Linux Compilers and Assemblers

3.10 Compiling Pascal Programs

Pascal programs can be converted to C language programs and then compiled in the usual way. The p2c command on Linux does this for you. Consider the following Pascal program hello.pas.

(* Program to demonstrate Pascal compilation *)
program Hello ;
begin
   writeln ('Hello world')
end.

The following command will create a file hello.c which is the equivalent C version of the hello.pas program.

[rr@conformix 4]$ p2c hello.pas
   Hello
   
   Translation completed.
   [rr@conformix 4]$
   

The output hello.c file is shown below:

/* Output from p2c 1.21alpha-07.Dec.93, the Pascal-to-C translator */
/* From input file "hello.pas" */


/* Program to demonstrate Pascal compilation */

#include <p2c/p2c.h>


main(argc, argv)
int argc;
Char *argv[];
{
  PASCAL_MAIN(argc, argv);
  printf("Hello world\n");
  exit(EXIT_SUCCESS);
}




/* End. */

You may need some libraries with p2c program and C compiler to successfully complete this process.

Many Pascal compilers are also available in the open source world. These compilers can be used to generate executable code from Pascal source directly without any help from GCC.

3.10.1 Using Free Pascal (fpc)

The Free Pascal Project has created a 32-bit Pascal compiler which is available for Linux, among other operating systems. You can download it from http://www.freepascal.org. This software is licensed under GPL like other open source projects. At the time of writing this book version 1.0.4 is available for download. After download, you can install the compiler as follows on a RedHat system:

[root@conformix rr]# rpm --install fpc-1.0.4.i386.rpm
   Write permission in /etc.
   Found libgcc.a in /usr/lib/gcc-lib/i386-redhat-linux/2.96
   Writing sample configuration file to /etc/ppc386.cfg
   [root@conformix rr]#
   

The best thing about this compiler is that you don't need to convert source code files to C language and then compile these. The fpc compiler creates binary executable files. The following command creates an executable file hello from hello.pas program listed earlier.

[rr@conformix 4]$ fpc hello.pas
   Free Pascal Compiler version 1.0.4 [2000/12/18] for i386
   Copyright (c) 1993-2000 by Florian Klaempfl
   Target OS: Linux for i386
   Compiling hello.pas
   Assembling hello
   Linking hello
   6 Lines compiled, 0.1 sec
   [rr@conformix 4]$
   

The output hello program can be executed like any other program.

3.10.2 Using GNU Pascal

A GNU Pascal compiler is available from http://agnes.dida.physik.uni-essen.de/~gnu-pascal/ for download and can be installed on many platforms like gcc. The web site contains all manuals and downloadable files for this compiler. This compiler also creates executable files from Pascal source code.