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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;
}
}
const char* GetLengthPrefixedSlice(const char* p, const char* limit,
Slice* result) {
uint32_t len;
p = GetVarint32Ptr(p, limit, &len);
if (p == nullptr) return nullptr;
if (p + len > limit) return nullptr;
*result = Slice(p, len);
return p + len;
}
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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