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/**
* @brief Constants and Structures Related with Thread Dispatch
*/
/*
* COPYRIGHT (c) 1989-2009.
* On-Line Applications Research Corporation (OAR).
*
* 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_THREADDISPATCH_H
#define _RTEMS_SCORE_THREADDISPATCH_H
#include <rtems/score/cpu.h>
#include <rtems/score/smplock.h>
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#if defined(RTEMS_SMP) || \
defined(RTEMS_HEAVY_STACK_DEBUG) || \
defined(RTEMS_HEAVY_MALLOC_DEBUG)
#define __THREAD_DO_NOT_INLINE_DISABLE_DISPATCH__
#endif
#if defined(RTEMS_SMP) || \
(CPU_INLINE_ENABLE_DISPATCH == FALSE) || \
(__RTEMS_DO_NOT_INLINE_THREAD_ENABLE_DISPATCH__ == 1)
#define __THREAD_DO_NOT_INLINE_ENABLE_DISPATCH__
#endif
/**
* @addtogroup ScoreThread
*
* @{
*/
/**
* The following declares the dispatch critical section nesting
* counter which is used to prevent context switches at inopportune
* moments.
*/
SCORE_EXTERN volatile uint32_t _Thread_Dispatch_disable_level;
/**
* @brief Indicates if the executing thread is inside a thread dispatch
* critical section.
*
* @retval true Thread dispatching is enabled.
* @retval false The executing thread is inside a thread dispatch critical
* section and dispatching is not allowed.
*/
RTEMS_INLINE_ROUTINE bool _Thread_Dispatch_is_enabled(void)
{
return _Thread_Dispatch_disable_level == 0;
}
#if defined(RTEMS_SMP)
typedef struct {
SMP_lock_Control lock;
int owner_cpu;
int nest_level;
} Thread_Dispatch_disable_level_lock_control;
/**
* The following declares the smp spinlock to be used to control
* the dispatch critical section accesses across cpus.
*/
SCORE_EXTERN Thread_Dispatch_disable_level_lock_control
_Thread_Dispatch_disable_level_lock;
/**
* @brief Initializes the thread dispatching subsystem.
*
* This routine initializes the thread dispatching subsystem.
*/
void _Thread_Dispatch_initialization(void);
/**
* @brief Returns value of the the thread dispatch level.
*
* This routine returns value of the the thread dispatch level.
*/
uint32_t _Thread_Dispatch_get_disable_level(void);
/**
* @brief Sets thread dispatch level to the value passed in.
*
* This routine sets thread dispatch level to the
* value passed in.
*/
uint32_t _Thread_Dispatch_set_disable_level(uint32_t value);
/**
* @brief Increments the thread dispatch level.
*
* This rountine increments the thread dispatch level
*/
uint32_t _Thread_Dispatch_increment_disable_level(void);
/**
* @brief Decrements the thread dispatch level.
*
* This routine decrements the thread dispatch level.
*/
uint32_t _Thread_Dispatch_decrement_disable_level(void);
#else /* RTEMS_SMP */
/**
* @brief Get thread dispatch disable level.
*
* This routine returns value of the the thread dispatch level.
*/
RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_get_disable_level(void)
{
return _Thread_Dispatch_disable_level;
}
/**
* @brief Set thread dispatch disable level.
*
* This routine sets thread dispatch level to the
* value passed in.
*/
RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_set_disable_level(uint32_t value)
{
_Thread_Dispatch_disable_level = value;
return value;
}
/**
* @brief Increase thread dispatch disable level.
*
* This rountine increments the thread dispatch level
*/
RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_increment_disable_level(void)
{
uint32_t level = _Thread_Dispatch_disable_level;
++level;
_Thread_Dispatch_disable_level = level;
return level;
}
/**
* @brief Decrease thread dispatch disable level.
*
* This routine decrements the thread dispatch level.
*/
RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_decrement_disable_level(void)
{
uint32_t level = _Thread_Dispatch_disable_level;
--level;
_Thread_Dispatch_disable_level = level;
return level;
}
/**
* @brief Thread dispatch initialization.
*
* This routine initializes the thread dispatching subsystem.
*/
RTEMS_INLINE_ROUTINE void _Thread_Dispatch_initialization( void )
{
_Thread_Dispatch_set_disable_level( 1 );
}
#endif /* RTEMS_SMP */
/**
* @brief Dispatch thread.
*
* This routine is responsible for transferring control of the
* processor from the executing thread to the heir thread. Once the
* heir is running an attempt is made to dispatch any ASRs.
* As part of this process, it is responsible for the following actions:
* + saving the context of the executing thread
* + restoring the context of the heir thread
* + dispatching any signals for the resulting executing thread
* ALTERNATE ENTRY POINTS:
* void _Thread_Enable_dispatch();
*
* - INTERRUPT LATENCY:
* + dispatch thread
* + no dispatch thread
*/
void _Thread_Dispatch( void );
/**
* This routine prevents dispatching.
*/
#if defined ( __THREAD_DO_NOT_INLINE_DISABLE_DISPATCH__ )
void _Thread_Disable_dispatch( void );
#else
RTEMS_INLINE_ROUTINE void _Thread_Disable_dispatch( void )
{
_Thread_Dispatch_increment_disable_level();
RTEMS_COMPILER_MEMORY_BARRIER();
}
#endif
/**
* This routine allows dispatching to occur again. If this is
* the outer most dispatching critical section, then a dispatching
* operation will be performed and, if necessary, control of the
* processor will be transferred to the heir thread.
*/
#if defined ( __THREAD_DO_NOT_INLINE_ENABLE_DISPATCH__ )
void _Thread_Enable_dispatch( void );
#else
/* inlining of enable dispatching must be true */
RTEMS_INLINE_ROUTINE void _Thread_Enable_dispatch( void )
{
RTEMS_COMPILER_MEMORY_BARRIER();
if ( _Thread_Dispatch_decrement_disable_level() == 0 )
_Thread_Dispatch();
}
#endif
/**
* This routine allows dispatching to occur again. However,
* no dispatching operation is performed even if this is the outer
* most dispatching critical section.
*/
RTEMS_INLINE_ROUTINE void _Thread_Unnest_dispatch( void )
{
RTEMS_COMPILER_MEMORY_BARRIER();
_Thread_Dispatch_decrement_disable_level();
}
/** @} */
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* _RTEMS_SCORE_THREADDISPATCH_H */
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