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
|
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "util/coding.h"
namespace leveldb {
void PutFixed32(std::string* dst, uint32_t value) {
char buf[sizeof(value)];
EncodeFixed32(buf, value);
dst->append(buf, sizeof(buf));
}
void PutFixed64(std::string* dst, uint64_t value) {
char buf[sizeof(value)];
EncodeFixed64(buf, value);
dst->append(buf, sizeof(buf));
}
char* EncodeVarint32(char* dst, uint32_t v) {
// Operate on characters as unsigneds
uint8_t* ptr = reinterpret_cast<uint8_t*>(dst);
static const int B = 128;
if (v < (1 << 7)) {
*(ptr++) = v;
} else if (v < (1 << 14)) {
*(ptr++) = v | B;
*(ptr++) = v >> 7;
} else if (v < (1 << 21)) {
*(ptr++) = v | B;
*(ptr++) = (v >> 7) | B;
*(ptr++) = v >> 14;
} else if (v < (1 << 28)) {
*(ptr++) = v | B;
*(ptr++) = (v >> 7) | B;
*(ptr++) = (v >> 14) | B;
*(ptr++) = v >> 21;
} else {
*(ptr++) = v | B;
*(ptr++) = (v >> 7) | B;
*(ptr++) = (v >> 14) | B;
*(ptr++) = (v >> 21) | B;
*(ptr++) = v >> 28;
}
return reinterpret_cast<char*>(ptr);
}
void PutVarint32(std::string* dst, uint32_t v) {
char buf[5];
char* ptr = EncodeVarint32(buf, v);
dst->append(buf, ptr - buf);
}
char* EncodeVarint64(char* dst, uint64_t v) {
static const int B = 128;
uint8_t* ptr = reinterpret_cast<uint8_t*>(dst);
while (v >= B) {
*(ptr++) = v | B;
v >>= 7;
}
*(ptr++) = static_cast<uint8_t>(v);
return reinterpret_cast<char*>(ptr);
}
void PutVarint64(std::string* dst, uint64_t v) {
char buf[10];
char* ptr = EncodeVarint64(buf, v);
dst->append(buf, ptr - buf);
}
void PutLengthPrefixedSlice(std::string* dst, const Slice& value) {
PutVarint32(dst, value.size());
dst->append(value.data(), value.size());
}
int VarintLength(uint64_t v) {
int len = 1;
while (v >= 128) {
v >>= 7;
len++;
}
return len;
}
const char* GetVarint32PtrFallback(const char* p, const char* limit,
uint32_t* value) {
uint32_t result = 0;
for (uint32_t shift = 0; shift <= 28 && p < limit; shift += 7) {
uint32_t byte = *(reinterpret_cast<const uint8_t*>(p));
p++;
if (byte & 128) {
// More bytes are present
result |= ((byte & 127) << shift);
} else {
result |= (byte << shift);
*value = result;
return reinterpret_cast<const char*>(p);
}
}
return nullptr;
}
bool GetVarint32(Slice* input, uint32_t* value) {
const char* p = input->data();
const char* limit = p + input->size();
const char* q = GetVarint32Ptr(p, limit, value);
if (q == nullptr) {
return false;
} else {
*input = Slice(q, limit - q);
return true;
}
}
const char* GetVarint64Ptr(const char* p, const char* limit, uint64_t* value) {
uint64_t result = 0;
for (uint32_t shift = 0; shift <= 63 && p < limit; shift += 7) {
uint64_t byte = *(reinterpret_cast<const uint8_t*>(p));
p++;
if (byte & 128) {
// More bytes are present
result |= ((byte & 127) << shift);
} else {
result |= (byte << shift);
*value = result;
return reinterpret_cast<const char*>(p);
}
}
return nullptr;
}
bool GetVarint64(Slice* input, uint64_t* value) {
const char* p = input->data();
const char* limit = p + input->size();
const char* q = GetVarint64Ptr(p, limit, value);
if (q == nullptr) {
return false;
} else {
*input = Slice(q, limit - q);
return true;
}
}
bool GetLengthPrefixedSlice(Slice* input, Slice* result) {
uint32_t len;
if (GetVarint32(input, &len) && input->size() >= len) {
*result = Slice(input->data(), len);
input->remove_prefix(len);
return true;
} else {
return false;
}
}
} // namespace leveldb
|
