed.
Fatal: Too many config files nested You can only nest up to 16 config files.
Fatal: Unable to open file arg1 The option file cannot be found.
Note: Reading further options from arg1 Displayed when you have notes turned
on, and the compiler switches to another options file.
78
C.9. ASSEMBLER READER ERRORS.
Warning: Target is already set to: arg1 Displayed if more than one -T option
is specified.
Warning: Shared libs not supported on DOS platform, reverting to static
If you specify -CD for the dos platform, this message is displayed. The com-
piler supports only static libraries under dos
Fatal: too many IF(N)DEFs the #IF(N)DEF statements in the options file are
not balanced with the #ENDIF statements.
Fatal: too many ENDIFs the #IF(N)DEF statements in the options file are not
balanced with the #ENDIF statements.
Fatal: open conditional at the end of the file the #IF(N)DEF statements in
the options file are not balanced with the #ENDIF statements.
Warning: Debug information generation is not supported by this executable
It is possible to have a compiler executable that doesn't support the genera-
tion of debugging info. If you use such an executable with the -g switch, this
warning will be displayed.
Hint: Try recompiling with -dGDB It is possible to have a compiler executable
that doesn't support the generation of debugging info. If you use such an ex-
ecutable with the -g switch, this warning will be displayed.
Error: You are using the obsolete switch arg1 this warns you when you use
a switch that is not needed/supported anymore. It is recommended that
you remove the switch to overcome problems in the future, when the switch
meaning may change.
Error: You are using the obsolete switch arg1, please use arg2 this warns
you when you use a switch that is not supported anymore. You must now use
the second switch instead. It is recommended that you change the switch to
overcome problems in the future, when the switch meaning may change.
Note: Switching assembler to default source writing assembler this noti-
fies you that the assembler has been changed because you used the -a switch
which can't be used with a binary assembler writer.
C.9 Assembler reader errors.
This section lists the errors that are generated by the inline assembler reader. They
are not the messages of the assembler itself.
General assembler errors
Divide by zero in asm evaluator This fatal error is reported when a constant
assembler expressions does a division by zero.
Evaluator stack overflow, Evaluator stack underflow These fatal errors are
reported when a constant assembler expression is too big to evaluate by the
constant parser. Try reducing the number of terms.
Invalid numeric format in asm evaluator This fatal error is reported when a
non-numeric value is detected by the constant parser. Normally this error
should never occur.
79
C.9. ASSEMBLER READER ERRORS.
Invalid Operator in asm evaluator This fatal error is reported when a math-
ematical operator is detected by the constant parser. Normally this error
should never occur.
Unknown error in asm evaluator This fatal error is reported when an internal
error is detected by the constant parser. Normally this error should never
occur.
Invalid numeric value This warning is emitted when a conversion from octal,binary
or hexadecimal to decimal is outside of the supported range.
Escape sequence ignored This error is emitted when a non ANSI C escape se-
quence is detected in a C string.
Asm syntax error - Prefix not found This occurs when trying to use a non-
valid prefix instruction
Asm syntax error - Trying to add more than one prefix This occurs when
you try to add more than one prefix instruction
Asm syntax error - Opcode not found You have tried to use an unsupported
or unknown opcode
Constant value out of bounds This error is reported when the constant parser
determines that the value you are using is out of bounds, either with the
opcode or with the constant declaration used.
Non-label pattern contains @ This only applied to the m68k and Intel styled
assembler, this is reported when you try to use a non-label identifier with a
'@' prefix.
Internal error in Findtype()
Internal Error in ConcatOpcode()
Internal Errror converting binary
Internal Errror converting hexadecimal
Internal Errror converting octal
Internal Error in BuildScaling()
Internal Error in BuildConstant()
internal error in BuildReference()
internal error in HandleExtend()
Internal error in ConcatLabeledInstr() These errors should never occur, if
they do then you have found a new bug in the assembler parsers. Please
contact one of the developers.
Opcode not in table, operands not checked This warning only occurs when
compiling the system unit, or related files. No checking is performed on the
operands of the opcodes.
@CODE and @DATA not supported This Turbo Pascal construct is not sup-
ported.
SEG and OFFSET not supported This Turbo Pascal construct is not supported.
80
C.9. ASSEMBLER READER ERRORS.
Modulo not supported Modulo constant operation is not supported.
Floating point binary representation ignored
Floating point hexadecimal representation ignored
Floating point octal representation ignored These warnings occur when a float-
ing point constant are declared in a base other then decimal. No conversion
can be done on these formats. You should use a decimal representation in-
stead.
Identifier supposed external This warning occurs when a symbol is not found
in the symolb table, it is therefore considered external.
Functions with void return value can't return any value in asm code Only
routines with a return value can have a return value set.
Error in binary constant
Error in octal constant
Error in hexadecimal constant
Error in integer constant These errors are reported when you tried using an
invalid constant expression, or that the value is out of range.
Invalid labeled opcode
Asm syntax error - error in reference
Invalid Opcode
Invalid combination of opcode and operands
Invalid size in reference
Invalid middle sized operand
Invalid three operand opcode
Assembler syntax error
Invalid operand type You tried using an invalid combination of opcode and
operands, check the syntax and if you are sure it is correct, please contact
one of the developers.
Unknown identifier The identifier you are trying to access does not exist, or is
not within the current scope.
Trying to define an index register more than once
Trying to define a segment register twice
Trying to define a base register twice You are trying to define an index/segment
register more then once.
Invalid field specifier The record or object field you are trying to access does not
exist, or is incorrect.
Invalid scaling factor
Invalid scaling value
81
C.9. ASSEMBLER READER ERRORS.
Scaling value only allowed with index Allowed scaling values are 1,2,4 or 8.
Cannot use SELF outside a method You are trying to access the SELF iden-
tifier for objects outside a method.
Invalid combination of prefix and opcode This opcode cannot be prefixed by
this instruction
Invalid combination of override and opcode This opcode cannot be overri-
den by this combination
Too many operands on line At most three operand instructions exist on the
m68k, and i386, you are probably trying to use an invalid syntax for this
opcode.
Duplicate local symbol You are trying to redefine a local symbol, such as a local
label.
Unknown label identifer
Undefined local symbol
local symbol not found inside asm statement This label does not seem to
have been defined in the current scope
Assemble node syntax error
Not a directive or local symbol The assembler statement is invalid, or you are
not using a recognized directive.
I386 specific errors
repeat prefix and a segment override on <= i386 ... A problem with interrupts
and a prefix instruction may occur and may cause false results on 386 and
earlier computers.
Fwait can cause emulation problems with emu387 This warning is reported
when using the FWAIT instruction, it can cause emulation problems on sys-
tems which use the em387.dxe emulator.
You need GNU as version ¿= 2.81 to compile this MMX code MMX as-
sembler code can only be compiled using GAS v2.8.1 or later.
NEAR ignored
FAR ignored NEAR and FAR are ignored in the intel assemblers, but are still ac-
cepted for compatiblity with the 16-bit code model.
Invalid size for MOVSX/MOVZX
16-bit base in 32-bit segment
16-bit index in 32-bit segment 16-bit addressing is not supported, you must
use 32-bit addressing.
Constant reference not allowed It is not allowed to try to address a constant
memory address in protected mode.
Segment overrides not supported Intel style (eg: rep ds stosb) segment over-
rides are not support by the assembler parser.
82
C.9. ASSEMBLER READER ERRORS.
Expressions of the form [sreg:reg... are currently not supported] To access a
memory operand in a di erent segment, you should use the sreg:[reg...] snytax
instead of [sreg:reg...]
Size su x and destination register do not match In intel AT&T syntax, you
are using a register size which does not concord with the operand size specified.
Invalid assembler syntax. No ref with brackets
Trying to use a negative index register
Local symbols not allowed as references
Invalid operand in bracket expression
Invalid symbol name:
Invalid Reference syntax
Invalid string as opcode operand:
Null label references are not allowed
Using a defined name as a local label
Invalid constant symbol
Invalid constant expression
/ at beginning of line not allowed
NOR not supported
Invalid floating point register name
Invalid floating point constant:
Asm syntax error - Should start with bracket
Asm syntax error - register:
Asm syntax error - in opcode operand
Invalid String expression
Constant expression out of bounds
Invalid or missing opcode
Invalid real constant expression
Parenthesis are not allowed
Invalid Reference
Cannot use SELF outside a method
Cannot use OLDEBP outside a nested procedure
Invalid segment override expression
Strings not allowed as constants
Switching sections is not allowed in an assembler block
83
C.9. ASSEMBLER READER ERRORS.
Invalid global definition
Line separator expected
Invalid local common definition
Invalid global common definition
assembler code not returned to text
invalid opcode size
Invalid character: ¡
Invalid character: ¿
Unsupported opcode
Invalid su x for intel assembler
Extended not supported in this mode
Comp not supported in this mode
Invalid Operand:
Override operator not supported
m68k specific errors.
Increment and Decrement mode not allowed together You are trying to use
dec/inc mode together.
Invalid Register list in movem/fmovem The register list is invalid, normally
a range of registers should be separated by - and individual registers should
be separated by a slash.
Invalid Register list for opcode
68020+ mode required to assemble
84
Appendix D
Run time errors
The Free Pascal Run-time library generates the following errors at run-time 1:
1 Invalid function number You tried to call a dos function which doesn't exist.
2 File not found You can get this error when you tried to do an operation on a
file which doesn't exist.
3 Path not found You can get this error when you tried to do an operation on a
file which doesn't exist, or when you try to change to, or remove a directory
that doesn't exist, or try to make a subdirectory of a subdirectory that doesn't
exist.
4 Too many open files When attempting to open a file for reading or writing,
you can get this error when your program has too many open files.
5 File access denied You don't have access to the specified file.
6 Invalid file handle If this happens, the file variable you are using is trashed; it
indicates that your memory is corrupted.
12 Invalid file access code This will happen if you do a reset or rewrite of a file
when FileMode is invalid.
15 Invalid drive number The number given to the Getdir function specifies a
non-existent disk.
16 Cannot remove current directory You get this if you try to remove the
current diirectory.
17 Cannot rename across drives You cannot rename a file such that it would
end up on another disk or partition.
100 Disk read error dos only. An error occurred when reading from disk. Typ-
ically when you try to read past the end of a file.
101 Disk write error dos only. Reported when the disk is full, and you're trying
to write to it.
102 File not assigned This is reported by Reset, Rewrite, Append, Rename and
Erase, if you call them with an unassigne function as a parameter.
1The linux port will generate only a subset of these.
85
103 File not open Reported by the following functions : Close , Read, Write,
Seek, EOf, FilePos, FileSize, Flush, BlockRead, and BlockWrite if the file
isn't open.
104 File not open for input Reported by Read, BlockRead, Eof, Eoln, SeekEof
or SeekEoln if the file isn't opened with Reset.
105 File not open for output Reported by write if a text file isn't opened with
Rewrite.
106 Invalid numeric format Reported when a non-numerice value is read from
a text file, when a numeric value was expected.
150 Disk is write-protected (Critical error, dos only.)
151 Bad drive request struct length (Critical error, dos only.)
152 Drive not ready (Critical error, dos only.)
154 CRC error in data (Critical error, dos only.)
156 Disk seek error (Critical error, dos only.)
157 Unknown media type (Critical error, dos only.)
158 Sector Not Found (Critical error, dos only.)
159 Printer out of paper (Critical error, dos only.)
160 Device write fault (Critical error, dos only.)
161 Device read fault (Critical error, dos only.)
162 Hardware failure (Critical error, dos only.)
200 Division by zero You are dividing a number by zero.
201 Range check error If you compiled your program with range checking on,
then you can get this error in the following cases:
1. An array was accessed with an index outside its declared range.
2. You're trying to assign a value to a variable outside its range (for instance
a enumerated type).
202 Stack overflow error The stack has grown beyond itss maximum size. This
error can easily occur if you have recursive functions.
203 Heap overflow error The heap has grown beyond its boundaries, ad you are
rying to get more memory. Please note that Free Pascal provides a growing
heap, i.e. the heap will try to allocate more memory if needed. However, if
the heap has reached the maximum size allowed by the operating system or
hardware, then you will get this error.
204 Invalid pointer operation This you will get if you call dispose or Freemem
with an invalid pointer (notably, Nil)
205 Floating point overflow You are trying to use or produce too large real
numbers.
206 Floating point underflow You are trying to use or produce too small real
numbers.
86
207 Invalid floating point operation Can occur if you try to calculate the square
root or logarithm of a negative number.
210 Object not initialized When compiled with range checking on, a program
will report this error if you call a virtal method without having initialized the
VMT.
211 Call to abstract method Your program tried to execute an abstract virtual
method. Abstract methods should be overridden, and the overriding method
should be called.
212 Stream registration error This occurs when an invalid type is registered in
the objects unit.
213 Collection index out of range You are trying to access a collection item
with an invalid index. (objects unit)
214 Collection overflow error The collection has reached its maximal size, and
you are trying to add another element. (objects unit)
216 General Protection fault You are trying to access memory outside your
appointed memory.
217 Unhandled exception occurred An exception occurred, and there was no
exception handler present. The sysutils unit installs a default exception han-
dler which catches all excpetions and exits gracefully.
227 Assertion failed error An assertion failed, and no AssertErrorProc proce-
dural variable was installed.
87
Appendix E
The Floating Point
Coprocessor emulator
In this appendix we note some caveats when using the floating point emulator on
GO32V2 systems. Under GO32V1 systems, all is as described in the installation
section.
Q: I don't have an 80387. How do I compile and run floating point programs under
GO32V2?
Q: What shall I install on a target machine which lacks hardware floating-point
support?
A : Programs which use floating point computations and could be run on machines
without an 80387 should be allowed to dynamically load the emu387.dxe file at
run-time if needed. To do this you must link the emu387 unit to your exectuable
program, for example:
Program MyFloat;
Uses emu387;
var
r: real;
Begin
r:=1.0;
WriteLn(r);
end.
Emu387 takes care of loading the dynamic emulation point library.
You should always add emulation when you distribute floating-point programs.
A few users reported that the emulation won't work for them unless they explicitly
tell DJGPP there is no x87 hardware, like this:
set 387=N
set emu387=c:/djgpp/bin/emu387.dxe
There is an alternative FP emulator called WMEMU. It mimics a real coprocessor
more closely.
88
WARNING: We strongly suggest that you use WMEMU as FPU emulator, since
emu387.dxe does not emulate all the instructions which are used by the Run-Time
Libary such as FWAIT.
Q: I have an 80387 emulator installed in my AUTOEXEC.BAT, but DJGPP-
compiled floating point programs still doesn't work. Why?
A : DJGPP switches the CPU to protected mode, and the information needed to
emulate the 80387 is di erent. Not to mention that the exceptions never get to the
real-mode handler. You must use emulators which are designed for DJGPP. Apart
of emu387 and WMEMU, the only other emulator known to work with DJGPP is
Q87 from QuickWare. Q87 is shareware and is available from the QuickWare Web
site.
Q: I run DJGPP in an os/2 DOS box, and I'm told that os/2 will install its
own emulator library if the CPU has no FPU, and will transparently execute FPU
instructions. So why won't DJGPP run floating-point code under os/2 on my
machine?
A : os/2 installs an emulator for native os/2 images, but does not provide FPU
emulation for DOS sessions.
89
Appendix F
A sample gdb.ini file
Here you have a sample gdb.ini file listing, which gives better results when using
gdb. Under linux you should put this in a .gdbinit file in your home directory or
the current directory..
set print demangle off
set gnutarget auto
set verbose on
set complaints 1000
dir ./rtl/dosv2
set language c++
set print vtbl on
set print object on
set print sym on
set print pretty on
disp /i $eip
define pst
set $pos=&$arg0
set $strlen = {byte}$pos
print {char}&$arg0.st@($strlen+1)
end
document pst
Print out a pascal string
end
90