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
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