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        filter[hash(addr, i)]++;
62    }
63}
64
65int
66MultiBitSel::getCount(Addr addr) const
67{
68    int count = 0;
69    for (int i=0; i < numHashes; i++) {
70        count += filter[hash(addr, i)];
71    }
72    return count;
73}
74
75int
76MultiBitSel::hash(Addr addr, int hash_number) const
77{
78    uint64_t value = bits(addr, std::numeric_limits<Addr>::digits - 1,
79        offsetBits) >> skipBits;
80    const int max_bits = std::numeric_limits<Addr>::digits - offsetBits;
81    int result = 0;
82    int bit, i;
83
84    for (i = 0; i < sizeBits; i++) {
85        bit = (hash_number + numHashes * i) % max_bits;
86        if (value & (1 << bit)) {
87            result += 1 << i;
88        }
89    }
90
91    if (isParallel) {
92        return (result % parFilterSize) + hash_number * parFilterSize;
93    } else {
94        return result % filter.size();
95    }
96}
97
98} // namespace BloomFilter
99
100BloomFilter::MultiBitSel*
101BloomFilterMultiBitSelParams::create()
102{
103    return new BloomFilter::MultiBitSel(this);
104}
105
106