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/*
* Copyright (c) 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 __SAT_COUNTER_HH__
#define __SAT_COUNTER_HH__
#include <string>
#include "predictor.hh"
#include "statistics.hh"
#include "sim_stats.hh"
struct stat_sdb_t;
//
//
// A simple saturating counter predictor
//
//
class SaturatingCounterPred : public GenericPredictor
{
private:
std::string pred_name;
std::string zero_name;
std::string one_name;
unsigned index_bits;
unsigned counter_bits;
unsigned zero_change;
unsigned one_change;
unsigned thresh;
unsigned init_value;
unsigned max_value; // maximum counter value
unsigned long max_index; // also the index mask value
unsigned *table;
// Statistics
Statistics::Scalar<> predicted_one; // Total predictions of one, preds_one
Statistics::Scalar<> predicted_zero; // Total predictions of zero, preds_zero
Statistics::Scalar<> correct_pred_one; // Total correct predictions of one, correct_one
Statistics::Scalar<> correct_pred_zero; // Total correct predictions of zero, correct_zero
Statistics::Scalar<> record_zero; //updates_zero
Statistics::Scalar<> record_one; //updates_one
Statistics::Formula preds_total;
Statistics::Formula pred_frac_zero;
Statistics::Formula pred_frac_one;
Statistics::Formula correct_total;
Statistics::Formula updates_total;
Statistics::Formula pred_rate;
Statistics::Formula frac_correct_zero;
Statistics::Formula frac_correct_one;
Statistics::Formula coverage_zero;
Statistics::Formula coverage_one;
private:
bool pred_one(unsigned &counter) { return counter > thresh; }
bool pred_zero(unsigned &counter) { return counter <= thresh; }
void update_one(unsigned &counter) {
if (one_change)
counter += one_change;
else
counter = 0;
// check for wrap
if (counter > max_value)
counter = max_value;
}
void update_zero(unsigned &counter) {
if (zero_change) {
// check for wrap
if (counter < zero_change)
counter = 0;
else
counter -= zero_change;
} else
counter = 0;
}
public:
SaturatingCounterPred(std::string p_name,
std::string z_name, std::string o_name,
unsigned _index_bits, unsigned _counter_bits = 2,
unsigned _zero_change = 1, unsigned _one_change = 1,
unsigned _thresh = 1, unsigned _init_value = 0);
void clear() {
for (int i = 0; i <= max_index; ++i)
table[i] = init_value;
}
// Record the ACTUAL result... and indicate whether the prediction
// corresponding to this event was correct
void record(unsigned long _index, unsigned _val, unsigned _predicted,
unsigned _pdata)
{
record(_index, _val, _predicted);
}
void record(unsigned long _index, unsigned _val, unsigned _predicted) {
unsigned long index = _index & max_index;
if (_val) {
update_one(table[index]);
++record_one;
if (_predicted)
++correct_pred_one;
} else {
update_zero(table[index]);
++record_zero;
if (!_predicted)
++correct_pred_zero;
}
}
unsigned value(unsigned long _index) {
unsigned long index = _index & max_index;
return table[index];
}
unsigned predict(unsigned long _index, unsigned &pdata) {
return predict(_index);
}
unsigned predict(unsigned long _index) {
unsigned long index = _index & max_index;
if (pred_one(table[index])) {
++predicted_one;
return 1;
}
++predicted_zero;
return 0;
}
// No internal state is changed here
unsigned peek(unsigned long _index) {
unsigned long index = _index & max_index;
if (pred_one(table[index]))
return 1;
return 0;
}
//=======================================================
void regStats();
void regFormulas();
};
#endif // __SAT_COUNTER_HH__
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