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//
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
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