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 | |
20 | /* This counts to 12. Any more, it will return 13th argument. */ |
21 | #define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _n, X...) _n |
22 | #define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) |
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 */ |
29 | |