1 // Copyright 2021 gRPC authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //     http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 #ifndef GRPC_SRC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_HPACK_CONSTANTS_H
16 #define GRPC_SRC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_HPACK_CONSTANTS_H
17 
18 #include <grpc/support/port_platform.h>
19 
20 #include <cstddef>
21 #include <cstdint>
22 
23 namespace grpc_core {
24 namespace hpack_constants {
25 // Per entry overhead bytes as per the spec
26 static constexpr uint32_t kEntryOverhead = 32;
27 // Initial table size as per the spec
28 static constexpr uint32_t kInitialTableSize = 4096;
29 
30 // last index in the static table
31 static constexpr uint32_t kLastStaticEntry = 61;
32 
EntriesForBytes(uint32_t bytes)33 static constexpr uint32_t EntriesForBytes(uint32_t bytes) noexcept {
34   return (bytes + kEntryOverhead - 1) / kEntryOverhead;
35 }
36 
SizeForEntry(size_t key_length,size_t value_length)37 static constexpr size_t SizeForEntry(size_t key_length,
38                                      size_t value_length) noexcept {
39   return key_length + value_length + kEntryOverhead;
40 }
41 
42 static constexpr uint32_t kInitialTableEntries =
43     EntriesForBytes(kInitialTableSize);
44 }  // namespace hpack_constants
45 }  // namespace grpc_core
46 
47 #endif  // GRPC_SRC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_HPACK_CONSTANTS_H
48