Linux kernel mirror (for testing)
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linux
1#ifndef __LINUX_KCONFIG_H
2#define __LINUX_KCONFIG_H
3
4#include <generated/autoconf.h>
5
6#define __ARG_PLACEHOLDER_1 0,
7#define __take_second_arg(__ignored, val, ...) val
8
9/*
10 * The use of "&&" / "||" is limited in certain expressions.
11 * The followings enable to calculate "and" / "or" with macro expansion only.
12 */
13#define __and(x, y) ___and(x, y)
14#define ___and(x, y) ____and(__ARG_PLACEHOLDER_##x, y)
15#define ____and(arg1_or_junk, y) __take_second_arg(arg1_or_junk y, 0)
16
17#define __or(x, y) ___or(x, y)
18#define ___or(x, y) ____or(__ARG_PLACEHOLDER_##x, y)
19#define ____or(arg1_or_junk, y) __take_second_arg(arg1_or_junk 1, y)
20
21/*
22 * Helper macros to use CONFIG_ options in C/CPP expressions. Note that
23 * these only work with boolean and tristate options.
24 */
25
26/*
27 * Getting something that works in C and CPP for an arg that may or may
28 * not be defined is tricky. Here, if we have "#define CONFIG_BOOGER 1"
29 * we match on the placeholder define, insert the "0," for arg1 and generate
30 * the triplet (0, 1, 0). Then the last step cherry picks the 2nd arg (a one).
31 * When CONFIG_BOOGER is not defined, we generate a (... 1, 0) pair, and when
32 * the last step cherry picks the 2nd arg, we get a zero.
33 */
34#define config_enabled(cfg) ___is_defined(cfg)
35#define __is_defined(x) ___is_defined(x)
36#define ___is_defined(val) ____is_defined(__ARG_PLACEHOLDER_##val)
37#define ____is_defined(arg1_or_junk) __take_second_arg(arg1_or_junk 1, 0)
38
39/*
40 * IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0
41 * otherwise. For boolean options, this is equivalent to
42 * IS_ENABLED(CONFIG_FOO).
43 */
44#define IS_BUILTIN(option) config_enabled(option)
45
46/*
47 * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0
48 * otherwise.
49 */
50#define IS_MODULE(option) config_enabled(option##_MODULE)
51
52/*
53 * IS_REACHABLE(CONFIG_FOO) evaluates to 1 if the currently compiled
54 * code can call a function defined in code compiled based on CONFIG_FOO.
55 * This is similar to IS_ENABLED(), but returns false when invoked from
56 * built-in code when CONFIG_FOO is set to 'm'.
57 */
58#define IS_REACHABLE(option) __or(IS_BUILTIN(option), \
59 __and(IS_MODULE(option), __is_defined(MODULE)))
60
61/*
62 * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm',
63 * 0 otherwise.
64 */
65#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
66
67#endif /* __LINUX_KCONFIG_H */