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/* SPDX-License-Identifier: MIT */
/**
* utils.h - useful macros for compile-time magic
*
* Inspired by similar macros in the Linux Kernel.
*
* Copyright (c) 2023 - Yaroslav de la Peña Smirnov
*/
#ifndef CWARE_UTILS_H
#define CWARE_UTILS_H
#include <stddef.h>
#ifndef static_assert
#define static_assert(exp, msg) _Static_assert(exp, msg)
#endif
/**
* BUILD_BUG_ON_ZERO - throws compilation error if true, expressions returns 0.
* @cond: condition
*
* Force a compilation error if condition is true, but also produce a
* result (of value 0 and type int), so the expression can be used
* e.g. in a structure initializer (or where-ever else comma expressions
* aren't permitted).
*/
#define BUILD_BUG_ON_ZERO(cond) ((int)(sizeof(struct { int : (-!!(cond)); })))
#define same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
#define container_of(ptr, T, member) \
({ \
static_assert(same_type(*(ptr), ((T *)0)->member) \
|| same_type(*(ptr), void), \
"type mismatch in container_of()"); \
(T *)((void *)(ptr)-offsetof(T, member)); \
})
/**
* __ASSERT_IS_ARRAY - throw a compilation error if @arr is not an array.
* @arr: variable to check.
*/
#define __ASSERT_IS_ARRAY(arr) BUILD_BUG_ON_ZERO(same_type((arr), &(arr)[0]))
/**
* ARRAY_SIZE - return the number of elements in @arr.
* @arr: array of any type.
*/
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(*arr) + __ASSERT_IS_ARRAY(arr))
#endif
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