src/cpu/sched_list.hh

   1 /*
   2  * Copyright (c) 2002-2005 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Steve Raasch
  29  */
  30
  31 #ifndef SCHED_LIST_HH
  32 #define SCHED_LIST_HH
  33
  34 #include <list>
  35
  36 #include "base/intmath.hh"
  37 #include "base/misc.hh"
  38
  39 //  Any types you use this class for must be covered here...
  40 namespace {
  41     void ClearEntry(int &i) { i = 0; };
  42     void ClearEntry(unsigned &i) { i = 0; };
  43     void ClearEntry(double &i) { i = 0; };
  44     template <class T> void ClearEntry(std::list<T> &l) { l.clear(); };
  45 };
  46
  47
  48 //
  49 //  this is a special list type that allows the user to insert elements at a
  50 //  specified positive offset from the "current" element, but only allow them
  51 //  be extracted from the "current" element
  52 //
  53
  54
  55 template <class T>
  56 class SchedList
  57 {
  58     T *data_array;
  59     unsigned position;
  60     unsigned size;
  61     unsigned mask;
  62
  63   public:
  64     SchedList(unsigned size);
  65     SchedList(void);
  66
  67     void init(unsigned size);
  68
  69     T &operator[](unsigned offset);
  70
  71     void advance(void);
  72
  73     void clear(void);
  74 };
  75
  76
  77
  78 //
  79 //  Constructor
  80 //
  81 template<class T>
  82 SchedList<T>::SchedList(unsigned _size)
  83 {
  84     size = _size;
  85
  86     //  size must be a power of two
  87     if (!isPowerOf2(size)) {
  88         panic("SchedList: size must be a power of two");
  89     }
  90
  91     if (size < 2) {
  92         panic("SchedList: you don't want a list that small");
  93     }
  94
  95     //  calculate the bit mask for the modulo operation
  96     mask = size - 1;
  97
  98     data_array = new T[size];
  99
 100     if (!data_array) {
 101         panic("SchedList: could not allocate memory");
 102     }
 103
 104     clear();
 105 }
 106
 107 template<class T>
 108 SchedList<T>::SchedList(void)
 109 {
 110     data_array = 0;
 111     size = 0;
 112 }
 113
 114
 115 template<class T> void
 116 SchedList<T>::init(unsigned _size)
 117 {
 118     size = _size;
 119
 120     if (!data_array) {
 121         //  size must be a power of two
 122         if (size & (size-1)) {
 123             panic("SchedList: size must be a power of two");
 124         }
 125
 126         if (size < 2) {
 127             panic("SchedList: you don't want a list that small");
 128         }
 129
 130         //  calculate the bit mask for the modulo operation
 131         mask = size - 1;
 132
 133         data_array = new T[size];
 134
 135         if (!data_array) {
 136             panic("SchedList: could not allocate memory");
 137         }
 138
 139         clear();
 140     }
 141 }
 142
 143
 144 template<class T> void
 145 SchedList<T>::advance(void)
 146 {
 147     ClearEntry(data_array[position]);
 148
 149     //    position = (++position % size);
 150     position = ++position & mask;
 151 }
 152
 153
 154 template<class T> void
 155 SchedList<T>::clear(void)
 156 {
 157     for (unsigned i=0; i<size; ++i) {
 158         ClearEntry(data_array[i]);
 159     }
 160
 161     position = 0;
 162 }
 163
 164
 165 template<class T>  T&
 166 SchedList<T>::operator[](unsigned offset)
 167 {
 168     if (offset >= size) {
 169         panic("SchedList: can't access element beyond current pointer");
 170     }
 171
 172     //    unsigned p = (position + offset) % size;
 173     unsigned p = (position + offset) & mask;
 174
 175     return data_array[p];
 176 }
 177
 178
 179
 180 #endif