1b229baa3SAndy Shevchenko /* SPDX-License-Identifier: GPL-2.0 */ 2b229baa3SAndy Shevchenko 3b229baa3SAndy Shevchenko #ifndef _LINUX_ARGS_H 4b229baa3SAndy Shevchenko #define _LINUX_ARGS_H 5b229baa3SAndy Shevchenko 6b229baa3SAndy Shevchenko /* 7b229baa3SAndy Shevchenko * How do these macros work? 8b229baa3SAndy Shevchenko * 9b229baa3SAndy Shevchenko * In __COUNT_ARGS() _0 to _12 are just placeholders from the start 10b229baa3SAndy Shevchenko * in order to make sure _n is positioned over the correct number 11b229baa3SAndy Shevchenko * from 12 to 0 (depending on X, which is a variadic argument list). 12b229baa3SAndy Shevchenko * They serve no purpose other than occupying a position. Since each 13b229baa3SAndy Shevchenko * macro parameter must have a distinct identifier, those identifiers 14b229baa3SAndy Shevchenko * are as good as any. 15b229baa3SAndy Shevchenko * 16b229baa3SAndy Shevchenko * In COUNT_ARGS() we use actual integers, so __COUNT_ARGS() returns 17b229baa3SAndy Shevchenko * that as _n. 18b229baa3SAndy Shevchenko */ 19b229baa3SAndy Shevchenko 20*d51e783cSKP Singh /* This counts to 15. Any more, it will return 16th argument. */ 21*d51e783cSKP Singh #define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _n, X...) _n 22*d51e783cSKP Singh #define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) 23b229baa3SAndy Shevchenko 24b229baa3SAndy Shevchenko /* Concatenate two parameters, but allow them to be expanded beforehand. */ 25b229baa3SAndy Shevchenko #define __CONCAT(a, b) a ## b 26b229baa3SAndy Shevchenko #define CONCATENATE(a, b) __CONCAT(a, b) 27b229baa3SAndy Shevchenko 28b229baa3SAndy Shevchenko #endif /* _LINUX_ARGS_H */ 29