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/*
* Copyright (c) 2002-2003 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
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