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/**
* @file
*
* @brief POSIX Priority Support
*
* This include file defines the interface to the POSIX priority
* implementation.
*/
/*
* COPYRIGHT (c) 1989-2011.
* 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.org/license/LICENSE.
*/
#ifndef _RTEMS_POSIX_PRIORITYIMPL_H
#define _RTEMS_POSIX_PRIORITYIMPL_H
#include <rtems/score/scheduler.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup POSIX_PRIORITY POSIX Priority Support
*
* @ingroup POSIXAPI
*
* @brief Interface to the POSIX Priority Implementation
*
*/
/**@{**/
/**
* 1003.1b-1993,2.2.2.80 definition of priority, p. 19
*
* "Numerically higher values represent higher priorities."
*
* Thus, RTEMS Core has priorities run in the opposite sense of the POSIX API.
*
* There are only 254 posix priority levels since a task at priority level
* 255 would never run because of the RTEMS idle task. This is necessary
* because GNAT maps the lowest Ada task priority to the lowest thread
* priority. The lowest priority Ada task should get to run, so there is
* a fundamental conflict with having 255 priorities.
*
* But since RTEMS can be configured with fewer than 256 priorities,
* we use the internal constant.
*/
#define POSIX_SCHEDULER_MAXIMUM_PRIORITY (PRIORITY_MAXIMUM - 1)
/**
* This is the numerically least important POSIX priority.
*/
#define POSIX_SCHEDULER_MINIMUM_PRIORITY (1)
/**
* @brief Gets the maximum POSIX API priority for this scheduler instance.
*
* Such a priority is valid. A scheduler instance may support priority values
* that are not representable as an integer.
*
* @return The maximum POSIX API priority for this scheduler instance.
*/
int _POSIX_Priority_Get_maximum( const Scheduler_Control *scheduler );
/**
* @brief Check if POSIX priority is valid.
*
* 1003.1b-1993,2.2.2.80 definition of priority, p. 19
*
* "Numerically higher values represent higher priorities."
*
* Thus, RTEMS Core has priorities run in the opposite sense of the POSIX API.
*
* @param[in] priority is the priority to test
*
* @retval TRUE The priority is valid.
* @retval FALSE The priority is invalid.
*/
bool _POSIX_Priority_Is_valid(
int priority
);
/**
* @brief Convert POSIX priority to SuperCore priority.
*
* This method converts a POSIX API priority into onto the corresponding
* SuperCore value.
*
* @param[in] priority is the POSIX API priority.
*
* @return This method returns the corresponding SuperCore priority.
*/
RTEMS_INLINE_ROUTINE Priority_Control _POSIX_Priority_To_core(
int priority
)
{
return (Priority_Control) (POSIX_SCHEDULER_MAXIMUM_PRIORITY - priority + 1);
}
/**
* @brief Convert SuperCore priority To POSIX priority.
*
* This method converts a SuperCore priority into onto the corresponding
* POSIX API value.
*
* @param[in] priority is the POSIX API priority.
*
* @return This method returns the corresponding POSIX priority.
*/
RTEMS_INLINE_ROUTINE int _POSIX_Priority_From_core(
Priority_Control priority
)
{
return (POSIX_SCHEDULER_MAXIMUM_PRIORITY - priority + 1);
}
/** @} */
#ifdef __cplusplus
}
#endif
#endif
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