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b229baa3 AS |
1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | ||
3 | #ifndef _LINUX_ARGS_H | |
4 | #define _LINUX_ARGS_H | |
5 | ||
6 | /* | |
7 | * How do these macros work? | |
8 | * | |
9 | * In __COUNT_ARGS() _0 to _12 are just placeholders from the start | |
10 | * in order to make sure _n is positioned over the correct number | |
11 | * from 12 to 0 (depending on X, which is a variadic argument list). | |
12 | * They serve no purpose other than occupying a position. Since each | |
13 | * macro parameter must have a distinct identifier, those identifiers | |
14 | * are as good as any. | |
15 | * | |
16 | * In COUNT_ARGS() we use actual integers, so __COUNT_ARGS() returns | |
17 | * that as _n. | |
18 | */ | |
19 | ||
d51e783c KS |
20 | /* This counts to 15. Any more, it will return 16th argument. */ |
21 | #define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _n, X...) _n | |
22 | #define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) | |
b229baa3 AS |
23 | |
24 | /* Concatenate two parameters, but allow them to be expanded beforehand. */ | |
25 | #define __CONCAT(a, b) a ## b | |
26 | #define CONCATENATE(a, b) __CONCAT(a, b) | |
27 | ||
28 | #endif /* _LINUX_ARGS_H */ |