Contiki-NG
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 
53 static inline bool
54 atomic_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 /** @} */
__STATIC_INLINE void __DMB(void)
Data Memory Barrier.
Definition: cmsis_gcc.h:438