1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux 1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _LINUX_STDDEF_H 2 #ifndef _LINUX_STDDEF_H
3 #define _LINUX_STDDEF_H 3 #define _LINUX_STDDEF_H
4 4
5 5
6 6
7 #ifndef __always_inline 7 #ifndef __always_inline
8 #define __always_inline __inline__ 8 #define __always_inline __inline__
9 #endif 9 #endif
10 10
11 /** 11 /**
12 * __struct_group() - Create a mirrored named 12 * __struct_group() - Create a mirrored named and anonyomous struct
13 * 13 *
14 * @TAG: The tag name for the named sub-struct 14 * @TAG: The tag name for the named sub-struct (usually empty)
15 * @NAME: The identifier name of the mirrored 15 * @NAME: The identifier name of the mirrored sub-struct
16 * @ATTRS: Any struct attributes (usually empt 16 * @ATTRS: Any struct attributes (usually empty)
17 * @MEMBERS: The member declarations for the m 17 * @MEMBERS: The member declarations for the mirrored structs
18 * 18 *
19 * Used to create an anonymous union of two st 19 * Used to create an anonymous union of two structs with identical layout
20 * and size: one anonymous and one named. The 20 * and size: one anonymous and one named. The former's members can be used
21 * normally without sub-struct naming, and the 21 * normally without sub-struct naming, and the latter can be used to
22 * reason about the start, end, and size of th 22 * reason about the start, end, and size of the group of struct members.
23 * The named struct can also be explicitly tag 23 * The named struct can also be explicitly tagged for layer reuse, as well
24 * as both having struct attributes appended. 24 * as both having struct attributes appended.
25 */ 25 */
26 #define __struct_group(TAG, NAME, ATTRS, MEMBE 26 #define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \
27 union { \ 27 union { \
28 struct { MEMBERS } ATTRS; \ 28 struct { MEMBERS } ATTRS; \
29 struct TAG { MEMBERS } ATTRS N 29 struct TAG { MEMBERS } ATTRS NAME; \
30 } 30 }
31 31
32 /** 32 /**
33 * __DECLARE_FLEX_ARRAY() - Declare a flexible 33 * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union
34 * 34 *
35 * @TYPE: The type of each flexible array elem 35 * @TYPE: The type of each flexible array element
36 * @NAME: The name of the flexible array membe 36 * @NAME: The name of the flexible array member
37 * 37 *
38 * In order to have a flexible array member in 38 * In order to have a flexible array member in a union or alone in a
39 * struct, it needs to be wrapped in an anonym 39 * struct, it needs to be wrapped in an anonymous struct with at least 1
40 * named member, but that member can be empty. 40 * named member, but that member can be empty.
41 */ 41 */
42 #define __DECLARE_FLEX_ARRAY(TYPE, NAME) 42 #define __DECLARE_FLEX_ARRAY(TYPE, NAME) \
43 struct { \ 43 struct { \
44 struct { } __empty_ ## NAME; \ 44 struct { } __empty_ ## NAME; \
45 TYPE NAME[]; \ 45 TYPE NAME[]; \
46 } 46 }
47 #endif 47 #endif
48 48
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