nuttx/include/stdbool.h

/****************************************************************************
 * include/stdbool.h
 *
 *   Copyright (C) 2009, 2011 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * 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.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
 * COPYRIGHT OWNER 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 __INCLUDE_STDBOOL_H
#define __INCLUDE_STDBOOL_H

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

/* If CONFIG_ARCH_STDBOOL_H is set, then the architecture will provide its
 * own stdbool.h file.  In this case, this header file will simply re-direct
 * to the architecture-specfic stdbool.h header file.
 */

#ifdef CONFIG_ARCH_STDBOOL_H
#  include <arch/stdbool.h>

/* NuttX will insist that the sizeof(bool) is 8-bits.  The sizeof of _Bool
 * used by any specific compiler is implementation specific: It can vary from
 * compiler-to-compiler and even vary between different versions of the same
 * compiler.  Compilers seems to be converging to sizeof(_Bool) == 1. If that
 * is true for your compiler, you should define CONFIG_C99_BOOL8 in your
 * NuttX configuration for better standards compatibility.
 *
 * CONFIG_C99_BOOL8 - Means (1) your C++ compiler has sizeof(_Bool) == 8,
 * (2) your C compiler supports the C99 _Bool intrinsic type, and (3) that
 * the C99 _Bool type also has size 1.
 */

#else

/* nuttx/compiler.h may also define or undefine CONFIG_C99_BOOL8 */

#  include <nuttx/compiler.h>
#  include <stdint.h>

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* bool, true, and false must be provided as macros so that they can be
 * redefined by the application if necessary.
 *
 * NOTE: Under C99 'bool' is required to be defined to be the intrinsic type
 * _Bool.  However, in this NuttX context, we need backward compatibility
 * to pre-C99 standards where _Bool is not an intrinsic type.  Hence, we
 * use _Bool8 as the underlying type (unless CONFIG_C99_BOOL8 is defined)
 */

#ifndef __cplusplus
#ifdef CONFIG_C99_BOOL8
#  define bool _Bool
#else
#  define bool _Bool8
#endif

#define true  (bool)1
#define false (bool)0

#define __bool_true_false_are_defined 1
#endif /* __cplusplus */

/****************************************************************************
 * Public Types
 ****************************************************************************/

/* A byte is the smallest address memory element (at least in architectures
 * that do not support bit banding).  The requirement is only that type _Bool
 * be large enough to hold the values 0 and 1.  We select uint8_t to minimize
 * the RAM footprint of the executable.
 *
 * NOTE: We can't actually define the type _Bool here.  Under C99 _Bool is
 * an intrinsic type and cannot be the target of a typedef.  However, in this
 * NuttX context, we also need backward compatibility to pre-C99 standards
 * where _Bool is not an intrinsic type.  We work around this by using _Bool8
 * as the underlying type.
 */

#ifndef CONFIG_C99_BOOL8
typedef uint8_t _Bool8;
#endif

#endif /* CONFIG_ARCH_STDBOOL_H */
#endif /* __INCLUDE_STDBOOL_H */