multi_bit_sel_bloom_filter.cc revision 14262:991410960fdb 
1/*
2 * Copyright (c) 2019 Inria
3 * Copyright (c) 1999-2008 Mark D. Hill and David A. Wood
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are
8 * met: redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer;
10 * redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution;
13 * neither the name of the copyright holders nor the names of its
14 * contributors may be used to endorse or promote products derived from
15 * this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * Authors: Daniel Carvalho
30 */
31
32#include "base/filters/multi_bit_sel_bloom_filter.hh"
33
34#include <limits>
35
36#include "base/bitfield.hh"
37#include "base/logging.hh"
38#include "params/BloomFilterMultiBitSel.hh"
39
40namespace BloomFilter {
41
42MultiBitSel::MultiBitSel(const BloomFilterMultiBitSelParams* p)
43    : Base(p), numHashes(p->num_hashes),
44      parFilterSize(p->size / numHashes),
45      isParallel(p->is_parallel), skipBits(p->skip_bits)
46{
47    if (p->size % numHashes) {
48        fatal("Can't divide filter (%d) in %d equal portions", p->size,
49              numHashes);
50    }
51}
52
53MultiBitSel::~MultiBitSel()
54{
55}
56
57void
58MultiBitSel::set(Addr addr)
59{
60    for (int i = 0; i < numHashes; i++) {
61        int idx = hash(addr, i);
62        filter[idx] = 1;
63    }
64}
65
66int
67MultiBitSel::getCount(Addr addr) const
68{
69    int count = 0;
70    for (int i=0; i < numHashes; i++) {
71        count += filter[hash(addr, i)];
72    }
73    return count;
74}
75
76int
77MultiBitSel::hash(Addr addr, int hash_number) const
78{
79    uint64_t value = bits(addr, std::numeric_limits<Addr>::digits - 1,
80        offsetBits) >> skipBits;
81    const int max_bits = std::numeric_limits<Addr>::digits - offsetBits;
82    int result = 0;
83    int bit, i;
84
85    for (i = 0; i < sizeBits; i++) {
86        bit = (hash_number + numHashes * i) % max_bits;
87        if (value & (1 << bit)) {
88            result += 1 << i;
89        }
90    }
91
92    if (isParallel) {
93        return (result % parFilterSize) + hash_number * parFilterSize;
94    } else {
95        return result % filter.size();
96    }
97}
98
99} // namespace BloomFilter
100
101BloomFilter::MultiBitSel*
102BloomFilterMultiBitSelParams::create()
103{
104    return new BloomFilter::MultiBitSel(this);
105}
106
107