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