| // 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 |