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atomic-cortex.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 arm
34 *
35 * Arm Cortex-M implementation of atomic operations using the LDREX,
36 * STREX and DMB instructions.
37 *
38 * @{
39 */
40#ifndef ATOMIC_CORTEX_H_
41#define ATOMIC_CORTEX_H_
42#include <contiki.h>
43
44#ifdef CMSIS_CONF_HEADER_PATH
45#include CMSIS_CONF_HEADER_PATH
46#endif
47
48#include <stdint.h>
49#include <stdbool.h>
50
51#define atomic_cas_uint8(t,o,n) atomic_cortex_cas_uint8((t),(o),(n))
52
53static inline bool
54atomic_cortex_cas_uint8(uint8_t *target, uint8_t old_val, uint8_t new_val)
55{
56 int status = 1;
57
58 if(__LDREXB(target) == old_val) {
59 status = __STREXB(new_val, target);
60 }
61
62 __DMB();
63
64 return status == 0 ? true : false;
65}
66
67#endif /* ATOMIC_CORTEX_H_ */
68/** @} */