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) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "pdf/chunk_stream.h"
#define __STDC_LIMIT_MACROS
#ifdef _WIN32
#include <limits.h>
#else
#include <stdint.h>
#endif
#include <algorithm>
#include "base/basictypes.h"
namespace chrome_pdf {
ChunkStream::ChunkStream() {
}
ChunkStream::~ChunkStream() {
}
void ChunkStream::Clear() {
chunks_.clear();
data_.clear();
}
void ChunkStream::Preallocate(size_t stream_size) {
data_.reserve(stream_size);
}
size_t ChunkStream::GetSize() {
return data_.size();
}
bool ChunkStream::WriteData(size_t offset, void* buffer, size_t size) {
if (SIZE_MAX - size < offset)
return false;
if (data_.size() < offset + size)
data_.resize(offset + size);
memcpy(&data_[offset], buffer, size);
if (chunks_.empty()) {
chunks_[offset] = size;
return true;
}
std::map<size_t, size_t>::iterator start = chunks_.upper_bound(offset);
if (start != chunks_.begin())
--start; // start now points to the key equal or lower than offset.
if (start->first + start->second < offset)
++start; // start element is entirely before current chunk, skip it.
std::map<size_t, size_t>::iterator end = chunks_.upper_bound(offset + size);
if (start == end) { // No chunks to merge.
chunks_[offset] = size;
return true;
}
--end;
size_t new_offset = std::min<size_t>(start->first, offset);
size_t new_size =
std::max<size_t>(end->first + end->second, offset + size) - new_offset;
chunks_.erase(start, ++end);
chunks_[new_offset] = new_size;
return true;
}
bool ChunkStream::ReadData(size_t offset, size_t size, void* buffer) const {
if (!IsRangeAvailable(offset, size))
return false;
memcpy(buffer, &data_[offset], size);
return true;
}
bool ChunkStream::GetMissedRanges(
size_t offset, size_t size,
std::vector<std::pair<size_t, size_t> >* ranges) const {
if (IsRangeAvailable(offset, size))
return false;
ranges->clear();
if (chunks_.empty()) {
ranges->push_back(std::pair<size_t, size_t>(offset, size));
return true;
}
std::map<size_t, size_t>::const_iterator start = chunks_.upper_bound(offset);
if (start != chunks_.begin())
--start; // start now points to the key equal or lower than offset.
if (start->first + start->second < offset)
++start; // start element is entirely before current chunk, skip it.
std::map<size_t, size_t>::const_iterator end =
chunks_.upper_bound(offset + size);
if (start == end) { // No data in the current range available.
ranges->push_back(std::pair<size_t, size_t>(offset, size));
return true;
}
size_t cur_offset = offset;
std::map<size_t, size_t>::const_iterator it;
for (it = start; it != end; ++it) {
if (cur_offset < it->first) {
size_t new_size = it->first - cur_offset;
ranges->push_back(std::pair<size_t, size_t>(cur_offset, new_size));
cur_offset = it->first + it->second;
} else if (cur_offset < it->first + it->second) {
cur_offset = it->first + it->second;
}
}
// Add last chunk.
if (cur_offset < offset + size)
ranges->push_back(std::pair<size_t, size_t>(cur_offset,
offset + size - cur_offset));
return true;
}
bool ChunkStream::IsRangeAvailable(size_t offset, size_t size) const {
if (chunks_.empty())
return false;
if (SIZE_MAX - size < offset)
return false;
std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
if (it == chunks_.begin())
return false; // No chunks includes offset byte.
--it; // Now it starts equal or before offset.
return (it->first + it->second) >= (offset + size);
}
size_t ChunkStream::GetFirstMissingByte() const {
if (chunks_.empty())
return 0;
std::map<size_t, size_t>::const_iterator begin = chunks_.begin();
return begin->first > 0 ? 0 : begin->second;
}
size_t ChunkStream::GetLastByteBefore(size_t offset) const {
if (chunks_.empty())
return 0;
std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
if (it == chunks_.begin())
return 0;
--it;
return it->first + it->second;
}
size_t ChunkStream::GetFirstByteAfter(size_t offset) const {
if (chunks_.empty())
return 0;
std::map<size_t, size_t>::const_iterator it = chunks_.upper_bound(offset);
if (it == chunks_.end())
return data_.size();
return it->first;
}
} // namespace chrome_pdf
|
