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modules.h
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/*
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* Copyright (C) 2014 Freie Universität Berlin
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* 2017 HAW-Hamburg
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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#ifndef MODULES_H
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#define MODULES_H
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#ifdef __cplusplus
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extern
"C"
{
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#endif
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#define IS_ACTIVE(macro) __is_active(macro)
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#define IS_USED(module) IS_ACTIVE(module)
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/* Here a prefix "__PREFIX_WHEN_" is added to the macro. So if it was a 1 we
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* have "__PREFIX_WHEN_1", and if it was not defined we have "__PREFIX_WHEN_".
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*/
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#define __is_active(val) ___is_active(__PREFIX_WHEN_##val)
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/* With this placeholder we turn the original value into two arguments when the
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* original value was defined as 1 (note the comma).
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*/
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#define __PREFIX_WHEN_1 0,
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/* Here we add two extra arguments, that way the next macro can accept varargs.
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*
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* If the original macro was defined as 1, this will have three arguments
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* (__take_second_arg(0, 1, 0, 0)), otherwise it will have two
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* (__take_second_arg(__PREFIX_WHEN_ 1, 0, 0)). The third zero is there just to
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* be compliant with C99, which states that when a function-like macro ends
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* with ellipsis (...) it should be called with at least one argument for the
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* variable list.
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*/
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#define ___is_active(arg1_or_junk) __take_second_arg(arg1_or_junk 1, 0, 0)
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/* Finally, we just always take the second argument, which will be either 1
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* (when three arguments are passed, i.e. macro was defined as 1) or 0 (when
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* only two arguments are passed).
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*/
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#define __take_second_arg(__ignored, val, ...) val
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#ifdef __cplusplus
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}
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#endif
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#endif
/* MODULES_H */
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