/************************************************************************
* sched/sched_rrgetinterval.c
*
* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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************************************************************************/
/************************************************************************
* Included Files
************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <sched.h>
#include <errno.h>
#include <nuttx/arch.h>
#include "os_internal.h"
#include "clock_internal.h"
/************************************************************************
* Definitions
************************************************************************/
/************************************************************************
* Private Type Declarations
************************************************************************/
/************************************************************************
* Global Variables
************************************************************************/
/************************************************************************
* Private Variables
************************************************************************/
/************************************************************************
* Private Function Prototypes
************************************************************************/
/************************************************************************
* Private Functions
************************************************************************/
/************************************************************************
* Public Functions
************************************************************************/
/************************************************************************
* Name: sched_rr_get_interval
*
* Description:
* sched_rr_get_interval() writes the timeslice interval for task
* identified by 'pid' into the timespec structure pointed to by
* 'interval.' If pid is zero, the timeslice for the calling process
* is written into 'interval. The identified process should be running
* under the SCHED_RRscheduling policy.'
*
* Inputs:
* pid - the task ID of the task. If pid is zero, the priority of the
* calling task is returned.
* interval - a structure used to return the time slice
*
* Return Value:
* On success, sched_rr_get_interval() returns OK (0). On error,
* ERROR (-1) is returned, and errno is set to:
*
* EFAULT -- Cannot copy to interval
* EINVAL Invalid pid.
* ENOSYS The system call is not yet implemented.
* ESRCH The process whose ID is pid could not be found.
*
* Assumptions:
*
************************************************************************/
int sched_rr_get_interval(pid_t pid, struct timespec *interval)
{
#if CONFIG_RR_INTERVAL > 0
FAR struct tcb_s *rrtcb;
/* If pid is zero, the timeslice for the calling process is written
* into 'interval.'
*/
if (!pid)
{
rrtcb = (FAR struct tcb_s*)g_readytorun.head;
}
/* Return a special error code on invalid PID */
else if (pid < 0)
{
set_errno(EINVAL);
return ERROR;
}
/* Otherwise, lookup the TCB associated with this pid */
else
{
rrtcb = sched_gettcb(pid);
if (!rrtcb)
{
set_errno(ESRCH);
return ERROR;
}
}
if (!interval)
{
set_errno(EFAULT);
return ERROR;
}
/* Convert the timeslice value from ticks to timespec */
interval->tv_sec = CONFIG_RR_INTERVAL / MSEC_PER_SEC;
interval->tv_nsec = (CONFIG_RR_INTERVAL % MSEC_PER_SEC) * NSEC_PER_MSEC;
return OK;
#else
set_errno(ENOSYS);
return ERROR;
#endif
}
