aboutsummaryrefslogtreecommitdiff
path: root/src/processor/contained_range_map-inl.h
blob: 3a1c74dbdb41ccefa8fa8d1713b9b1a1ec333348 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
// Copyright (c) 2006, Google Inc.
// 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 Google Inc. 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.

// contained_range_map-inl.h: Hierarchically-organized range map implementation.
//
// See contained_range_map.h for documentation.
//
// Author: Mark Mentovai

#ifndef PROCESSOR_CONTAINED_RANGE_MAP_INL_H__
#define PROCESSOR_CONTAINED_RANGE_MAP_INL_H__


#include "processor/contained_range_map.h"


namespace google_airbag {


template<typename AddressType, typename EntryType>
ContainedRangeMap<AddressType, EntryType>::~ContainedRangeMap() {
  // Clear frees the children pointed to by the map, and frees the map itself.
  Clear();
}


template<typename AddressType, typename EntryType>
bool ContainedRangeMap<AddressType, EntryType>::StoreRange(
    const AddressType &base, const AddressType &size, const EntryType &entry) {
  AddressType high = base + size - 1;

  // Check for undersize or overflow.
  if (size <= 0 || high < base)
    return false;

  if (!map_)
    map_ = new AddressToRangeMap();

  MapIterator iterator_base = map_->lower_bound(base);
  MapIterator iterator_high = map_->lower_bound(high);
  MapConstIterator iterator_end = map_->end();

  if (iterator_base == iterator_high && iterator_base != iterator_end &&
      base >= iterator_base->second->base_) {
    // The new range is entirely within an existing child range.

    // If the new range's geometry is exactly equal to an existing child
    // range's, it violates the containment rules, and an attempt to store
    // it must fail.  iterator_base->first contains the key, which was the
    // containing child's high address.
    if (iterator_base->second->base_ == base && iterator_base->first == high)
      return false;

    // Pass the new range on to the child to attempt to store.
    return iterator_base->second->StoreRange(base, size, entry);
  }

  // iterator_high might refer to an irrelevant range: one whose base address
  // is higher than the new range's high address.  Set contains_high to true
  // only if iterator_high refers to a range that is at least partially
  // within the new range.
  bool contains_high = iterator_high != iterator_end &&
                       high >= iterator_high->second->base_;

  // If the new range encompasses any existing child ranges, it must do so
  // fully.  Partial containment isn't allowed.
  if ((iterator_base != iterator_end && base > iterator_base->second->base_) ||
      (contains_high && high < iterator_high->first)) {
    return false;
  }

  // When copying and erasing contained ranges, the "end" iterator needs to
  // point one past the last item of the range to copy.  If contains_high is
  // false, the iterator's already in the right place; the increment is safe
  // because contains_high can't be true if iterator_high == iterator_end.
  if (contains_high)
    ++iterator_high;

  // Optimization: if the iterators are equal, no child ranges would be
  // moved.  Create the new child range with a NULL map to conserve space
  // in leaf nodes, of which there will be many.
  AddressToRangeMap *child_map = NULL;

  if (iterator_base != iterator_high) {
    // The children of this range that are contained by the new range must
    // be transferred over to the new range.  Create the new child range map
    // and copy the pointers to range maps it should contain into it.
    child_map = new AddressToRangeMap(iterator_base, iterator_high);

    // Remove the copied child pointers from this range's map of children.
    map_->erase(iterator_base, iterator_high);
  }

  // Store the new range in the map by its high address.  Any children that
  // the new child range contains were formerly children of this range but
  // are now this range's grandchildren.  Ownership of these is transferred
  // to the new child range.
  map_->insert(MapValue(high,
                        new ContainedRangeMap(base, entry, child_map)));
  return true;
}


template<typename AddressType, typename EntryType>
bool ContainedRangeMap<AddressType, EntryType>::RetrieveRange(
    const AddressType &address, EntryType *entry) const {
  if (!entry || !map_)
    return false;

  // Get an iterator to the child range whose high address is equal to or
  // greater than the supplied address.  If the supplied address is higher
  // than all of the high addresses in the range, then this range does not
  // contain a child at address, so return false.  If the supplied address
  // is lower than the base address of the child range, then it is not within
  // the child range, so return false.
  MapConstIterator iterator = map_->lower_bound(address);
  if (iterator == map_->end() || address < iterator->second->base_)
    return false;

  // The child in iterator->second contains the specified address.  Find out
  // if it has a more-specific descendant that also contains it.  If it does,
  // it will set |entry| appropriately.  If not, set |entry| to the child.
  if (!iterator->second->RetrieveRange(address, entry))
    *entry = iterator->second->entry_;

  return true;
}


template<typename AddressType, typename EntryType>
void ContainedRangeMap<AddressType, EntryType>::Clear() {
  if (map_) {
    MapConstIterator end = map_->end();
    for (MapConstIterator child = map_->begin(); child != end; ++child)
      delete child->second;

    delete map_;
    map_ = NULL;
  }
}


}  // namespace google_airbag


#endif  // PROCESSOR_CONTAINED_RANGE_MAP_INL_H__