/**
* @file rtems/score/context.h
*
* This include file contains all information about each thread's context.
*/
/*
* COPYRIGHT (c) 1989-2006.
* 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.
*
* $Id$
*/
#ifndef _RTEMS_SCORE_CONTEXT_H
#define _RTEMS_SCORE_CONTEXT_H
/**
* @defgroup ScoreContext Context Handler
*
* This handler encapsulates functionality which abstracts thread context
* management in a portable manner.
*/
/**@{*/
#ifdef __cplusplus
extern "C" {
#endif
#include <rtems/score/cpu.h>
/**
* @brief Size of Floating Point Context Area
*
* This constant defines the number of bytes required
* to store a full floating point context.
*/
#define CONTEXT_FP_SIZE CPU_CONTEXT_FP_SIZE
/**
* @brief Is Context Switch Needed?
*
* This variable is set to TRUE when a reschedule operation
* has determined that the processor should be taken away from the
* currently executing thread and given to the heir thread.
*/
SCORE_EXTERN volatile boolean _Context_Switch_necessary;
/**
* @brief Initialize Context Area
* This routine initializes @a _the_context such that the stack
* pointer, interrupt level, and entry point are correct for the
* thread's initial state.
*
* @param[in] _the_context will be initialized
* @param[in] _stack is the lowest physical address of the thread's
* context
* @param[in] _size is the size in octets of the thread's context
* @param[in] _isr is the ISR enable level for this thread
* @param[in] _entry is this thread's entry point
* @param[in] _is_fp is set to TRUE if this thread has floating point
* enabled
*/
#define _Context_Initialize(_the_context, _stack, _size, _isr, _entry, _is_fp) \
_CPU_Context_Initialize( _the_context, _stack, _size, _isr, _entry, _is_fp )
/**
* This macro is invoked from _Thread_Handler to do whatever CPU
* specific magic is required that must be done in the context of
* the thread when it starts.
*
* If the CPU architecture does not require any magic, then this
* macro is empty.
*/
#if defined(_CPU_Context_Initialization_at_thread_begin)
#define _Context_Initialization_at_thread_begin() \
_CPU_Context_Initialization_at_thread_begin()
#else
#define _Context_Initialization_at_thread_begin()
#endif
/**
* @brief Perform Context Switch
*
* This routine saves the current context into the @a _executing
* context record and restores the context specified by @a _heir.
*
* @param[in] _executing is the currently executing thread's context
* @param[in] _heir is the context of the thread to be switched to
*/
#define _Context_Switch( _executing, _heir ) \
_CPU_Context_switch( _executing, _heir )
/**
* @brief Restart Currently Executing Thread
*
* This routine restarts the calling thread by restoring its initial
* stack pointer and returning to the thread's entry point.
*
* @param[in] _the_context is the context of the thread to restart
*/
#define _Context_Restart_self( _the_context ) \
_CPU_Context_Restart_self( _the_context )
/**
* @brief Return Starting Address of Floating Point Context
*
* This function returns the starting address of the floating
* point context save area. It is assumed that the are reserved
* for the floating point save area is large enough.
*
* @param[in] _base is lowest physical address of the floating point
* context save area.
* @param[in] _offset is the offset into the floating point area
*
* @return the initial FP context pointer
*/
#define _Context_Fp_start( _base, _offset ) \
_CPU_Context_Fp_start( (_base), (_offset) )
/**
* @brief Initialize Floating Point Context Area
*
* This routine initializes the floating point context save
* area to contain an initial known state.
*
* @param[in] _fp_area is the base address of the floating point
* context save area to initialize.
*/
#define _Context_Initialize_fp( _fp_area ) \
_CPU_Context_Initialize_fp( _fp_area )
/**
* @brief Restore Floating Point Context Area
*
* This routine restores the floating point context contained
* in the @a _fp area. It is assumed that the current
* floating point context has been saved by a previous invocation
* of @a _Context_Save_fp.
*
* @param[in] _fp points to the floating point context area to restore.
*/
#define _Context_Restore_fp( _fp ) \
_CPU_Context_restore_fp( _fp )
/**
* @brief Save Floating Point Context Area
*
* This routine saves the current floating point context
* in the @a _fp area.
*
* @param[in] _fp points to the floating point context area to restore.
*/
#define _Context_Save_fp( _fp ) \
_CPU_Context_save_fp( _fp )
#ifdef __cplusplus
}
#endif
/**@}*/
#endif
/* end of include file */
