Nelze vybrat více než 25 témat
Téma musí začínat písmenem nebo číslem, může obsahovat pomlčky („-“) a může být dlouhé až 35 znaků.
194 řádky
4.8 KiB
194 řádky
4.8 KiB
// 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 EncodeFixed32(char* buf, uint32_t value) {
|
|
if (port::kLittleEndian) {
|
|
memcpy(buf, &value, sizeof(value));
|
|
} else {
|
|
buf[0] = value & 0xff;
|
|
buf[1] = (value >> 8) & 0xff;
|
|
buf[2] = (value >> 16) & 0xff;
|
|
buf[3] = (value >> 24) & 0xff;
|
|
}
|
|
}
|
|
|
|
void EncodeFixed64(char* buf, uint64_t value) {
|
|
if (port::kLittleEndian) {
|
|
memcpy(buf, &value, sizeof(value));
|
|
} else {
|
|
buf[0] = value & 0xff;
|
|
buf[1] = (value >> 8) & 0xff;
|
|
buf[2] = (value >> 16) & 0xff;
|
|
buf[3] = (value >> 24) & 0xff;
|
|
buf[4] = (value >> 32) & 0xff;
|
|
buf[5] = (value >> 40) & 0xff;
|
|
buf[6] = (value >> 48) & 0xff;
|
|
buf[7] = (value >> 56) & 0xff;
|
|
}
|
|
}
|
|
|
|
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
|
|
unsigned char* ptr = reinterpret_cast<unsigned char*>(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;
|
|
unsigned char* ptr = reinterpret_cast<unsigned char*>(dst);
|
|
while (v >= B) {
|
|
*(ptr++) = (v & (B-1)) | B;
|
|
v >>= 7;
|
|
}
|
|
*(ptr++) = static_cast<unsigned char>(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 unsigned char*>(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 NULL;
|
|
}
|
|
|
|
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 == NULL) {
|
|
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 unsigned char*>(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 NULL;
|
|
}
|
|
|
|
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 == NULL) {
|
|
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 == NULL) return NULL;
|
|
if (p + len > limit) return NULL;
|
|
*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
|