with isPowerOf2() from intmath.hh. base/sched_list.hh: Use isPowerOf2() from intmath.hh. --HG-- extra : convert_revision : 7b2409531d8ed194aa7e1cfcd1ecb8460c797a16
178 lines
4.2 KiB
C++
178 lines
4.2 KiB
C++
/*
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* Copyright (c) 2002-2005 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef SCHED_LIST_HH
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#define SCHED_LIST_HH
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#include <list>
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#include "base/intmath.hh"
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#include "base/misc.hh"
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// Any types you use this class for must be covered here...
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namespace {
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void ClearEntry(int &i) { i = 0; };
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void ClearEntry(unsigned &i) { i = 0; };
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void ClearEntry(double &i) { i = 0; };
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template <class T> void ClearEntry(std::list<T> &l) { l.clear(); };
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};
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//
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// this is a special list type that allows the user to insert elements at a
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// specified positive offset from the "current" element, but only allow them
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// be extracted from the "current" element
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//
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template <class T>
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class SchedList
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{
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T *data_array;
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unsigned position;
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unsigned size;
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unsigned mask;
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public:
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SchedList(unsigned size);
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SchedList(void);
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void init(unsigned size);
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T &operator[](unsigned offset);
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void advance(void);
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void clear(void);
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};
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//
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// Constructor
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//
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template<class T>
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SchedList<T>::SchedList(unsigned _size)
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{
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size = _size;
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// size must be a power of two
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if (!isPowerOf2(size)) {
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panic("SchedList: size must be a power of two");
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}
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if (size < 2) {
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panic("SchedList: you don't want a list that small");
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}
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// calculate the bit mask for the modulo operation
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mask = size - 1;
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data_array = new T[size];
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if (!data_array) {
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panic("SchedList: could not allocate memory");
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}
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clear();
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}
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template<class T>
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SchedList<T>::SchedList(void)
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{
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data_array = 0;
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size = 0;
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}
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template<class T> void
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SchedList<T>::init(unsigned _size)
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{
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size = _size;
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if (!data_array) {
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// size must be a power of two
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if (size & (size-1)) {
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panic("SchedList: size must be a power of two");
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}
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if (size < 2) {
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panic("SchedList: you don't want a list that small");
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}
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// calculate the bit mask for the modulo operation
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mask = size - 1;
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data_array = new T[size];
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if (!data_array) {
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panic("SchedList: could not allocate memory");
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}
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clear();
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}
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}
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template<class T> void
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SchedList<T>::advance(void)
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{
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ClearEntry(data_array[position]);
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// position = (++position % size);
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position = ++position & mask;
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}
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template<class T> void
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SchedList<T>::clear(void)
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{
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for (unsigned i=0; i<size; ++i) {
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ClearEntry(data_array[i]);
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}
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position = 0;
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}
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template<class T> T&
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SchedList<T>::operator[](unsigned offset)
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{
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if (offset >= size) {
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panic("SchedList: can't access element beyond current pointer");
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}
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// unsigned p = (position + offset) % size;
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unsigned p = (position + offset) & mask;
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return data_array[p];
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}
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#endif
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