linux/include/linux/args.h at multikernel-arm · multikernel/linux · GitHub

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/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _LINUX_ARGS_H

#define _LINUX_ARGS_H

* How do these macros work?

* In __COUNT_ARGS() _0 to _15 are just placeholders from the start

* in order to make sure _n is positioned over the correct number

* from 15 to 0 (depending on X, which is a variadic argument list).

* They serve no purpose other than occupying a position. Since each

* macro parameter must have a distinct identifier, those identifiers

* are as good as any.

* In COUNT_ARGS() we use actual integers, so __COUNT_ARGS() returns

* that as _n.

/* This counts to 15. Any more, it will return 16th argument. */

#define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _n, X...) _n

#define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)

/* Concatenate two parameters, but allow them to be expanded beforehand. */

#define __CONCAT(a, b) a ## b

#define CONCATENATE(a, b) __CONCAT(a, b)

#endif /* _LINUX_ARGS_H */

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