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cortex-m3: Add atomic_cas implementation

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This commit is contained in:
Joakim Gebart 2015-04-28 23:08:31 +02:00
parent 46b9358e84
commit b7db351400
2 changed files with 26 additions and 12 deletions
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30
cpu/cortex-m3_common/atomic_arch.c
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@ -10,23 +10,37 @@
* @ingroup cpu_cortexm3_common
* @{
*
* @file atomic_arch.c
* @file
* @brief Implementation of the kernels atomic interface
*
* @author Stefan Pfeiffer <stefan.pfeiffer@fu-berlin.de>
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
* @author Joakim Gebart <joakim.gebart@eistec.se>
*
* @}
*/
#include "arch/atomic_arch.h"
#include <stdint.h>
#include "atomic.h"
#include "irq.h"
#include "cpu.h"
unsigned int atomic_arch_set_return(unsigned int *to_set, unsigned int value)
int atomic_cas(atomic_int_t *var, int old, int now)
{
disableIRQ();
unsigned int old = *to_set;
*to_set = value;
enableIRQ();
return old;
int tmp;
int status;
/* Load exclusive */
tmp = __LDREXW((volatile uint32_t *)(&ATOMIC_VALUE(*var)));
if (tmp != old) {
/* Clear memory exclusivity */
__CLREX();
return 0;
}
/* Try to write the new value */
status = __STREXW(now, (volatile uint32_t *)(&ATOMIC_VALUE(*var)));
return (status == 0);
}

8
cpu/cortex-m3_common/include/cpu.h
View File

@ -23,13 +23,13 @@
* @author Joakim Gebart <joakim.gebart@eistec.se>
*/
#ifndef __CORTEXM_COMMON_H
#define __CORTEXM_COMMON_H
#ifndef CORTEXM_COMMON_H_
#define CORTEXM_COMMON_H_
/**
* @brief Cortex-M3 has architecture specific atomic operations in atomic_arch.c.
*/
#define ARCH_HAS_ATOMIC_INT 1
#define ARCH_HAS_ATOMIC_COMPARE_AND_SWAP 1
#include "cpu-conf.h"
@ -55,5 +55,5 @@ void cpu_init(void);
}
#endif
#endif /* __CORTEXM_COMMON_H */
#endif /* CORTEXM_COMMON_H_ */
/** @} */