realtime.h

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/* -*- c++ -*- */
/*
 * Copyright 2006,2008 Free Software Foundation, Inc.
 * 
 * This file is part of GNU Radio
 * 
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 * 
 * GNU Radio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#ifndef INCLUDED_GRUEL_REALTIME_H
#define INCLUDED_GRUEL_REALTIME_H

#include <gruel/api.h>
#include <stdexcept>

/*!
 * \brief System independent way to ask for realtime scheduling
 *
 * \sa sys_pri.h
 */

namespace gruel {

  typedef enum {
    RT_OK = 0,
    RT_NOT_IMPLEMENTED,
    RT_NO_PRIVS,
    RT_OTHER_ERROR
  } rt_status_t;


  enum rt_sched_policy {
    RT_SCHED_RR   = 0,          // round robin
    RT_SCHED_FIFO = 1,          // first in first out
  };

  /*
   * Define the range for our virtual priorities (don't change these)
   *
   * Processes (or threads) with numerically higher priority values
   * are scheduled before processes with numerically lower priority
   * values.  Thus, the value returned by rt_priority_max() will be
   * greater than the value returned by rt_priority_min().
   */
  static inline int rt_priority_min() { return  0; }
  static inline int rt_priority_max() { return 15; }
  static inline int rt_priority_default() { return 1; }

  struct GRUEL_API rt_sched_param {
    int                 priority;
    rt_sched_policy     policy;

    rt_sched_param()
      : priority(rt_priority_default()), policy(RT_SCHED_RR){}

    rt_sched_param(int priority_, rt_sched_policy policy_ = RT_SCHED_RR)
    {
      if (priority_ < rt_priority_min() || priority_ > rt_priority_max())
        throw std::invalid_argument("rt_sched_param: priority out of range");

      priority = priority_;
      policy = policy_;
    }
  };

  /*!
   * \brief If possible, enable "realtime" scheduling.
   * \ingroup misc
   *
   * In general, this means that the code will be scheduled before any
   * non-realtime (normal) processes.  Note that if your code contains
   * an non-blocking infinite loop and you enable realtime scheduling,
   * it's possible to hang the system.
   */

  // NOTE: If you change this, you need to change the code in 
  // gnuradio-core/src/lib/runtime/gr_realtime.i, see note there.
  rt_status_t
  GRUEL_API enable_realtime_scheduling(rt_sched_param = rt_sched_param());

} // namespace gruel

#endif /* INCLUDED_GRUEL_REALTIME_H */