| /* SPDX-License-Identifier: Apache-2.0 */ |
| /* |
| * Copyright (c) 2017 Intel Corporation |
| * |
| */ |
| #ifndef __CONFIG_H_ |
| #define __CONFIG_H_ |
| |
| /** |
| * @brief Check for macro definition in compiler-visible expressions |
| * |
| * This trick was pioneered in Linux as the config_enabled() macro. |
| * The madness has the effect of taking a macro value that may be |
| * defined to "1" (e.g. CONFIG_MYFEATURE), or may not be defined at |
| * all and turning it into a literal expression that can be used at |
| * "runtime". That is, it works similarly to |
| * "defined(CONFIG_MYFEATURE)" does except that it is an expansion |
| * that can exist in a standard expression and be seen by the compiler |
| * and optimizer. Thus much ifdef usage can be replaced with cleaner |
| * expressions like: |
| * |
| * if (IS_ENABLED(CONFIG_MYFEATURE)) |
| * myfeature_enable(); |
| * |
| * INTERNAL |
| * First pass just to expand any existing macros, we need the macro |
| * value to be e.g. a literal "1" at expansion time in the next macro, |
| * not "(1)", etc... Standard recursive expansion does not work. |
| */ |
| #define IS_ENABLED(config_macro) Z_IS_ENABLED1(config_macro) |
| |
| /* Now stick on a "_XXXX" prefix, it will now be "_XXXX1" if config_macro |
| * is "1", or just "_XXXX" if it's undefined. |
| * ENABLED: Z_IS_ENABLED2(_XXXX1) |
| * DISABLED Z_IS_ENABLED2(_XXXX) |
| */ |
| #define Z_IS_ENABLED1(config_macro) Z_IS_ENABLED2(_XXXX##config_macro) |
| |
| /* Here's the core trick, we map "_XXXX1" to "_YYYY," (i.e. a string |
| * with a trailing comma), so it has the effect of making this a |
| * two-argument tuple to the preprocessor only in the case where the |
| * value is defined to "1" |
| * ENABLED: _YYYY, <--- note comma! |
| * DISABLED: _XXXX |
| */ |
| #define _XXXX1 _YYYY, |
| |
| /* Then we append an extra argument to fool the gcc preprocessor into |
| * accepting it as a varargs macro. |
| * arg1 arg2 arg3 |
| * ENABLED: Z_IS_ENABLED3(_YYYY, 1, 0) |
| * DISABLED Z_IS_ENABLED3(_XXXX 1, 0) |
| */ |
| #define Z_IS_ENABLED2(one_or_two_args) \ |
| Z_IS_ENABLED3(one_or_two_args true, false) |
| |
| /* And our second argument is thus now cooked to be 1 in the case |
| * where the value is defined to 1, and 0 if not: |
| */ |
| #define Z_IS_ENABLED3(ignore_this, val, ...) val |
| |
| #endif // __CONFIG_H_ |
