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