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Add __offsetof, __rangeof and __containerof to sys/cdefs.h

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Import and adapt from FreeBSD.
This commit is contained in:
Guillem Jover 2014-11-01 00:21:30 +01:00
parent 0e4e3ab269
commit 3267114483
1 changed files with 41 additions and 0 deletions
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41
include/bsd/sys/cdefs.h
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@ -114,6 +114,47 @@
# define __bounded__(x, y, z)
#endif
/*
* We define this here since <stddef.h>, <sys/queue.h>, and <sys/types.h>
* require it.
*/
#ifndef __offsetof
# if LIBBSD_GCC_VERSION >= 0x0401
# define __offsetof(type, field) __builtin_offsetof(type, field)
# else
# ifndef __cplusplus
# define __offsetof(type, field) \
((__size_t)(__uintptr_t)((const volatile void *)&((type *)0)->field))
# else
# define __offsetof(type, field) \
(__offsetof__ (reinterpret_cast <__size_t> \
(&reinterpret_cast <const volatile char &> \
(static_cast<type *> (0)->field))))
# endif
# endif
#endif
#define __rangeof(type, start, end) \
(__offsetof(type, end) - __offsetof(type, start))
/*
* Given the pointer x to the member m of the struct s, return
* a pointer to the containing structure. When using GCC, we first
* assign pointer x to a local variable, to check that its type is
* compatible with member m.
*/
#ifndef __containerof
# if LIBBSD_GCC_VERSION >= 0x0301
# define __containerof(x, s, m) ({ \
const volatile __typeof(((s *)0)->m) *__x = (x); \
__DEQUALIFY(s *, (const volatile char *)__x - __offsetof(s, m)); \
})
# else
# define __containerof(x, s, m) \
__DEQUALIFY(s *, (const volatile char *)(x) - __offsetof(s, m))
# endif
#endif
#ifndef __RCSID
# define __RCSID(x)
#endif