/* * Copyright (c) 2003 The Regents of The University of Michigan * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer; * 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; * neither the name of the copyright holders 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 OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef SCHED_LIST_HH #define SCHED_LIST_HH #include <list> #include "base/misc.hh" // Any types you use this class for must be covered here... namespace { void ClearEntry(int &i) { i = 0; }; void ClearEntry(unsigned &i) { i = 0; }; void ClearEntry(double &i) { i = 0; }; template <class T> void ClearEntry(std::list<T> &l) { l.clear(); }; }; // // this is a special list type that allows the user to insert elements at a // specified positive offset from the "current" element, but only allow them // be extracted from the "current" element // template <class T> class SchedList { T *data_array; unsigned position; unsigned size; unsigned mask; public: SchedList(unsigned size); SchedList(void); void init(unsigned size); T &operator[](unsigned offset); void advance(void); void clear(void); }; // // Constructor // template<class T> SchedList<T>::SchedList(unsigned _size) { size = _size; // size must be a power of two if (size & (size-1)) { panic("SchedList: size must be a power of two"); } if (size < 2) { panic("SchedList: you don't want a list that small"); } // calculate the bit mask for the modulo operation mask = size - 1; data_array = new T[size]; if (!data_array) { panic("SchedList: could not allocate memory"); } clear(); } template<class T> SchedList<T>::SchedList(void) { data_array = 0; size = 0; } template<class T> void SchedList<T>::init(unsigned _size) { size = _size; if (!data_array) { // size must be a power of two if (size & (size-1)) { panic("SchedList: size must be a power of two"); } if (size < 2) { panic("SchedList: you don't want a list that small"); } // calculate the bit mask for the modulo operation mask = size - 1; data_array = new T[size]; if (!data_array) { panic("SchedList: could not allocate memory"); } clear(); } } template<class T> void SchedList<T>::advance(void) { ClearEntry(data_array[position]); // position = (++position % size); position = ++position & mask; } template<class T> void SchedList<T>::clear(void) { for (unsigned i=0; i<size; ++i) { ClearEntry(data_array[i]); } position = 0; } template<class T> T& SchedList<T>::operator[](unsigned offset) { if (offset >= size) { panic("SchedList: can't access element beyond current pointer"); } // unsigned p = (position + offset) % size; unsigned p = (position + offset) & mask; return data_array[p]; } #endif