LXR linux/include/linux/kconfig.h

   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 following 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 __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/*
  39 * IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0
  40 * otherwise. For boolean options, this is equivalent to
  41 * IS_ENABLED(CONFIG_FOO).
  42 */
  43#define IS_BUILTIN(option) __is_defined(option)
  44
  45/*
  46 * IS_MODULE(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'm', 0
  47 * otherwise.
  48 */
  49#define IS_MODULE(option) __is_defined(option##_MODULE)
  50
  51/*
  52 * IS_REACHABLE(CONFIG_FOO) evaluates to 1 if the currently compiled
  53 * code can call a function defined in code compiled based on CONFIG_FOO.
  54 * This is similar to IS_ENABLED(), but returns false when invoked from
  55 * built-in code when CONFIG_FOO is set to 'm'.
  56 */
  57#define IS_REACHABLE(option) __or(IS_BUILTIN(option), \
  58                                __and(IS_MODULE(option), __is_defined(MODULE)))
  59
  60/*
  61 * IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm',
  62 * 0 otherwise.
  63 */
  64#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
  65
  66#endif /* __LINUX_KCONFIG_H */
  67