Macros

Various common macros used throughout the codebase. More...

Files
file	cdefs.h
	Definitions for builtin attributes and compiler directives.

Macros
#define	__noreturn   __attribute__((__noreturn__))
	Identify a function that will never return.
#define	__pure   __attribute__((__const__))
	Identify a function that has no side effects other than its return, and only uses its arguments for any work.
#define	__unused   __attribute__((__unused__))
	Identify a function or variable that may be unused.
#define	__used   __attribute__((used))
	Prevent a symbol from being removed from the binary.
#define	__weak   __attribute__((weak))
	Identify a function or variable that may be overridden by another symbol.
#define	__dead2   __noreturn /* BSD compat */
	Alias for __noreturn. For BSD compatibility.
#define	__pure2   __pure /* ditto */
	Alias for __pure. For BSD compatibility.
#define	__likely(exp)   __builtin_expect(!!(exp), 1)
	Directive to inform the compiler the condition is in the likely path.
#define	__unlikely(exp)   __builtin_expect(!!(exp), 0)
	Directive to inform the compiler the condition is in the unlikely path.
#define	__deprecated   __attribute__((deprecated))
	Mark something as deprecated. This should be used to warn users that a function/type/etc will be removed in a future version of KOS.
#define	__depr(m)   __attribute__((deprecated(m)))
	Mark something as deprecated, with an informative message. This should be used to warn users that a function/type/etc will be removed in a future version of KOS and to suggest an alternative that they can use instead.
#define	__printflike(fmtarg, firstvararg)    __attribute__((__format__ (__printf__, fmtarg, firstvararg)))
	Identify a function as accepting formatting like printf().
#define	__scanflike(fmtarg, firstvararg)    __attribute__((__format__ (__scanf__, fmtarg, firstvararg)))
	Identify a function as accepting formatting like scanf().
#define	__fallthrough   /* Fall through */
#define	__always_inline   inline __attribute__((__always_inline__))
	Ask the compiler to always inline a given function.
#define	__no_inline   __attribute__((__noinline__))
	Ask the compiler to never inline a given function.
#define	__RESTRICT
#define	__extension__

Detailed Description

Various common macros used throughout the codebase.

Macro Definition Documentation

__always_inline

#define __always_inline   inline __attribute__((__always_inline__))

Ask the compiler to always inline a given function.

__dead2

#define __dead2   __noreturn /* BSD compat */

Alias for __noreturn. For BSD compatibility.

__depr

#define __depr

(

m

)

__attribute__((deprecated(m)))

Mark something as deprecated, with an informative message. This should be used to warn users that a function/type/etc will be removed in a future version of KOS and to suggest an alternative that they can use instead.

Parameters

m	A string literal that is included with the warning message at compile time.

__deprecated

#define __deprecated   __attribute__((deprecated))

Mark something as deprecated. This should be used to warn users that a function/type/etc will be removed in a future version of KOS.

__extension__

#define __extension__

__fallthrough

#define __fallthrough   /* Fall through */

__likely

#define __likely

(

exp

)

__builtin_expect(!!(exp), 1)

Directive to inform the compiler the condition is in the likely path.

This can be used around conditionals or loops to help inform the compiler which path to optimize for as the common-case.

Parameters

exp	Boolean expression which expected to be true.

See also

__unlikely()

__no_inline

#define __no_inline   __attribute__((__noinline__))

Ask the compiler to never inline a given function.

__noreturn

#define __noreturn   __attribute__((__noreturn__))

Identify a function that will never return.

__printflike

#define __printflike	(		fmtarg,
			firstvararg
	)		__attribute__((__format__ (__printf__, fmtarg, firstvararg)))

Identify a function as accepting formatting like printf().

Using this macro allows GCC to typecheck calls to printf-like functions, which can aid in finding mistakes.

Parameters

fmtarg	The argument number (1-based) of the format string.
firstvararg	The argument number of the first vararg (the ...).

__pure

#define __pure   __attribute__((__const__))

Identify a function that has no side effects other than its return, and only uses its arguments for any work.

__pure2

#define __pure2   __pure /* ditto */

Alias for __pure. For BSD compatibility.

__RESTRICT

#define __RESTRICT

__scanflike

#define __scanflike	(		fmtarg,
			firstvararg
	)		__attribute__((__format__ (__scanf__, fmtarg, firstvararg)))

Identify a function as accepting formatting like scanf().

Using this macro allows GCC to typecheck calls to scanf-like functions, which can aid in finding mistakes.

Parameters

fmtarg	The argument number (1-based) of the format string.
firstvararg	The argument number of the first vararg (the ...).

__unlikely

#define __unlikely

(

exp

)

__builtin_expect(!!(exp), 0)

Directive to inform the compiler the condition is in the unlikely path.

This can be used around conditionals or loops to help inform the compiler which path to optimize against as the infrequent-case.

Parameters

exp	Boolean expression which is expected to be false.

See also

__likely()

__unused

#define __unused   __attribute__((__unused__))

Identify a function or variable that may be unused.

__used

#define __used   __attribute__((used))

Prevent a symbol from being removed from the binary.

__weak

#define __weak   __attribute__((weak))

Identify a function or variable that may be overridden by another symbol.