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