/*
 * Copyright (c) 2011-2014, Wind River Systems, Inc.
 * Copyright (c) 2020, Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @file
 * @brief Misc utilities
 *
 * Repetitive or obscure helper macros needed by sys/util.h.
 */

#ifndef ZEPHYR_INCLUDE_SYS_UTIL_INTERNAL_H_
#define ZEPHYR_INCLUDE_SYS_UTIL_INTERNAL_H_

/* IS_ENABLED() helpers */

/* This is called from IS_ENABLED(), and sticks 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 1, 0)

/* 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 /* ZEPHYR_INCLUDE_SYS_UTIL_INTERNAL_H_ */