DJGPP

Last updated

DJGPP
Developer(s) DJ Delorie
Stable release
2.05 / November 3, 2015;9 years ago (2015-11-03) [1]
Repository
Operating system DOS and 32-bit Windows
Type Compiler
License GNU GPL
Website www.delorie.com/djgpp

DJ's GNU Programming Platform (DJGPP) [2] is a software development suite for Intel 80386-level and above, IBM PC compatibles which supports DOS operating systems. It is guided by DJ Delorie, who began the project in 1989. It is a port of the GNU Compiler Collection (GCC), and mostly GNU utilities such as Bash, find, tar, ls, GAWK, sed, and ld to DOS Protected Mode Interface (DPMI). Supported languages include C, C++, Objective-C/C++, Ada, Fortran, and Pascal. It was originally called DJGCC, and was later renamed from DJGCC to DJGPP when C++ support was added, though the "PP" was said to stand for "Programming Platform" rather than "Plus Plus". [3]

Contents

Overview

The compiler generates 32-bit code, which runs natively in 32-bit protected mode while switching back to 16-bit DOS calls for basic OS support. However, unlike the Open Watcom C/C++ compiler, it is not a zero-based flat model due to preferring NULL pointer protection for better stability. It is currently based upon a variant of the COFF format. It can access up to 4 GB of RAM in pure DOS when using a suitable DPMI host (e.g., CWSDPMI r7 or HDPMI32).

As of August 2020, main components of DJGPP 2 include:

It is also possible to use DJGPP to cross-compile software to DOS, for example on UNIX / Linux. Both the DJGPP libraries and the programs can be compiled this way, linked and then deployed to machines with DOS or DOS emulators.

Compatibility

DJGPP presents the programmer an interface which is compatible with the ANSI C and C99 standards, DOS APIs, and an older POSIX-like environment. Compiled binaries are long filename (LFN) aware and can handle such names under most 32-bit Windows by default, but they cannot use the Win16 or Win32 APIs that graphical programs on Windows need. [4] terminate-and-stay-resident (TSR) programs to support LFNs under plain DOS or Windows NT 4 are available.

While DJGPP runs in 32-bit protected mode, its stub and library heavily rely on many 16-bit DOS and BIOS calls. Because the x86-64 versions of Windows lack support for 16-bit programs, [5] [6] there is no NTVDM, and DJGPP applications cannot be run. Under x86-64 systems these applications function only through emulation (e.g. DOSBox), x86 virtualization (e.g. VirtualBox), or similar (e.g. Linux's DOSEMU). This problem arises because in long mode x86-64 processors do not support the virtual 8086 mode used to run 16-bit code in IA-32 processors. Newer x86 CPUs with VT-x do support paged real mode and unrestricted guest mode execution.

See also

Related Research Articles

<span class="mw-page-title-main">Cygwin</span> Unix-like environment for Windows

Cygwin is a free and open-source Unix-like environment and command-line interface (CLI) for Microsoft Windows. The project also provides a software repository containing many open-source packages. Cygwin allows source code for Unix-like operating systems to be compiled and run on Windows. Cygwin provides native integration of Windows-based applications.

Real mode, also called real address mode, is an operating mode of all x86-compatible CPUs. The mode gets its name from the fact that addresses in real mode always correspond to real locations in memory. Real mode is characterized by a 20-bit segmented memory address space and unlimited direct software access to all addressable memory, I/O addresses and peripheral hardware. Real mode provides no support for memory protection, multitasking, or code privilege levels.

<span class="mw-page-title-main">Windows API</span> Microsofts core set of application programming interfaces on Windows

The Windows API, informally WinAPI, is the foundational application programming interface (API) that allows a computer program to access the features of the Microsoft Windows operating system in which the program is running. Programs access API functionality via dynamic-link library (DLL) technology.

A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a PC but generates code that runs on Android devices is a cross compiler.

<span class="mw-page-title-main">MinGW</span> Free and open-source software for developing applications in Microsoft Windows

MinGW, formerly mingw32, is a free and open source software development environment to create Microsoft Windows applications.

<span class="mw-page-title-main">Free Pascal</span> Free compiler and IDE for Pascal and ObjectPascal

Free Pascal Compiler (FPC) is a compiler for the closely related programming-language dialects Pascal and Object Pascal. It is free software released under the GNU General Public License, with exception clauses that allow static linking against its runtime libraries and packages for any purpose in combination with any other software license.

The Microsoft Macro Assembler (MASM) is an x86 assembler that uses the Intel syntax for MS-DOS and Microsoft Windows. Beginning with MASM 8.0, there are two versions of the assembler: One for 16-bit & 32-bit assembly sources, and another (ML64) for 64-bit sources only.

<span class="mw-page-title-main">DOSEMU</span> DOS compatibility layer for Linux

DOSEMU, stylized as dosemu, is a compatibility layer software package that enables DOS operating systems and application software to run atop Linux on x86-based PCs.

A DOS extender is a computer software program running under DOS that enables software to run in a protected mode environment even though the host operating system is only capable of operating in real mode.

<span class="mw-page-title-main">Watcom C/C++</span>

Watcom C/C++ is an integrated development environment (IDE) product from Watcom International Corporation for the C, C++, and Fortran programming languages. Watcom C/C++ was a commercial product until it was discontinued, then released under the Sybase Open Watcom Public License as Open Watcom C/C++. It features tools for developing and debugging code for DOS, OS/2, Windows, and Linux operating systems, which are based upon 16-bit x86, 32-bit IA-32, or 64-bit x86-64 compatible processors.

In computer security, executable-space protection marks memory regions as non-executable, such that an attempt to execute machine code in these regions will cause an exception. It makes use of hardware features such as the NX bit, or in some cases software emulation of those features. However, technologies that emulate or supply an NX bit will usually impose a measurable overhead while using a hardware-supplied NX bit imposes no measurable overhead.

In C and related programming languages, long double refers to a floating-point data type that is often more precise than double precision though the language standard only requires it to be at least as precise as double. As with C's other floating-point types, it may not necessarily map to an IEEE format.

process.h is a C header file which contains function declarations and macros used in working with threads and processes. Most C compilers that target DOS, Windows 3.1x, Win32, OS/2, Novell NetWare or DOS extenders supply this header and the library functions in their C library. Neither the header file nor most of the functions are defined by either the ANSI/ISO C standard or by POSIX.

conio.h is a C header file used mostly by MS-DOS compilers to provide console input/output. It is not part of the C standard library or ISO C, nor is it defined by POSIX.

EMX is a programming environment for MS-DOS and OS/2. It allows creating and executing of 32-bit mode applications, presenting a POSIX API and, on OS/2, access to the OS/2 APIs.

Open Watcom Assembler or WASM is an x86 assembler produced by Watcom, based on the Watcom Assembler found in Watcom C/C++ compiler and Watcom FORTRAN 77. Further development is being done on the 32- and 64-bit JWASM project, which more closely matches the syntax of Microsoft's assembler.

Bionic is an implementation of the C standard library, developed by Google for its Android operating system. It differs from the GNU C Library (glibc) in being designed for devices with less memory and processor power than a typical Linux system. It is a combination of new code and code from FreeBSD, NetBSD, and OpenBSD released under a BSD license, rather than glibc, which uses the GNU Lesser General Public License. This difference was important in the early days of Android, when static linking was common, and since Bionic has its own application binary interface, it cannot be replaced by a different libc without breaking all existing apps.

Mingw-w64 is a free and open-source suite of development tools that generate Portable Executable (PE) binaries for Microsoft Windows. It was forked in 2005–2010 from MinGW.

References

  1. "Announce: DJGPP V2.05 Released". Newsgroup:  comp.os.msdos.djgpp. 3 November 2015.
  2. Eli Zaretskii (Jul 1999). "The DJGPP Project" . Retrieved 20 Jul 2009.
  3. "The history of djgpp".
  4. Wall, Kurt; Von Hagen, William (2004). The Definitive Guide to GCC. Apress. pp. 47–48. ISBN   9781590591093. Another popular, though aging, GCC-based development system is DJGPP, D.J.[sic] Delorie's free 32-bit development environment for DOS systems.
  5. "Guide: What is DJGPP?" . Retrieved November 22, 2015. The target hardware platform for DJGPP programs is a PC platform ... running DOS ... or a DOS-compatible operating system DJGPP programs run under Windows' "dos prompt" boxes.
  6. Microsoft (11 Oct 2007). "List of limitations in 64-Bit Windows". Archived from the original on 20 April 2010. Retrieved 20 Apr 2010. 16-bit MS-DOS and Microsoft Windows 3.x utilities will not start. If you attempt to start such a program, you receive a "Program.exe is not a valid Win32 application" error message.