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- /*
- * Copyright 2012-present Facebook, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- #pragma once
- #include <stddef.h>
- #include <stdint.h>
- namespace folly {
- template <typename T>
- class GroupVarint;
- namespace detail {
- template <typename T>
- struct GroupVarintTraits;
- template <>
- struct GroupVarintTraits<uint32_t> {
- enum : uint32_t {
- kGroupSize = 4,
- kHeaderSize = 1,
- };
- };
- template <>
- struct GroupVarintTraits<uint64_t> {
- enum : uint32_t {
- kGroupSize = 5,
- kHeaderSize = 2,
- };
- };
- template <typename T>
- class GroupVarintBase {
- protected:
- typedef GroupVarintTraits<T> Traits;
- enum : uint32_t { kHeaderSize = Traits::kHeaderSize };
- public:
- typedef T type;
- /**
- * Number of integers encoded / decoded in one pass.
- */
- enum : uint32_t { kGroupSize = Traits::kGroupSize };
- /**
- * Maximum encoded size.
- */
- enum : uint32_t { kMaxSize = kHeaderSize + sizeof(type) * kGroupSize };
- /**
- * Maximum size for n values.
- */
- static size_t maxSize(size_t n) {
- // Full groups
- size_t total = (n / kGroupSize) * kFullGroupSize;
- // Incomplete last group, if any
- n %= kGroupSize;
- if (n) {
- total += kHeaderSize + n * sizeof(type);
- }
- return total;
- }
- /**
- * Size of n values starting at p.
- */
- static size_t totalSize(const T* p, size_t n) {
- size_t size = 0;
- for (; n >= kGroupSize; n -= kGroupSize, p += kGroupSize) {
- size += Derived::size(p);
- }
- if (n) {
- size += Derived::partialSize(p, n);
- }
- return size;
- }
- private:
- typedef GroupVarint<T> Derived;
- enum { kFullGroupSize = kHeaderSize + kGroupSize * sizeof(type) };
- };
- } // namespace detail
- } // namespace folly
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