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/*
* Copyright (c) 2005-2006 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.
*
* Authors: Kevin Lim
*/
#ifndef __CPU_PRED_SAT_COUNTER_HH__
#define __CPU_PRED_SAT_COUNTER_HH__
#include "base/logging.hh"
#include "base/types.hh"
/**
* Private counter class for the internal saturating counters.
* Implements an n bit saturating counter and provides methods to
* increment, decrement, and read it.
* @todo Consider making this something that more closely mimics a
* built in class so you can use ++ or --.
*/
class SatCounter
{
public:
/**
* Constructor for the counter.
*/
SatCounter()
: initialVal(0), counter(0)
{ }
/**
* Constructor for the counter.
* @param bits How many bits the counter will have.
*/
SatCounter(unsigned bits)
: initialVal(0), maxVal((1 << bits) - 1), counter(0)
{ }
/**
* Constructor for the counter.
* @param bits How many bits the counter will have.
* @param initial_val Starting value for each counter.
*/
SatCounter(unsigned bits, uint8_t initial_val)
: initialVal(initial_val), maxVal((1 << bits) - 1),
counter(initial_val)
{
// Check to make sure initial value doesn't exceed the max
// counter value.
if (initial_val > maxVal) {
fatal("BP: Initial counter value exceeds max size.");
}
}
/**
* Sets the number of bits.
*/
void setBits(unsigned bits) { maxVal = (1 << bits) - 1; }
void reset() { counter = initialVal; }
/**
* Increments the counter's current value.
*/
void increment()
{
if (counter < maxVal) {
++counter;
}
}
/**
* Decrements the counter's current value.
*/
void decrement()
{
if (counter > 0) {
--counter;
}
}
/**
* Read the counter's value.
*/
uint8_t read() const
{ return counter; }
private:
uint8_t initialVal;
uint8_t maxVal;
uint8_t counter;
};
#endif // __CPU_PRED_SAT_COUNTER_HH__
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