diff options
Diffstat (limited to 'lab02/container_of.h')
| -rw-r--r-- | lab02/container_of.h | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/lab02/container_of.h b/lab02/container_of.h index 87fb6d4..bffe7b7 100644 --- a/lab02/container_of.h +++ b/lab02/container_of.h @@ -1,22 +1,31 @@ /* SPDX-License-Identifier: GPL-2.0 */ +/** + * @file container_of.h + * @brief Provides type-aware container and member offset macros. + */ #ifndef _CONTAINER_OF_H #define _CONTAINER_OF_H #include <stddef.h> +/** @brief Checks whether two expressions have compatible types. */ #define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) +/** @brief Computes a member offset using the compiler builtin. */ #undef offsetof #define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER) +/** @brief Obtains the type of a member of a structure type. */ #define typeof_member(T, m) typeof(((T*)0)->m) /** - * container_of - cast a member of a structure out to the containing structure - * @ptr: the pointer to the member. - * @type: the type of the container struct this is embedded in. - * @member: the name of the member within the struct. + * @brief Converts a pointer to a structure member to its containing object. + * @param ptr A pointer to the member. + * @param type The type of the containing structure. + * @param member The member name within `type`. * + * The macro performs a compile-time type compatibility check before applying + * the member offset. */ #define container_of(ptr, type, member) ({ \ _Static_assert(__same_type(*(ptr), typeof_member(type, member)) || \ @@ -25,6 +34,12 @@ (type *)((void *)(ptr) - offsetof(type, member)); }) +/** + * @brief Converts a member pointer while preserving its const qualification. + * @param ptr A pointer to the member. + * @param type The type of the containing structure. + * @param member The member name within `type`. + */ #define container_of_const(ptr, type, member) \ _Generic(ptr, \ const typeof(*(ptr)) *: ((const type *)container_of(ptr, type, member)),\ |