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/**
* @file
*
* @ingroup ScoreSMPLockI386
*
* @brief i386 SMP Lock Implementation
*/
/*
* COPYRIGHT (c) 1989-2011.
* On-Line Applications Research Corporation (OAR).
*
* Copyright (c) 2013 embedded brains GmbH
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#ifndef _RTEMS_SCORE_I386_SMPLOCK_H
#define _RTEMS_SCORE_I386_SMPLOCK_H
#include <rtems/score/cpu.h>
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/**
* @defgroup ScoreSMPLockI386 i386 SMP Locks
*
* @ingroup ScoreSMPLock
*
* The implementation is Test and Swap.
*
* @{
*/
typedef struct {
uint32_t locked;
} CPU_SMP_lock_Control;
#define CPU_SMP_LOCK_INITIALIZER { 0 }
static inline void _CPU_SMP_lock_Initialize( CPU_SMP_lock_Control *lock )
{
lock->locked = 0;
}
static inline uint32_t _I386_Atomic_swap(
volatile uint32_t *address,
uint32_t value
)
{
uint32_t previous;
asm volatile(
"lock; xchgl %0, %1"
: "+m" (*address), "=a" (previous)
: "1" (value)
: "cc"
);
return previous;
}
static inline void _CPU_SMP_lock_Acquire( CPU_SMP_lock_Control *lock )
{
do {
while ( lock->locked ) {
RTEMS_COMPILER_MEMORY_BARRIER();
}
} while ( _I386_Atomic_swap( &lock->locked, 1 ) );
}
static inline void _CPU_SMP_lock_Release( CPU_SMP_lock_Control *lock )
{
RTEMS_COMPILER_MEMORY_BARRIER();
lock->locked = 0;
}
#define _CPU_SMP_lock_ISR_disable_and_acquire( lock, isr_cookie ) \
do { \
_CPU_ISR_Disable( isr_cookie ); \
_CPU_SMP_lock_Acquire( lock ); \
} while (0)
#define _CPU_SMP_lock_Release_and_ISR_enable( lock, isr_cookie ) \
do { \
_CPU_SMP_lock_Release( lock ); \
_CPU_ISR_Enable( isr_cookie ); \
} while (0)
/**@}*/
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* _RTEMS_SCORE_I386_SMPLOCK_H */
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