LXR linux/include/linux/kconfig.h

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