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/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2020 The FreeBSD Foundation
*
* This software was developed by Björn Zeeb under sponsorship from
* the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _LINUXKPI_LINUX_KCONFIG_H_
#define _LINUXKPI_LINUX_KCONFIG_H_
/*
* Checking if an option is defined would be easy if we could do CPP inside CPP.
* The defined case whether -Dxxx or -Dxxx=1 are easy to deal with. In either
* case the defined value is "1". A more general -Dxxx=<c> case will require
* more effort to deal with all possible "true" values. Hope we do not have
* to do this as well.
* The real problem is the undefined case. To avoid this problem we do the
* concat/varargs trick: "yyy" ## xxx can make two arguments if xxx is "1"
* by having a #define for yyy_1 which is "ignore,".
* Otherwise we will just get "yyy".
* Need to be careful about variable substitutions in macros though.
* This way we make a (true, false) problem a (don't care, true, false) or a
* (don't care true, false). Then we can use a variadic macro to only select
* the always well known and defined argument #2. And that seems to be
* exactly what we need. Use 1 for true and 0 for false to also allow
* #if IS_*() checks pre-compiler checks which do not like #if true.
*/
#define ___XAB_1 dontcare,
#define ___IS_XAB(_ignore, _x, ...) (_x)
#define __IS_XAB(_x) ___IS_XAB(_x 1, 0)
#define _IS_XAB(_x) __IS_XAB(__CONCAT(___XAB_, _x))
/* This is if CONFIG_ccc=y. */
#define IS_BUILTIN(_x) _IS_XAB(_x)
/* This is if CONFIG_ccc=m. */
#define IS_MODULE(_x) _IS_XAB(_x ## _MODULE)
/* This is if CONFIG_ccc is compiled in(=y) or a module(=m). */
#define IS_ENABLED(_x) (IS_BUILTIN(_x) || IS_MODULE(_x))
/*
* This is weird case. If the CONFIG_ccc is builtin (=y) this returns true;
* or if the CONFIG_ccc is a module (=m) and the caller is built as a module
* (-DMODULE defined) this returns true, but if the callers is not a module
* (-DMODULE not defined, which means caller is BUILTIN) then it returns
* false. In other words, a module can reach the kernel, a module can reach
* a module, but the kernel cannot reach a module, and code never compiled
* cannot be reached either.
* XXX -- I'd hope the module-to-module case would be handled by a proper
* module dependency definition (MODULE_DEPEND() in FreeBSD).
*/
#define IS_REACHABLE(_x) (IS_BUILTIN(_x) || \
(IS_MODULE(_x) && IS_BUILTIN(MODULE)))
#endif /* _LINUXKPI_LINUX_KCONFIG_H_ */
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