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/*
* Copyright (c) 1999-2008 Mark D. Hill and David A. Wood
* 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.
*/
#include "mem/ruby/filters/MultiBitSelBloomFilter.hh"
#include <limits>
#include "base/bitfield.hh"
#include "base/logging.hh"
#include "params/BloomFilterMultiBitSel.hh"
namespace BloomFilter {
MultiBitSel::MultiBitSel(const BloomFilterMultiBitSelParams* p)
: Base(p), numHashes(p->num_hashes),
parFilterSize(p->size / numHashes),
isParallel(p->is_parallel), skipBits(p->skip_bits)
{
if (p->size % numHashes) {
fatal("Can't divide filter (%d) in %d equal portions", p->size,
numHashes);
}
}
MultiBitSel::~MultiBitSel()
{
}
void
MultiBitSel::set(Addr addr)
{
for (int i = 0; i < numHashes; i++) {
int idx = hash(addr, i);
filter[idx] = 1;
}
}
int
MultiBitSel::getCount(Addr addr) const
{
int count = 0;
for (int i=0; i < numHashes; i++) {
count += filter[hash(addr, i)];
}
return count;
}
int
MultiBitSel::hash(Addr addr, int hash_number) const
{
uint64_t value = bits(addr, std::numeric_limits<Addr>::digits - 1,
offsetBits) >> skipBits;
const int max_bits = std::numeric_limits<Addr>::digits - offsetBits;
int result = 0;
int bit, i;
for (i = 0; i < sizeBits; i++) {
bit = (hash_number + numHashes * i) % max_bits;
if (value & (1 << bit)) {
result += 1 << i;
}
}
if (isParallel) {
return (result % parFilterSize) + hash_number * parFilterSize;
} else {
return result % filter.size();
}
}
} // namespace BloomFilter
BloomFilter::MultiBitSel*
BloomFilterMultiBitSelParams::create()
{
return new BloomFilter::MultiBitSel(this);
}
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