src/base/filters/bulk_bloom_filter.cc

   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/bulk_bloom_filter.hh"
  33
  34 #include <vector>
  35
  36 #include <limits>
  37
  38 #include "base/bitfield.hh"
  39 #include "params/BloomFilterBulk.hh"
  40
  41 namespace BloomFilter {
  42
  43 Bulk::Bulk(const BloomFilterBulkParams* p)
  44     : Base(p), sectorBits(sizeBits - 1)
  45 {
  46 }
  47
  48 Bulk::~Bulk()
  49 {
  50 }
  51
  52 void
  53 Bulk::set(Addr addr)
  54 {
  55     // c0 contains the cache index bits
  56     int c0 = bits(addr, offsetBits + sectorBits - 1, offsetBits);
  57     // c1 contains the lower sectorBits permuted bits
  58     //Address permuted_bits = permute(addr);
  59     int c1 = bits(addr, (offsetBits + 2 * sectorBits) - 1,
  60         offsetBits + sectorBits);
  61     //assert(c0 < (filter_size/2));
  62     //assert(c0 + (filter_size/2) < filter_size);
  63     //assert(c1 < (filter_size/2));
  64     // set v0 bit
  65     filter[c0 + (filter.size()/2)] = 1;
  66     // set v1 bit
  67     filter[c1] = 1;
  68 }
  69
  70 bool
  71 Bulk::isSet(Addr addr) const
  72 {
  73     // c0 contains the cache index bits
  74     const int filter_size = filter.size();
  75     int c0 = bits(addr, offsetBits + sectorBits - 1, offsetBits);
  76     // c1 contains the lower 10 permuted bits
  77     //Address permuted_bits = permute(addr);
  78     int c1 = bits(addr, (offsetBits + 2 * sectorBits) - 1,
  79         offsetBits + sectorBits);
  80     //assert(c0 < (filter_size/2));
  81     //assert(c0 + (filter_size/2) < filter_size);
  82     //assert(c1 < (filter_size/2));
  83     // set v0 bit
  84     std::vector<int> temp_filter(filter.size(), 0);
  85     temp_filter[c0 + (filter_size/2)] = 1;
  86     // set v1 bit
  87     temp_filter[c1] = 1;
  88
  89     // perform filter intersection. If any c part is 0, no possibility
  90     // of address being in signature.  get first c intersection part
  91     bool zero = false;
  92     for (int i = 0; i < filter_size/2; ++i){
  93         // get intersection of signatures
  94         temp_filter[i] = temp_filter[i] && filter[i];
  95         zero = zero || temp_filter[i];
  96     }
  97     zero = !zero;
  98     if (zero) {
  99         // one section is zero, no possiblility of address in signature
 100         // reset bits we just set
 101         temp_filter[c0 + (filter_size / 2)] = 0;
 102         temp_filter[c1] = 0;
 103         return false;
 104     }
 105
 106     // check second section
 107     zero = false;
 108     for (int i = filter_size / 2; i < filter_size; ++i) {
 109         // get intersection of signatures
 110         temp_filter[i] =  temp_filter[i] && filter[i];
 111         zero = zero || temp_filter[i];
 112     }
 113     zero = !zero;
 114     if (zero) {
 115         // one section is zero, no possiblility of address in signature
 116         temp_filter[c0 + (filter_size / 2)] = 0;
 117         temp_filter[c1] = 0;
 118         return false;
 119     }
 120     // one section has at least one bit set
 121     temp_filter[c0 + (filter_size / 2)] = 0;
 122     temp_filter[c1] = 0;
 123     return true;
 124 }
 125
 126 int
 127 Bulk::getCount(Addr addr) const
 128 {
 129     // TODO as in the multi-hashed filters
 130     return 0;
 131 }
 132
 133 Addr
 134 Bulk::hash(Addr addr) const
 135 {
 136     // permutes the original address bits according to Table 5
 137     Addr part1  = bits(addr, offsetBits + 6, offsetBits),
 138          part2  = bits(addr, offsetBits + 9),
 139          part3  = bits(addr, offsetBits + 11),
 140          part4  = bits(addr, offsetBits + 17),
 141          part5  = bits(addr, offsetBits + 8, offsetBits + 7),
 142          part6  = bits(addr, offsetBits + 10),
 143          part7  = bits(addr, offsetBits + 12),
 144          part8  = bits(addr, offsetBits + 13),
 145          part9  = bits(addr, offsetBits + 16, offsetBits + 15),
 146          part10 = bits(addr, offsetBits + 20, offsetBits + 18),
 147          part11 = bits(addr, offsetBits + 14);
 148
 149     Addr result =
 150         (part1 << 14) | (part2 << 13) | (part3 << 12) | (part4 << 11) |
 151         (part5 << 9)  | (part6 << 8)  | (part7 << 7)  | (part8 << 6)  |
 152         (part9 << 4)  | (part10 << 1) | (part11);
 153
 154     // Select the remaining high-order bits
 155     Addr remaining_bits = bits(addr, std::numeric_limits<Addr>::digits - 1,
 156         offsetBits + 21) << 21;
 157     result = result | remaining_bits;
 158
 159     return result;
 160 }
 161
 162 } // namespace BloomFilter
 163
 164 BloomFilter::Bulk*
 165 BloomFilterBulkParams::create()
 166 {
 167     return new BloomFilter::Bulk(this);
 168 }
 169