6189230202
Summary: Closes https://github.com/facebook/rocksdb/pull/2589 Differential Revision: D5431502 Pulled By: siying fbshipit-source-id: 8ebf8c87883daa9daa54b2303d11ce01ab1f6f75
82 lines
2.3 KiB
C++
82 lines
2.3 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
|
|
// This source code is licensed under both the GPLv2 (found in the
|
|
// COPYING file in the root directory) and Apache 2.0 License
|
|
// (found in the LICENSE.Apache file in the root directory).
|
|
//
|
|
// 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"
|
|
|
|
#include <algorithm>
|
|
#include "rocksdb/slice.h"
|
|
#include "rocksdb/slice_transform.h"
|
|
|
|
namespace rocksdb {
|
|
|
|
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);
|
|
}
|
|
|
|
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 nullptr;
|
|
}
|
|
|
|
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 nullptr;
|
|
}
|
|
|
|
} // namespace rocksdb
|