util: provide IS_ARRAY_ELEMENT, ARRAY_INDEX, ARRAY_INDEX_FLOOR

#endif /* __cplusplus */

/**

 * @brief Whether @p ptr is an element of @p array

 *

 * This macro can be seen as a slightly stricter version of @ref PART_OF_ARRAY

 * in that it also ensures that @p ptr is aligned to an array-element boundary

 * of @p array.

 *

 * In C, passing a pointer as @p array causes a compile error.

 *

 * @param array the array in question

 * @param ptr the pointer to check

 *

 * @return 1 if @p ptr is part of @p array, 0 otherwise

 */

#define IS_ARRAY_ELEMENT(array, ptr)                                                               \

	((ptr) && POINTER_TO_UINT(array) <= POINTER_TO_UINT(ptr) &&                          \

	 POINTER_TO_UINT(ptr) < POINTER_TO_UINT(&(array)[ARRAY_SIZE(array)]) &&                    \

	 (POINTER_TO_UINT(ptr) - POINTER_TO_UINT(array)) % sizeof((array)[0]) == 0)

/**

 * @brief Index of @p ptr within @p array

 *

 * With `CONFIG_ASSERT=y`, this macro will trigger a runtime assertion

 * when @p ptr does not fall into the range of @p array or when @p ptr

 * is not aligned to an array-element boundary of @p array.

 *

 * In C, passing a pointer as @p array causes a compile error.

 *

 * @param array the array in question

 * @param ptr pointer to an element of @p array

 *

 * @return the array index of @p ptr within @p array, on success

 */

#define ARRAY_INDEX(array, ptr)                                                                    \

	({                                                                                         \

		__ASSERT_NO_MSG(IS_ARRAY_ELEMENT(array, ptr));                                     \

		(__typeof__((array)[0]) *)(ptr) - (array);                                         \

	})

/**

 * @brief Check if a pointer @p ptr lies within @p array.

 *

 * In C but not C++, this causes a compile error if @p array is not an array

 * (e.g. if @p ptr and @p array are mixed up).

 *

 * @param ptr a pointer

 * @param array an array

 * @param ptr a pointer

 * @return 1 if @p ptr is part of @p array, 0 otherwise

 */

#define PART_OF_ARRAY(array, ptr)                                                                  \

	((ptr) && ((ptr) >= &array[0] && (ptr) < &array[ARRAY_SIZE(array)]))

	((ptr) && POINTER_TO_UINT(array) <= POINTER_TO_UINT(ptr) &&                                \

	 POINTER_TO_UINT(ptr) < POINTER_TO_UINT(&(array)[ARRAY_SIZE(array)]))

/**

 * @brief Array-index of @p ptr within @p array, rounded down

 *

 * This macro behaves much like @ref ARRAY_INDEX with the notable

 * difference that it accepts any @p ptr in the range of @p array rather than

 * exclusively a @p ptr aligned to an array-element boundary of @p array.

 *

 * With `CONFIG_ASSERT=y`, this macro will trigger a runtime assertion

 * when @p ptr does not fall into the range of @p array.

 *

 * In C, passing a pointer as @p array causes a compile error.

 *

 * @param array the array in question

 * @param ptr pointer to an element of @p array

 *

 * @return the array index of @p ptr within @p array, on success

 */

#define ARRAY_INDEX_FLOOR(array, ptr)                                                              \

	({                                                                                         \

		__ASSERT_NO_MSG(PART_OF_ARRAY(array, ptr));                                        \

		(POINTER_TO_UINT(ptr) - POINTER_TO_UINT(array)) / sizeof((array)[0]);              \

	})

/**

 * @brief Get a pointer to a structure containing the element