The C Preprocessor - Nonstandard Predefined

Go to the previous, next section.

Nonstandard Predefined Macros

The C preprocessor normally has several predefined macros that vary between machines because their purpose is to indicate what type of system and machine is in use or being targetted. Some nonstandard predefined macros describe the operating system in use, with more or less specificity. For example, unix, BSD, mc68000. These predefined symbols are not only nonstandard, they are contrary to the ANSI standard because their names do not start with underscores.

GNU C offers a series of symbols for this purpose, whose names are made by adding `__' at the beginning and end of the targetted machine name specified with the `-b machine' switch. Thus, the symbol __vax__ will be defined when the `-b vax' switch is used.

__alpha__ DEC Alpha architecture.
__arc__ Argonaut ARC processor.
__amigaos__ AmigaOS.
__apple__ Apple Macintosh Mac OS.
__arm__ ARM-family processors.
__avr__ ATMEL AVR-family micro controllers. These are used in embedded applications.
__beos__ BeOS.
__blackfin__ The Blackfin processor, an Analog Devices DSP.
__bsd__ BSD.
__cris__ CRIS is the CPU architecture in Axis Communications ETRAX system-on-a-chip series. These are used in embedded applications.
__crx__ The CRX CompactRISC architecture is a low-power 32-bit architecture with fast context switching and architectural extensibility features.
__dragonfly__ DragonFly.
__dos__ MSDOS, PCDOS, DRDOS.
__h8300__ Renesas H8/300 series of processors.
__i86__ Intel x86 processors.
__i286__ Intel i286 processor.
__i386__ Intel i386 processor.
__i486__ Intel i486 processor.
__i586__ Intel Pentium™ processor.
__iq2000__ Vitesse IQ2000 processors. These are used in embedded applications./TD>
__linux__ Linux.
__m32c__ Renesas M32C processor. This configuration is intended for embedded systems.
__m32r__ Renesas M32R processor. This configuration is intended for embedded systems.
__m6811__ Motorola 68HC11 family micro controllers. These are used in embedded applications.
__m6812__ Motorola 68HC12 family micro controllers. These are used in embedded applications.
__m68k__ Motorola M680x0 and ColdFire processors.
__m68000__ Motorola M68000 processor.
__m68010__ Motorola M68010 processor.
__m68020__ Motorola M68020 processor.
__m68030__ Motorola M68030 processor.
__m68040__ Motorola M68040 processor.
__m68060__ Motorola M68060 processor.
__macos__ Macintosh Max OS.
__mips__ MIPS system.
__ns32k__ National Semiconductor 320xx processors.
__os2__ IBM OS/2
__powerpc__ PowerPC system.
__riscos__ RISC OS.
__s390__ S/390 system.
__sequent__ DYNIX/ptx.
__sparc__ Sun SPARC CPUs.
__sun__ Sun systems.
__sparc64__ 64-bit Sun SPARC CPUs.
__unicos__ Cray UniCOS.
__unix__ UNIX or Unix-alike systems.
__vax__ DEC VAX.
__win32__ Microsoft Windows (32-bit)
__xtensa__ Embedded Xtensa systems

Go to the previous, next section.

`__alpha__`		DEC Alpha architecture.
`__arc__`		Argonaut ARC processor.
`__amigaos__`		AmigaOS.
`__apple__`		Apple Macintosh Mac OS.
`__arm__`		ARM-family processors.
`__avr__`		ATMEL AVR-family micro controllers. These are used in embedded applications.
`__beos__`		BeOS.
`__blackfin__`		The Blackfin processor, an Analog Devices DSP.
`__bsd__`		BSD.
`__cris__`		CRIS is the CPU architecture in Axis Communications ETRAX system-on-a-chip series. These are used in embedded applications.
`__crx__`		The CRX CompactRISC architecture is a low-power 32-bit architecture with fast context switching and architectural extensibility features.
`__dragonfly__`		DragonFly.
`__dos__`		MSDOS, PCDOS, DRDOS.
`__h8300__`		Renesas H8/300 series of processors.
`__i86__`		Intel x86 processors.
`__i286__`		Intel i286 processor.
`__i386__`		Intel i386 processor.
`__i486__`		Intel i486 processor.
`__i586__`		Intel Pentium™ processor.
`__iq2000__`		Vitesse IQ2000 processors. These are used in embedded applications./TD>
`__linux__`		Linux.
`__m32c__`		Renesas M32C processor. This configuration is intended for embedded systems.
`__m32r__`		Renesas M32R processor. This configuration is intended for embedded systems.
`__m6811__`		Motorola 68HC11 family micro controllers. These are used in embedded applications.
`__m6812__`		Motorola 68HC12 family micro controllers. These are used in embedded applications.
`__m68k__`		Motorola M680x0 and ColdFire processors.
`__m68000__`		Motorola M68000 processor.
`__m68010__`		Motorola M68010 processor.
`__m68020__`		Motorola M68020 processor.
`__m68030__`		Motorola M68030 processor.
`__m68040__`		Motorola M68040 processor.
`__m68060__`		Motorola M68060 processor.
`__macos__`		Macintosh Max OS.
`__mips__`		MIPS system.
`__ns32k__`		National Semiconductor 320xx processors.
`__os2__`		IBM OS/2
`__powerpc__`		PowerPC system.
`__riscos__`		RISC OS.
`__s390__`		S/390 system.
`__sequent__`		DYNIX/ptx.
`__sparc__`		Sun SPARC CPUs.
`__sun__`		Sun systems.
`__sparc64__`		64-bit Sun SPARC CPUs.
`__unicos__`		Cray UniCOS.
`__unix__`		UNIX or Unix-alike systems.
`__vax__`		DEC VAX.
`__win32__`		Microsoft Windows (32-bit)
`__xtensa__`		Embedded Xtensa systems