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 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)
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