/**  *  @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: priority.h,v 1.21 2006/01/16 15:13:58 joel Exp $ */#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 __cplusplusextern "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 */