GRPC Core  9.0.0
varint.h
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1 /*
2  *
3  * Copyright 2015 gRPC authors.
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  *
17  */
18 
19 #ifndef GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_VARINT_H
20 #define GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_VARINT_H
21 
23 
24 /* Helpers for hpack varint encoding */
25 
26 /* length of a value that needs varint tail encoding (it's bigger than can be
27  bitpacked into the opcode byte) - returned value includes the length of the
28  opcode byte */
29 uint32_t grpc_chttp2_hpack_varint_length(uint32_t tail_value);
30 
31 void grpc_chttp2_hpack_write_varint_tail(uint32_t tail_value, uint8_t* target,
32  uint32_t tail_length);
33 
34 /* maximum value that can be bitpacked with the opcode if the opcode has a
35  prefix
36  of length prefix_bits */
37 #define GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits) \
38  ((uint32_t)((1 << (8 - (prefix_bits))) - 1))
39 
40 /* length required to bitpack a value */
41 #define GRPC_CHTTP2_VARINT_LENGTH(n, prefix_bits) \
42  ((n) < GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits) \
43  ? 1u \
44  : grpc_chttp2_hpack_varint_length( \
45  (n)-GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits)))
46 
47 #define GRPC_CHTTP2_WRITE_VARINT(n, prefix_bits, prefix_or, target, length) \
48  do { \
49  uint8_t* tgt = target; \
50  if ((length) == 1u) { \
51  (tgt)[0] = (uint8_t)((prefix_or) | (n)); \
52  } else { \
53  (tgt)[0] = \
54  (prefix_or) | (uint8_t)GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits); \
55  grpc_chttp2_hpack_write_varint_tail( \
56  (n)-GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits), (tgt) + 1, (length)-1); \
57  } \
58  } while (0)
59 
60 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_TRANSPORT_VARINT_H */
void grpc_chttp2_hpack_write_varint_tail(uint32_t tail_value, uint8_t *target, uint32_t tail_length)
Definition: varint.cc:37
uint32_t grpc_chttp2_hpack_varint_length(uint32_t tail_value)
Definition: varint.cc:23