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/**
* @file
*
* @brief Priority Handler API
*/
/*
* COPYRIGHT (c) 1989-2011.
* On-Line Applications Research Corporation (OAR).
*
* Copyright (c) 2016 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.org/license/LICENSE.
*/
#ifndef _RTEMS_SCORE_PRIORITY_H
#define _RTEMS_SCORE_PRIORITY_H
#include <rtems/score/chain.h>
#include <rtems/score/cpu.h>
#include <rtems/score/rbtree.h>
struct Scheduler_Control;
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup ScorePriority Priority Handler
*
* @ingroup Score
*
* This handler encapsulates functionality which is used to manage thread
* priorities. The actual priority of a thread is an aggregation of priority
* nodes. The thread priority aggregation for the home scheduler instance of a
* thread consists of at least one priority node, which is normally the real
* priority of the thread. The locking protocols (e.g. priority ceiling and
* priority inheritance), rate-monotonic period objects and the POSIX sporadic
* server add, change and remove priority nodes.
*
* @{
*/
/**
* @brief A plain thread priority value.
*
* Lower values represent higher priorities. So, a priority value of zero
* represents the highest priority thread. This value is reserved for internal
* threads and the priority ceiling protocol.
*/
typedef uint64_t Priority_Control;
/**
* @brief The highest (most important) thread priority value.
*/
#define PRIORITY_MINIMUM 0
/**
* @brief The priority value of pseudo-ISR threads.
*
* Examples are the MPCI and timer server threads.
*/
#define PRIORITY_PSEUDO_ISR PRIORITY_MINIMUM
/**
* @brief The default lowest (least important) thread priority value.
*
* This value is CPU port dependent.
*/
#if defined (CPU_PRIORITY_MAXIMUM)
#define PRIORITY_DEFAULT_MAXIMUM CPU_PRIORITY_MAXIMUM
#else
#define PRIORITY_DEFAULT_MAXIMUM 255
#endif
/**
* @brief The priority node to build up a priority aggregation.
*/
typedef struct {
/**
* @brief Node component for a chain or red-black tree.
*/
union {
Chain_Node Chain;
RBTree_Node RBTree;
} Node;
/**
* @brief The priority value of this node.
*/
Priority_Control priority;
} Priority_Node;
/**
* @brief The priority action type.
*/
typedef enum {
PRIORITY_ACTION_ADD,
PRIORITY_ACTION_CHANGE,
PRIORITY_ACTION_REMOVE,
PRIORITY_ACTION_INVALID
} Priority_Action_type;
typedef struct Priority_Aggregation Priority_Aggregation;
/**
* @brief The priority aggregation.
*
* This structure serves two purposes. Firstly, it provides a place to
* register priority nodes and reflects the overall priority of its
* contributors. Secondly, it provides an action block to signal addition,
* change and removal of a priority node.
*/
struct Priority_Aggregation {
/**
* @brief This priority node reflects the overall priority of the aggregation.
*
* The overall priority of the aggregation is the minimum priority of the
* priority nodes in the contributors tree.
*
* This priority node may be used to add this aggregation to another
* aggregation to build up a recursive priority scheme.
*
* In case priority nodes of the contributors tree are added, changed or
* removed the priority of this node may change. To signal such changes to a
* priority aggregation the action block may be used.
*/
Priority_Node Node;
/**
* @brief A red-black tree to contain priority nodes contributing to the
* overall priority of this priority aggregation.
*/
RBTree_Control Contributors;
#if defined(RTEMS_SMP)
/**
* @brief The scheduler instance of this priority aggregation.
*/
const struct Scheduler_Control *scheduler;
#endif
/**
* @brief A priority action block to manage priority node additions, changes
* and removals.
*/
struct {
#if defined(RTEMS_SMP)
/**
* @brief The next priority aggregation in the action list.
*/
Priority_Aggregation *next;
#endif
/**
* @brief The priority node of the action.
*/
Priority_Node *node;
/**
* @brief The type of the action.
*/
Priority_Action_type type;
} Action;
};
/**
* @brief A list of priority actions.
*
* Actions are only added to the list. The action lists reside on the stack
* and have a short life-time. They are moved, processed or destroyed as a
* whole.
*/
typedef struct {
/**
* @brief The first action of a priority action list.
*/
Priority_Aggregation *actions;
} Priority_Actions;
#ifdef __cplusplus
}
#endif
/**@}*/
#endif
/* end of include file */
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