Contiki-NG
atomic.h
1 /*
2  * Copyright (c) 2019, Toshiba Corporation
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditions and the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the copyright holder nor the names of its
15  * contributors may be used to endorse or promote products derived
16  * from this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
22  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
25  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
27  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
29  * OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 /*---------------------------------------------------------------------------*/
32 /**
33  * \addtogroup sys
34  * @{
35  *
36  * \defgroup atomic Atomic operations
37  * @{
38  *
39  * This library provides an API and generic implementation of atomic
40  * operations.
41  *
42  * The structure of this library is more or less the same as
43  * sys/mutex. By default, atomic operations are implemented by
44  * disabling interrupts temporarily. Platforms can provide better
45  * implementation using platform-specific features.
46  *
47  */
48 #ifndef ATOMIC_H_
49 #define ATOMIC_H_
50 
51 #include <contiki.h>
52 #include <stdint.h>
53 #include <stdbool.h>
54 
55 #ifdef ATOMIC_CONF_ARCH_HEADER_PATH
56 #include ATOMIC_CONF_ARCH_HEADER_PATH
57 #endif /* ATOMIC_CONF_ARCH_HEADER_PATH */
58 
59 /**
60  * \brief Atomic compare-and-swap (CAS) on a byte.
61  *
62  * This macro expands to atomic_generic_cas_uint8() or CPU-provided
63  * implementation. Platform-independent code should use this macro
64  * instead of atomic_generic_cas_uint8().
65  */
66 #ifndef atomic_cas_uint8
67 #define atomic_cas_uint8(t,o,n) atomic_generic_cas_uint8((t),(o),(n))
68 #endif /* atomic_cas_uint8 */
69 
70 /**
71  * \brief Atomic compare-and-swap (CAS) on a byte (generic impl.)
72  * \param target Pointer to the target byte to manipulate.
73  * \param old_val Value that is expected to be stored in the target.
74  * \param new_val Value that it stores to the target.
75  *
76  * If value of target is equal to old_val, store new_val to
77  * target. If the store operation succeeds, it returns true.
78  * Otherwise, it just returns false without storing.
79  */
80 bool atomic_generic_cas_uint8(uint8_t *target, uint8_t old_val, uint8_t new_val);
81 
82 #endif /* ATOMIC_H_ */
83 /**
84  * @}
85  * @}
86  */
bool atomic_generic_cas_uint8(uint8_t *target, uint8_t old_val, uint8_t new_val)
Atomic compare-and-swap (CAS) on a byte (generic impl.)
Definition: atomic.c:42