kconfig.h 2.6 KB

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  1. /* SPDX-License-Identifier: GPL-2.0 */
  2. #ifndef __LINUX_KCONFIG_H
  3. #define __LINUX_KCONFIG_H
  4. #include <generated/autoconf.h>
  5. #ifdef CONFIG_CPU_BIG_ENDIAN
  6. #define __BIG_ENDIAN 4321
  7. #else
  8. #define __LITTLE_ENDIAN 1234
  9. #endif
  10. #define __ARG_PLACEHOLDER_1 0,
  11. #define __take_second_arg(__ignored, val, ...) val
  12. /*
  13. * The use of "&&" / "||" is limited in certain expressions.
  14. * The following enable to calculate "and" / "or" with macro expansion only.
  15. */
  16. #define __and(x, y) ___and(x, y)
  17. #define ___and(x, y) ____and(__ARG_PLACEHOLDER_##x, y)
  18. #define ____and(arg1_or_junk, y) __take_second_arg(arg1_or_junk y, 0)
  19. #define __or(x, y) ___or(x, y)
  20. #define ___or(x, y) ____or(__ARG_PLACEHOLDER_##x, y)
  21. #define ____or(arg1_or_junk, y) __take_second_arg(arg1_or_junk 1, y)
  22. /*
  23. * Helper macros to use CONFIG_ options in C/CPP expressions. Note that
  24. * these only work with boolean and tristate options.
  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 __is_defined(x) ___is_defined(x)
  35. #define ___is_defined(val) ____is_defined(__ARG_PLACEHOLDER_##val)
  36. #define ____is_defined(arg1_or_junk) __take_second_arg(arg1_or_junk 1, 0)
  37. /*
  38. * IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0
  39. * otherwise. For boolean options, this is equivalent to
  40. * IS_ENABLED(CONFIG_FOO).
  41. */
  42. #define IS_BUILTIN(option) __is_defined(option)
  43. /*
  44. * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0
  45. * otherwise. CONFIG_FOO=m results in "#define CONFIG_FOO_MODULE 1" in
  46. * autoconf.h.
  47. */
  48. #define IS_MODULE(option) __is_defined(option##_MODULE)
  49. /*
  50. * IS_REACHABLE(CONFIG_FOO) evaluates to 1 if the currently compiled
  51. * code can call a function defined in code compiled based on CONFIG_FOO.
  52. * This is similar to IS_ENABLED(), but returns false when invoked from
  53. * built-in code when CONFIG_FOO is set to 'm'.
  54. */
  55. #define IS_REACHABLE(option) __or(IS_BUILTIN(option), \
  56. __and(IS_MODULE(option), __is_defined(MODULE)))
  57. /*
  58. * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm',
  59. * 0 otherwise. Note that CONFIG_FOO=y results in "#define CONFIG_FOO 1" in
  60. * autoconf.h, while CONFIG_FOO=m results in "#define CONFIG_FOO_MODULE 1".
  61. */
  62. #define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
  63. #endif /* __LINUX_KCONFIG_H */