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/****************************************************************************
* include/stddef.h
*
* Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 NuttX 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 COPYRIGHT HOLDERS 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
* COPYRIGHT OWNER 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.
*
****************************************************************************/
#ifndef __INCLUDE_STDDEF_H
#define __INCLUDE_STDDEF_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <sys/types.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* The <stddef.h> header shall define the following macros:
*
* NULL
* The null pointer constant.
*
* NOTE: Currently the definition of NULL is in sys/types.h but should
* be moved here sometime.
*
* offsetof(type, member-designator)
* Integer constant expression of type size_t, the value of which is the
* offset in bytes to the structure member (member-designator), from the
* beginning of its structure (type).
*
* NOTE: This version of offsetof() depends on behaviors that could be
* undefined for some compilers. It would be better to use a builtin
* function if one exists.
*
* Reference: Opengroup.org
*/
#define offsetof(a, b) ((size_t)(&(((a *)(0))->b)))
/****************************************************************************
* Type Definitions
****************************************************************************/
/* The <stddef.h> header shall define the following types:
*
* ptrdiff_t
* Signed integer type of the result of subtracting two pointers.
*
* wchar_t
* Integer type whose range of values can represent distinct wide-character
* codes for all members of the largest character set specified among the
* locales supported by the compilation environment: the null character has
* the code value 0 and each member of the portable character set has a
* code value equal to its value when used as the lone character in an
* integer character constant.
*
* size_t
* Unsigned integer type of the result of the sizeof operator.
*
* NOTE: Currently the type definitions of ptrdiff_t, wchar_t, and size_t are
* in sys/types.h but should be moved here sometime.
*
* The implementation shall support one or more programming environments in
* which the widths of ptrdiff_t, size_t, and wchar_t are no greater than the
* width of type long. The names of these programming environments can be
* obtained using the confstr() function or the getconf utility.
*
* Reference: Opengroup.org
*/
#endif /* __INCLUDE_STDDEF_H */