1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __LINUX_KCONFIG_H
3#define __LINUX_KCONFIG_H
4
5#include <generated/autoconf.h>
6
7#ifdef CONFIG_CPU_BIG_ENDIAN
8#define __BIG_ENDIAN 4321
9#else
10#define __LITTLE_ENDIAN 1234
11#endif
12
13#define __ARG_PLACEHOLDER_1 0,
14#define __take_second_arg(__ignored, val, ...) val
15
16/*
17 * The use of "&&" / "||" is limited in certain expressions.
18 * The following enable to calculate "and" / "or" with macro expansion only.
19 */
20#define __and(x, y) ___and(x, y)
21#define ___and(x, y) ____and(__ARG_PLACEHOLDER_##x, y)
22#define ____and(arg1_or_junk, y) __take_second_arg(arg1_or_junk y, 0)
23
24#define __or(x, y) ___or(x, y)
25#define ___or(x, y) ____or(__ARG_PLACEHOLDER_##x, y)
26#define ____or(arg1_or_junk, y) __take_second_arg(arg1_or_junk 1, y)
27
28/*
29 * Helper macros to use CONFIG_ options in C/CPP expressions. Note that
30 * these only work with boolean and tristate options.
31 */
32
33/*
34 * Getting something that works in C and CPP for an arg that may or may
35 * not be defined is tricky. Here, if we have "#define CONFIG_BOOGER 1"
36 * we match on the placeholder define, insert the "0," for arg1 and generate
37 * the triplet (0, 1, 0). Then the last step cherry picks the 2nd arg (a one).
38 * When CONFIG_BOOGER is not defined, we generate a (... 1, 0) pair, and when
39 * the last step cherry picks the 2nd arg, we get a zero.
40 */
41#define __is_defined(x) ___is_defined(x)
42#define ___is_defined(val) ____is_defined(__ARG_PLACEHOLDER_##val)
43#define ____is_defined(arg1_or_junk) __take_second_arg(arg1_or_junk 1, 0)
44
45/*
46 * IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0
47 * otherwise. For boolean options, this is equivalent to
48 * IS_ENABLED(CONFIG_FOO).
49 */
50#define IS_BUILTIN(option) __is_defined(option)
51
52/*
53 * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0
54 * otherwise. CONFIG_FOO=m results in "#define CONFIG_FOO_MODULE 1" in
55 * autoconf.h.
56 */
57#define IS_MODULE(option) __is_defined(option##_MODULE)
58
59/*
60 * IS_REACHABLE(CONFIG_FOO) evaluates to 1 if the currently compiled
61 * code can call a function defined in code compiled based on CONFIG_FOO.
62 * This is similar to IS_ENABLED(), but returns false when invoked from
63 * built-in code when CONFIG_FOO is set to 'm'.
64 */
65#define IS_REACHABLE(option) __or(IS_BUILTIN(option), \
66 __and(IS_MODULE(option), __is_defined(MODULE)))
67
68/*
69 * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm',
70 * 0 otherwise. Note that CONFIG_FOO=y results in "#define CONFIG_FOO 1" in
71 * autoconf.h, while CONFIG_FOO=m results in "#define CONFIG_FOO_MODULE 1".
72 */
73#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
74
75#endif /* __LINUX_KCONFIG_H */
76