FreeBSD/Linux Kernel Cross Reference
sys/sys/cdefs.h

     /*      $NetBSD: cdefs.h,v 1.69 2008/08/17 00:23:02 gmcgarry Exp $      */
     
     /*
      * Copyright (c) 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * Berkeley Software Design, Inc.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)cdefs.h     8.8 (Berkeley) 1/9/95
     */
    
    #ifndef _SYS_CDEFS_H_
    #define _SYS_CDEFS_H_
    
    /*
     * Macro to test if we're using a GNU C compiler of a specific vintage
     * or later, for e.g. features that appeared in a particular version
     * of GNU C.  Usage:
     *
     *      #if __GNUC_PREREQ__(major, minor)
     *      ...cool feature...
     *      #else
     *      ...delete feature...
     *      #endif
     */
    #ifdef __GNUC__
    #define __GNUC_PREREQ__(x, y)                                           \
            ((__GNUC__ == (x) && __GNUC_MINOR__ >= (y)) ||                  \
             (__GNUC__ > (x)))
    #else
    #define __GNUC_PREREQ__(x, y)   0
    #endif
    
    #include <machine/cdefs.h>
    #ifdef __ELF__
    #include <sys/cdefs_elf.h>
    #else
    #include <sys/cdefs_aout.h>
    #endif
    
    #if defined(__cplusplus)
    #define __BEGIN_DECLS           extern "C" {
    #define __END_DECLS             }
    #define __static_cast(x,y)      static_cast<x>(y)
    #else
    #define __BEGIN_DECLS
    #define __END_DECLS
    #define __static_cast(x,y)      (x)y
    #endif
    
    /*
     * The __CONCAT macro is used to concatenate parts of symbol names, e.g.
     * with "#define OLD(foo) __CONCAT(old,foo)", OLD(foo) produces oldfoo.
     * The __CONCAT macro is a bit tricky -- make sure you don't put spaces
     * in between its arguments.  __CONCAT can also concatenate double-quoted
     * strings produced by the __STRING macro, but this only works with ANSI C.
     */
    
    #define ___STRING(x)    __STRING(x)
    #define ___CONCAT(x,y)  __CONCAT(x,y)
    
    #if __STDC__ || defined(__cplusplus)
    #define __P(protos)     protos          /* full-blown ANSI C */
    #define __CONCAT(x,y)   x ## y
    #define __STRING(x)     #x
    
    #define __const         const           /* define reserved names to standard */
    #define __signed        signed
    #define __volatile      volatile
    #if defined(__cplusplus) || defined(__PCC__)
    #define __inline        inline          /* convert to C++/C99 keyword */
    #else
    #if !defined(__GNUC__) && !defined(__lint__)
    #define __inline                        /* delete GCC keyword */
   #endif /* !__GNUC__  && !__lint__ */
   #endif /* !__cplusplus */
   
   #else   /* !(__STDC__ || __cplusplus) */
   #define __P(protos)     ()              /* traditional C preprocessor */
   #define __CONCAT(x,y)   x/**/y
   #define __STRING(x)     "x"
   
   #ifndef __GNUC__
   #define __const                         /* delete pseudo-ANSI C keywords */
   #define __inline
   #define __signed
   #define __volatile
   #endif  /* !__GNUC__ */
   
   /*
    * In non-ANSI C environments, new programs will want ANSI-only C keywords
    * deleted from the program and old programs will want them left alone.
    * Programs using the ANSI C keywords const, inline etc. as normal
    * identifiers should define -DNO_ANSI_KEYWORDS.
    */
   #ifndef NO_ANSI_KEYWORDS
   #define const           __const         /* convert ANSI C keywords */
   #define inline          __inline
   #define signed          __signed
   #define volatile        __volatile
   #endif /* !NO_ANSI_KEYWORDS */
   #endif  /* !(__STDC__ || __cplusplus) */
   
   /*
    * Used for internal auditing of the NetBSD source tree.
    */
   #ifdef __AUDIT__
   #define __aconst        __const
   #else
   #define __aconst
   #endif
   
   /*
    * The following macro is used to remove const cast-away warnings
    * from gcc -Wcast-qual; it should be used with caution because it
    * can hide valid errors; in particular most valid uses are in
    * situations where the API requires it, not to cast away string
    * constants. We don't use *intptr_t on purpose here and we are
    * explicit about unsigned long so that we don't have additional
    * dependencies.
    */
   #define __UNCONST(a)    ((void *)(unsigned long)(const void *)(a))
   
   /*
    * The following macro is used to remove the volatile cast-away warnings
    * from gcc -Wcast-qual; as above it should be used with caution
    * because it can hide valid errors or warnings.  Valid uses include
    * making it possible to pass a volatile pointer to memset().
    * For the same reasons as above, we use unsigned long and not intptr_t.
    */
   #define __UNVOLATILE(a) ((void *)(unsigned long)(volatile void *)(a))
   
   /*
    * GCC2 provides __extension__ to suppress warnings for various GNU C
    * language extensions under "-ansi -pedantic".
    */
   #if !__GNUC_PREREQ__(2, 0)
   #define __extension__           /* delete __extension__ if non-gcc or gcc1 */
   #endif
   
   /*
    * GCC1 and some versions of GCC2 declare dead (non-returning) and
    * pure (no side effects) functions using "volatile" and "const";
    * unfortunately, these then cause warnings under "-ansi -pedantic".
    * GCC2 uses a new, peculiar __attribute__((attrs)) style.  All of
    * these work for GNU C++ (modulo a slight glitch in the C++ grammar
    * in the distribution version of 2.5.5).
    */
   #if !__GNUC_PREREQ__(2, 0)
   #define __attribute__(x)
   #endif
   
   #if __GNUC_PREREQ__(2, 5)
   #define __dead          __attribute__((__noreturn__))
   #elif defined(__GNUC__)
   #define __dead          __volatile
   #else
   #define __dead
   #endif
   
   #if __GNUC_PREREQ__(2, 96)
   #define __pure          __attribute__((__pure__))
   #elif defined(__GNUC__)
   #define __pure          __const
   #else
   #define __pure
   #endif
   
   #if __GNUC_PREREQ__(3, 0)
   #define __noinline      __attribute__((__noinline__))
   #else
   #define __noinline      /* nothing */
   #endif
   
   #if __GNUC_PREREQ__(2, 7)
   #define __unused        __attribute__((__unused__))
   #else
   #define __unused        /* delete */
   #endif
   
   #if __GNUC_PREREQ__(3, 1)
   #define __used          __attribute__((__used__))
   #else
   #define __used          __unused
   #endif
   
   #if __GNUC_PREREQ__(2, 7)
   #define __packed        __attribute__((__packed__))
   #define __aligned(x)    __attribute__((__aligned__(x)))
   #define __section(x)    __attribute__((__section__(x)))
   #elif defined(__PCC__)
   #define __packed        _Pragma("packed")
   #define __aligned(x)    _Pragma("aligned " #x)
   #define __section(x)    _Pragma("section " ## x)
   #elif defined(__lint__)
   #define __packed        /* delete */
   #define __aligned(x)    /* delete */
   #define __section(x)    /* delete */
   #else
   #define __packed        error: no __packed for this compiler
   #define __aligned(x)    error: no __aligned for this compiler
   #define __section(x)    error: no __section for this compiler
   #endif
   
   /*
    * C99 defines the restrict type qualifier keyword, which was made available
    * in GCC 2.92.
    */
   #if defined(__lint__)
   #define __restrict      /* delete __restrict when not supported */
   #elif __STDC_VERSION__ >= 199901L
   #define __restrict      restrict
   #elif !__GNUC_PREREQ__(2, 92)
   #define __restrict      /* delete __restrict when not supported */
   #endif
   
   /*
    * C99 defines __func__ predefined identifier, which was made available
    * in GCC 2.95.
    */
   #if !(__STDC_VERSION__ >= 199901L)
   #if __GNUC_PREREQ__(2, 6)
   #define __func__        __PRETTY_FUNCTION__
   #elif __GNUC_PREREQ__(2, 4)
   #define __func__        __FUNCTION__
   #else
   #define __func__        ""
   #endif
   #endif /* !(__STDC_VERSION__ >= 199901L) */
   
   #if defined(_KERNEL)
   #if defined(NO_KERNEL_RCSIDS)
   #undef __KERNEL_RCSID
   #define __KERNEL_RCSID(_n, _s)          /* nothing */
   #endif /* NO_KERNEL_RCSIDS */
   #endif /* _KERNEL */
   
   #if !defined(_STANDALONE) && !defined(_KERNEL)
   #if defined(__GNUC__) || defined(__PCC__)
   #define __RENAME(x)     ___RENAME(x)
   #else
   #ifdef __lint__
   #define __RENAME(x)     __symbolrename(x)
   #else
   #error "No function renaming possible"
   #endif /* __lint__ */
   #endif /* __GNUC__ */
   #else /* _STANDALONE || _KERNEL */
   #define __RENAME(x)     no renaming in kernel or standalone environment
   #endif
   
   /*
    * A barrier to stop the optimizer from moving code or assume live
    * register values. This is gcc specific, the version is more or less
    * arbitrary, might work with older compilers.
    */
   #if __GNUC_PREREQ__(2, 95)
   #define __insn_barrier()        __asm __volatile("":::"memory")
   #else
   #define __insn_barrier()        /* */
   #endif
   
   /*
    * GNU C version 2.96 adds explicit branch prediction so that
    * the CPU back-end can hint the processor and also so that
    * code blocks can be reordered such that the predicted path
    * sees a more linear flow, thus improving cache behavior, etc.
    *
    * The following two macros provide us with a way to use this
    * compiler feature.  Use __predict_true() if you expect the expression
    * to evaluate to true, and __predict_false() if you expect the
    * expression to evaluate to false.
    *
    * A few notes about usage:
    *
    *      * Generally, __predict_false() error condition checks (unless
    *        you have some _strong_ reason to do otherwise, in which case
    *        document it), and/or __predict_true() `no-error' condition
    *        checks, assuming you want to optimize for the no-error case.
    *
    *      * Other than that, if you don't know the likelihood of a test
    *        succeeding from empirical or other `hard' evidence, don't
    *        make predictions.
    *
    *      * These are meant to be used in places that are run `a lot'.
    *        It is wasteful to make predictions in code that is run
    *        seldomly (e.g. at subsystem initialization time) as the
    *        basic block reordering that this affects can often generate
    *        larger code.
    */
   #if __GNUC_PREREQ__(2, 96)
   #define __predict_true(exp)     __builtin_expect((exp) != 0, 1)
   #define __predict_false(exp)    __builtin_expect((exp) != 0, 0)
   #else
   #define __predict_true(exp)     (exp)
   #define __predict_false(exp)    (exp)
   #endif
   
   /*
    * Macros for manipulating "link sets".  Link sets are arrays of pointers
    * to objects, which are gathered up by the linker.
    *
    * Object format-specific code has provided us with the following macros:
    *
    *      __link_set_add_text(set, sym)
    *              Add a reference to the .text symbol `sym' to `set'.
    *
    *      __link_set_add_rodata(set, sym)
    *              Add a reference to the .rodata symbol `sym' to `set'.
    *
    *      __link_set_add_data(set, sym)
    *              Add a reference to the .data symbol `sym' to `set'.
    *
    *      __link_set_add_bss(set, sym)
    *              Add a reference to the .bss symbol `sym' to `set'.
    *
    *      __link_set_decl(set, ptype)
    *              Provide an extern declaration of the set `set', which
    *              contains an array of the pointer type `ptype'.  This
    *              macro must be used by any code which wishes to reference
    *              the elements of a link set.
    *
    *      __link_set_start(set)
    *              This points to the first slot in the link set.
    *
    *      __link_set_end(set)
    *              This points to the (non-existent) slot after the last
    *              entry in the link set.
    *
    *      __link_set_count(set)
    *              Count the number of entries in link set `set'.
    *
    * In addition, we provide the following macros for accessing link sets:
    *
    *      __link_set_foreach(pvar, set)
    *              Iterate over the link set `set'.  Because a link set is
    *              an array of pointers, pvar must be declared as "type **pvar",
    *              and the actual entry accessed as "*pvar".
    *
    *      __link_set_entry(set, idx)
    *              Access the link set entry at index `idx' from set `set'.
    */
   #define __link_set_foreach(pvar, set)                                   \
           for (pvar = __link_set_start(set); pvar < __link_set_end(set); pvar++)
   
   #define __link_set_entry(set, idx)      (__link_set_begin(set)[idx])
   
   /*
    * Return the number of elements in a statically-allocated array,
    * __x.
    */
   #define __arraycount(__x)       (sizeof(__x) / sizeof(__x[0]))
   
   /* __BIT(n): nth bit, where __BIT(0) == 0x1. */
   #define __BIT(__n)      \
           (((__n) >= NBBY * sizeof(uintmax_t)) ? 0 : ((uintmax_t)1 << (__n)))
   
   /* __BITS(m, n): bits m through n, m < n. */
   #define __BITS(__m, __n)        \
           ((__BIT(MAX((__m), (__n)) + 1) - 1) ^ (__BIT(MIN((__m), (__n))) - 1))
   
   /* find least significant bit that is set */
   #define __LOWEST_SET_BIT(__mask) ((((__mask) - 1) & (__mask)) ^ (__mask))
   
   #define __PRIuBIT       PRIuMAX
   #define __PRIuBITS      __PRIuBIT
   
   #define __PRIxBIT       PRIxMAX
   #define __PRIxBITS      __PRIxBIT
   
   #define __SHIFTOUT(__x, __mask) (((__x) & (__mask)) / __LOWEST_SET_BIT(__mask))
   #define __SHIFTIN(__x, __mask) ((__x) * __LOWEST_SET_BIT(__mask))
   #define __SHIFTOUT_MASK(__mask) __SHIFTOUT((__mask), (__mask))
   
   #endif /* !_SYS_CDEFS_H_ */

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