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/**
* @file rtems/score/priority.h
*
* This include file contains all thread priority manipulation routines.
* This Handler provides mechanisms which can be used to
* initialize and manipulate thread priorities.
*/
/*
* 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_PRIORITY_H
#define _RTEMS_SCORE_PRIORITY_H
/**
* @defgroup ScorePriority Priority Handler
*
* This handler encapsulates functionality which is used to manage
* thread priorities. At the SuperCore level 256 priority levels
* are supported with lower numbers representing logically more important
* threads. The priority level 0 is reserved for internal RTEMS use.
* Typically it is assigned to threads which defer internal RTEMS
* actions from an interrupt to thread level to improve interrupt response.
* Priority level 255 is assigned to the IDLE thread and really should not
* be used by application threads. The default IDLE thread implementation
* is an infinite "branch to self" loop which never yields to other threads
* at the same priority.
*/
/**@{*/
#ifdef __cplusplus
extern "C" {
#endif
/**
* The following type defines the control block used to manage
* thread priorities.
*
* @note Priority 0 is reserved for internal threads only.
*/
typedef uint32_t Priority_Control;
/** This defines the highest (most important) thread priority. */
#define PRIORITY_MINIMUM 0
/** This defines the lowest (least important) thread priority. */
#define PRIORITY_MAXIMUM 255
/**
* The following record defines the information associated with
* each thread to manage its interaction with the priority bit maps.
*/
typedef struct {
/** This is the address of minor bit map slot. */
Priority_Bit_map_control *minor;
/** This is the priority bit map ready mask. */
Priority_Bit_map_control ready_major;
/** This is the priority bit map ready mask. */
Priority_Bit_map_control ready_minor;
/** This is the priority bit map block mask. */
Priority_Bit_map_control block_major;
/** This is the priority bit map block mask. */
Priority_Bit_map_control block_minor;
} Priority_Information;
/**
* Each sixteen bit entry in this array is associated with one of
* the sixteen entries in the Priority Bit map.
*/
SCORE_EXTERN volatile Priority_Bit_map_control _Priority_Major_bit_map;
/** Each bit in the Priority Bitmap indicates whether or not there are
* threads ready at a particular priority. The mapping of
* individual priority levels to particular bits is processor
* dependent as is the value of each bit used to indicate that
* threads are ready at that priority.
*/
SCORE_EXTERN Priority_Bit_map_control
_Priority_Bit_map[16] CPU_STRUCTURE_ALIGNMENT;
/*
* The definition of the Priority_Bit_map_control type is CPU dependent.
*
*/
#if ( CPU_USE_GENERIC_BITFIELD_CODE == FALSE )
/**
* This method returns the priority bit mask for the specified major
* or minor bit number.
*
* @param[in] _bit_number is the bit number for which we need a mask
*
* @return the priority bit mask
*
* @note This may simply be a pass through to a CPU dependent implementation.
*/
#define _Priority_Mask( _bit_number ) \
_CPU_Priority_Mask( _bit_number )
#endif
#if ( CPU_USE_GENERIC_BITFIELD_CODE == FALSE )
/**
* This method returns the bit index position for the specified priority.
*
* @param[in] _priority is the priority for which we need the index.
*
* @return This method returns the array index into the priority bit map.
*
* @note This may simply be a pass through to a CPU dependent implementation.
*/
#define _Priority_Bits_index( _priority ) \
_CPU_Priority_bits_index( _priority )
#endif
#ifndef __RTEMS_APPLICATION__
#include <rtems/score/priority.inl>
#endif
#ifdef __cplusplus
}
#endif
/**@}*/
#endif
/* end of include file */
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