Free Pascal Compiler (FPC) is a

compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...

for the closely related programming-language dialects Pascal and

Object Pascal Object Pascal is an extension to the programming language Pascal (programming language), Pascal that provides object-oriented programming (OOP) features such as Class (computer programming), classes and Method (computer programming), methods. T ...

. It is

free software Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...

released under the

GNU General Public License The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

, wit
exception clauses
that allow static linking against its runtime libraries and packages for any purpose in combination with any other software license. It supports its own Object Pascal dialect, as well as the dialects of several other Pascal family compilers to a certain extent, including those of Borland Pascal (named "Turbo Pascal" until the 1990 version 6), Borland (later Embarcadero)

Delphi Delphi (; ), in legend previously called Pytho (Πυθώ), was an ancient sacred precinct and the seat of Pythia, the major oracle who was consulted about important decisions throughout the ancient Classical antiquity, classical world. The A ...

, and some historical

Macintosh Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...

compilers. The dialect is selected on a per-unit (module) basis, and more than one dialect can be used per program. It follows a '' write once, compile anywhere'' philosophy and is available for many CPU architectures and

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

s (see Targets). It supports inline

assembly language In computing, assembly language (alternatively assembler language or symbolic machine code), often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence bet ...

and includes an internal assembler capable of parsing several dialects such as AT&T and Intel style. There are separate projects to facilitate developing

cross-platform Within computing, cross-platform software (also called multi-platform software, platform-agnostic software, or platform-independent software) is computer software that is designed to work in several Computing platform, computing platforms. Some ...

graphical user interface A graphical user interface, or GUI, is a form of user interface that allows user (computing), users to human–computer interaction, interact with electronic devices through Graphics, graphical icon (computing), icons and visual indicators such ...

(GUI) applications, the most prominent one being the Lazarus

integrated development environment An integrated development environment (IDE) is a Application software, software application that provides comprehensive facilities for software development. An IDE normally consists of at least a source-code editor, build automation tools, an ...

(IDE).

Supported dialects

Initially, Free Pascal adopted the ''de facto'' standard dialect of Pascal programmers, Borland Pascal, but later adopted Delphi's Object Pascal. From version 2.0 on, Delphi compatibility has been continuously implemented or improved. The project has a ''compilation mode'' concept, and the developers made it clear that they would incorporate working patches for the standardized dialects of the

American National Standards Institute The American National Standards Institute (ANSI ) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organiz ...

(ANSI) and

International Organization for Standardization The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. M ...

(ISO) to create a standards-compliant mode. A small effort has been made to support some of the

Apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

Pascal syntax to ease interfacing to the

Classic Mac OS Mac OS (originally System Software; retronym: Classic Mac OS) is the series of operating systems developed for the Mac (computer), Macintosh family of personal computers by Apple Computer, Inc. from 1984 to 2001, starting with System 1 and end ...

and

macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

. The Apple dialect implements some standard Pascal features that Turbo Pascal and Delphi omit. The 2.2.''x'' release series did not significantly change the dialect objectives beyond roughly Delphi 7 level syntax, instead aiming for closer compatibility. A notable exception to this was the addition of support fo
generics
to Free Pascal in version 2.2.0, several years before they were supported in any capacity by Delphi. In 2011 several Delphi 2006-specific features were added in the development branch, and some of the starting work for the features new in Delphi 2009 (most notably the addition of the UnicodeString type) was completed. The development branch also has an ''Objective-Pascal'' extension for

Objective-C Objective-C is a high-level general-purpose, object-oriented programming language that adds Smalltalk-style message passing (messaging) to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was ...

( Cocoa) interfacing. As of version 2.7.1, Free Pascal implemented basic ISO Pascal mode, though many things such as the Get and Put procedures, and the file-buffer variable concept for file handling were still absent. As of version 3.0.0, ISO Pascal mode is fairly complete. It has been able to compil
standardpascal.org
s P5 ISO Pascal compiler with no changes.

History

Early years

Free Pascal was created when Borland clarified that Borland Pascal development for DOS would stop with version 7, to be replaced by a

Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

-only product, which later became Delphi. Student Florian Paul Klämpfl began developing his own compiler written in the Turbo Pascal dialect and produced

32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in a maximum of 32- bit units. Compared to smaller bit widths, 32-bit computers can perform la ...

code for the GO32v1 DOS extender, which was used and developed by the DJ's GNU Programming Platform ( DJGPP) project at that time. Originally, the compiler was a

16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two ...

DOS executable compiled by Turbo Pascal. After two years, the compiler was able to compile itself and became a 32-bit executable.

Expansion

The initial 32-bit compiler was published on the

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

, and the first contributors joined the project. Later, a

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

port was created by Michael van Canneyt, five years before the Borland Kylix Pascal compiler for Linux became available. The DOS port was adapted for use in

OS/2 OS/2 is a Proprietary software, proprietary computer operating system for x86 and PowerPC based personal computers. It was created and initially developed jointly by IBM and Microsoft, under the leadership of IBM software designer Ed Iacobucci, ...

using the Eberhard Mattes eXtender (EMX) which made OS/2 the second supported compiling target. As well as Florian Klämpfl the original author, Daniël Mantione also contributed significantly to make this happen, providing the original port of the run-time library to OS/2 and EMX. The compiler improved gradually, and the DOS version migrated to the GO32v2 extender. This culminated in release 0.99.5, which was much more widely used than prior versions, and was the last release aiming only for Borland Pascal compliance; later releases added a Delphi compatibility mode. This release was also ported to systems using Motorola 68000 family (m68k) processors. With release 0.99.8 the Win32 target was added, and a start was made with incorporating some Delphi features. Stabilizing for a non- beta release began, and version 1.0 was released in July 2000. The 1.0.''x'' series was widely used, in business and education. For the 1.0.''x'' releases, the port to 68k CPU was redone, and the compiler produced stable code for several 68k

Unix-like A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...

and

AmigaOS AmigaOS is a family of proprietary native operating systems of the Amiga and AmigaOne personal computers. It was developed first by Commodore International and introduced with the launch of the first Amiga, the Amiga 1000, in 1985. Early versions ...

operating systems.

Version 2

During the stabilization of what would become 1.0.''x'', and also when porting to the

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been ...

68k systems, it was clear that the design of the code generator was far too limited in many aspects. The principal problems were that adding processors meant rewriting the code generator, and that the register allocation was based on the principle of always keeping three free registers between building blocks, which was inflexible and difficult to maintain. For these reasons, the 1.1.''x'' series branched off from the 1.0.''x'' main branch in December 1999. At first, changes were mostly clean-ups and rewrite-redesigns to all parts of the compiler. The code generator and register allocator were also rewritten. Any remaining missing Delphi compatibility was added. The work on 1.1.x continued slowly but steadily. In late 2003, a working

PowerPC PowerPC (with the backronym Performance Optimization With Enhanced RISC – Performance Computing, sometimes abbreviated as PPC) is a reduced instruction set computer (RISC) instruction set architecture (ISA) created by the 1991 Apple Inc., App ...

port became available, followed by an ARM port in summer 2004, a SPARC port in fall 2004, and an

x86-64 x86-64 (also known as x64, x86_64, AMD64, and Intel 64) is a 64-bit extension of the x86 instruction set architecture, instruction set. It was announced in 1999 and first available in the AMD Opteron family in 2003. It introduces two new ope ...

-AMD64 port in early 2004, which made the compiler available for a 64-bit platform. In November 2003, a first

beta Beta (, ; uppercase , lowercase , or cursive ; or ) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represe ...

release of the 1.1.''x'' branch was packaged and numbered 1.9.0. These were quickly followed by versions 1.9.2 and 1.9.4; the latter introduced OS X support. The work continued with version 1.9.6 (January 2005), 1.9.8 (late February 2005), 2.0.0 (May 2005), 2.0.2 (December 2005), and 2.0.4 (August 2006).

Version 2.2.x

In 2006, some of the major reworks planned for 2.2, such as the rewrite of the unit system, had still not begun, and it was decided to instead start stabilizing the already implemented features. Some of the motives for this roadmap change were the needs of the Lazarus integrated development environment project, particularly the internal linker, support for Win64, Windows CE, and OS X on x86, and related features like

DWARF Dwarf, dwarfs or dwarves may refer to: Common uses *Dwarf (folklore), a supernatural being from Germanic folklore * Dwarf, a human or animal with dwarfism Arts, entertainment, and media Fictional entities * Dwarf (''Dungeons & Dragons''), a sh ...

. After betas 2.1.2 and 2.1.4, version 2.2.0 was released in September 2007, followed by version 2.2.2 in August 2008 and version 2.2.4 in March 2009. The 2.2.''x'' series vastly improved support for the

ActiveX ActiveX is a deprecated software framework created by Microsoft that adapts its earlier Component Object Model (COM) and Object Linking and Embedding (OLE) technologies for content downloaded from a network, particularly from the World Wide W ...

and Component Object Model (COM) interface, and Object Linking and Embedding (OLE), though bugs were still being found. The delegation to interface using the implements keyword was partly implemented, but was not complete . Library support for ActiveX was also improved. Another major feature was the internal linker for Win32, Win64, and Windows CE, which greatly improved linking time and memory use, and make the compile-link-run cycle in Lazarus much faster. The efficiency for smart-linking, or dead code elimination, was also improved. Minor new features included improved DWARF (2/3) debug format support, and optimizations such as tail recursion, omission of unneeded stack frames and register-based common subexpression elimination (CSE) optimization. A first implementation of generic programming (generics) support also became available, but only experimentally.

Version 2.4.x

The 2.4.x release series had a less clear set of goals than earlier releases. The unit system rewrite was postponed again, and the branch that became 2.4 was created to keep risky commits from 2.2 to stabilize it. Mostly these risky commits were more involved improvements to the new platforms, Mac PowerPC 64, Mac x86-64, iPhone, and many fixes to the ARM and x86-64 architectures in general, as well as DWARF. Other compiler improvements included whole program optimization (WPO) and devirtualization and ARM embedded-application binary interface (EABI) support. Later, during the 2.2 cycle, a more

-like resource support (based on special sections in the binary instead of Pascal constants) was added. This feature, direly needed by Lazarus, became the main highlight of the branch. Other more minor additions were a memory manager that improved heap manager performance in threaded environments, small improvements in Delphi compatibility such as OleVariant, and improvements in interface delegation. On January 1, 2010, Free Pascal 2.4.0 was released, followed on November 13, 2010, by bug fix release 2.4.2, with support for for..in loops, sealed and abstract classes, and other changes.

Version 2.6.x

In January 2012, Free Pascal 2.6 was released. This first version from the 2.6 release series also supported Objective Pascal on OS X and iOS targets and implemented many small improvements and bug fixes. In February 2013, FPC 2.6.2 was released. It contained

NetBSD NetBSD is a free and open-source Unix-like operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was fork (software development), forked. It continues to ...

and OpenBSD releases for the first time since 1.0.10, based on fresh ports. In March 2014, the last point release in the 2.6 series, 2.6.4, was launched, featuring mostly database (fcl-db) updates.

Version 3.0.x

Version 3.0.0 was released on November 25, 2015, and was the first major release since January 1, 2012. It introduced many new language features. Version 3.0.2 was released on February 15, 2017, and includes bug fixes and minor compiler updates.
Version 3.0.4 was released on November 28, 2017.
It includes many language improvements over previous versions, including an internal linker for Executable and Linkable Format (ELF), Arm AARCH64 for iOS and Linux, a revived i8086 platform, extended libraries and much more.

Version 3.2.x

The next major release, version 3.2.0, was published on June 19, 2020. It introduced many new language features, including generic routines, standard namespaces, managed records and expanded functionality for dynamic arrays, in addition to the advent of new standard units and the support of additional platforms. Version 3.2.2 was released on May 20, 2021, and supports macOS on

AArch64 AArch64, also known as ARM64, is a 64-bit version of the ARM architecture family, a widely used set of computer processor designs. It was introduced in 2011 with the ARMv8 architecture and later became part of the ARMv9 series. AArch64 allows ...

and naming of threads. Additionally it includes bug fixes and minor compiler updates.

Targets

Free Pascal also supports byte code generation for the

Java Virtual Machine A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally descr ...

as of version 3.0.0 and targets both Oracle's Java and Google's Android JVM, although Object Pascal syntax is not fully supported. Free Pascal 3.0.0 also supports ARMHF platforms like the

Raspberry Pi Raspberry Pi ( ) is a series of small single-board computers (SBCs) developed in the United Kingdom by the Raspberry Pi Foundation in collaboration with Broadcom Inc., Broadcom. To commercialize the product and support its growing demand, the ...

, including ARMV6-EABIHF running on Raspbian. Work on 64-bit ARM has resulted in support for iOS in 3.0.0 as well. A native ARM Android target has been added, ending the formerly hacked ARM Linux target to generate native ARM libraries for Android. This makes porting Lazarus applications to Android (using Custom Drawn Interface) easier. Since FPC 2.6.2, OpenBSD and

are supported on IA32 and X86_64 architectures. A new target ''embedded'' has been added for usage without OS (ARM Cortex M and MIPS mainly). With InstantFPC it is possible to run Pascal programs, which are translated just in time, as Unix scripts or CGI back-end. Ultibo core is an embedded or bare metal development environment for Raspberry Pi. Ultibo is based on Free Pascal and developed under a modified version of Lazarus. The IDE is PC based but has been ported to Linux and Mac as well. Ultibo is an OS-less runtime and has support for most functions and allows the programmer full control over the hardware via the RTL units. The runtime implements multi-threaded, pre-emptive multitasking. The programmer can put threads on a specific CPU or let the runtime divide the load automatically or a mix of the two. Most Raspberry Pi models are supported including the A, B, A+ and B+ as well as the Raspberry Pi 2B, 3B, 4B/400/CM4 and Zero.

Integrated development environments

Like most modern compilers, Free Pascal can be used with an

(IDE). Besides independent IDEs there are also plugins to various existing IDEs Lazarus_2

* Lazarus is the most popular IDE used by Free Pascal programmers. It looks and feels similar to the Delphi IDE, and can be used to create

console Console may refer to: Computing and video games * System console, a physical device to operate a computer ** Virtual console, a user interface for multiple computer consoles on one device ** Command-line interface, a method of interacting with ...

and graphical applications, Windows services, daemons, and

web application A web application (or web app) is application software that is created with web technologies and runs via a web browser. Web applications emerged during the late 1990s and allowed for the server to dynamically build a response to the request, ...

s. Lazarus provides a cross-platform user interface framework, called Lazarus Component Library (LCL). Graphical applications created with LCL can be ported to another platform via recompiling or cross compiling. FPIDE 1

*Free Pascal has its own text-mode IDE resembling Turbo Pascal's IDE. It is made using the Free Vision framework (also included with Free Pascal), a Turbo Vision clone. In addition to many features of the Turbo Pascal IDE, it has code completion and support for multiple help file formats (HTML, Microsoft Compiled HTML Help (CHM), Information Presentation Facility (IPF). Instead of using command line tools, the IDE uses its own embedded compiler, based on the same source as the command line compiler and debugger (using libgdb or GDBMI) to provide its functionality. * Dev-Pascal is a free Windows-only IDE for Free Pascal and

GNU Pascal GNU Pascal (GPC) is a Pascal programming language, Pascal compiler composed of a frontend to GNU Compiler Collection (GCC), similar to the way Fortran and other languages were added to GCC. GNU Pascal is International Organization for Standardizat ...

, with no further development following the 2004 FPC version and the 2005 GPC version.

Bundled libraries

Apart from a compiler and an IDE, Free Pascal provides the following libraries: * Free Pascal Runtime Library (RTL): Basic low-level runtime library for general programming tasks * Free Component Library (FCL): High-level software component library for general programming tasks

Examples of software produced with Free Pascal

* Beyond Compare is a data comparison utility for Windows, OS X, and Linux. The Linux and OS X versions are compiled with Lazarus/FPC. * Cartes du Ciel is a free planetarium program for Linux, OS X, and Windows. It maps and labels most constellations, planets, and objects visible by telescope. It was fully written in Lazarus/FPC, and released under GPL. * Cheat Engine is a proprietary, source available, Freeware memory scanner, hex editor, and debugger. It can be used for cheating in computer games. Since version 6.0 it is compiled with Lazarus/FPC. * Double Commander is an open-source multi-platform two-panel orthodox file manager inspired by the Microsoft Windows-only Total Commander. * Free Pascal is written in

and assembly language, and self-compiled. * HNSKY, Hallo Northern Sky is a free planetarium program for Windows and Linux. Since version 3.4.0 written & compiled with Lazarus/FPC. * Lazarus: Free Pascal's affiliated Delphi-like software package for rapid development of graphical applications. * Morfik: Morfik WebOS AppBuilder uses Free Pascal to produce CGI binaries. * MyNotex is a free software note-taking and notes manager for Linux. * Early versions of the Nim compiler were developed in Free Pascal, before it became self-hosting in Nim. * Peazip is an open source archiver, made with Lazarus/FPC. * TorChat, previously written in Python, is now being rewritten in Free Pascal and Lazarus.

References

External links

Official websites

* FPC * Lazarus RAD IDE

General introduction

Official documentation

- by Michalis Kamburelis

Sites specialized in game development

Pascal Game Development

Pascal Gamer Magazine

– an extensive tutorial into game programming on the Game Boy Advance with Free Pascal {{Authority control Classic Mac OS software Compilers Cross-platform free software Cross-platform software Free and open source compilers Free software programmed in Pascal Linux programming tools MacOS programming tools MorphOS software Object-oriented programming languages Pascal (programming language) Pascal (programming language) compilers Pascal programming language family Pascal (programming language) software Platform-sensitive development Programming tools for Windows Self-hosting software Software using the GNU General Public License Solaris software Systems programming languages