src/cpu/o3/sat_counter.hh

   1 /*
   2  * Copyright (c) 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
  29 #ifndef __CPU_O3_CPU_SAT_COUNTER_HH__
  30 #define __CPU_O3_CPU_SAT_COUNTER_HH__
  31
  32 #include "sim/host.hh"
  33
  34 /**
  35  * Private counter class for the internal saturating counters.
  36  * Implements an n bit saturating counter and provides methods to
  37  * increment, decrement, and read it.
  38  * @todo Consider making this something that more closely mimics a
  39  * built in class so you can use ++ or --.
  40  */
  41 class SatCounter
  42 {
  43   public:
  44     /**
  45      * Constructor for the counter.
  46      */
  47     SatCounter();
  48
  49     /**
  50      * Constructor for the counter.
  51      * @param bits How many bits the counter will have.
  52      */
  53     SatCounter(unsigned bits);
  54
  55     /**
  56      * Constructor for the counter.
  57      * @param bits How many bits the counter will have.
  58      * @param initial_val Starting value for each counter.
  59      */
  60     SatCounter(unsigned bits, unsigned initial_val);
  61
  62     /**
  63      * Sets the number of bits.
  64      */
  65     void setBits(unsigned bits);
  66
  67     /**
  68      * Increments the counter's current value.
  69      */
  70     void increment();
  71
  72     /**
  73      * Decrements the counter's current value.
  74      */
  75     void decrement();
  76
  77     /**
  78      * Read the counter's value.
  79      */
  80     const uint8_t read() const
  81     {
  82         return counter;
  83     }
  84
  85   private:
  86     uint8_t maxVal;
  87     uint8_t counter;
  88 };
  89
  90 #endif // __CPU_O3_CPU_SAT_COUNTER_HH__