1 // Copyright 2024 The Pigweed Authors
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
4 // use this file except in compliance with the License. You may obtain a copy of
5 // the License at
6 //
7 // https://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, WITHOUT
11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12 // License for the specific language governing permissions and limitations under
13 // the License.
14
15 #include "pw_multibuf/stream.h"
16
17 #include <algorithm>
18 #include <cstring>
19
20 #include "pw_status/status.h"
21 #include "pw_status/status_with_size.h"
22 #include "pw_status/try.h"
23 #include "pw_stream/seek.h"
24
25 namespace pw::multibuf {
26
DoWrite(ConstByteSpan data)27 Status Stream::DoWrite(ConstByteSpan data) {
28 while (!data.empty()) {
29 if (iterator_ == multibuf_.end()) {
30 return Status::OutOfRange();
31 }
32
33 Chunk* current_chunk = iterator_.chunk();
34 const size_t remaining_in_chunk =
35 current_chunk->size() - iterator_.byte_index();
36
37 const size_t bytes_to_copy = std::min(data.size(), remaining_in_chunk);
38
39 std::memcpy(current_chunk->data() + iterator_.byte_index(),
40 data.data(),
41 bytes_to_copy);
42
43 data = data.subspan(bytes_to_copy);
44 multibuf_offset_ += bytes_to_copy;
45 iterator_ += bytes_to_copy;
46 }
47
48 return OkStatus();
49 }
50
DoRead(ByteSpan destination)51 StatusWithSize Stream::DoRead(ByteSpan destination) {
52 size_t bytes_written = 0;
53
54 while (!destination.empty()) {
55 if (iterator_ == multibuf_.end()) {
56 if (bytes_written > 0) {
57 return StatusWithSize(bytes_written);
58 }
59 return StatusWithSize::OutOfRange();
60 }
61
62 Chunk* current_chunk = iterator_.chunk();
63 const size_t remaining_in_chunk =
64 current_chunk->size() - iterator_.byte_index();
65
66 const size_t bytes_to_copy =
67 std::min(remaining_in_chunk, destination.size());
68 std::memcpy(destination.data(),
69 current_chunk->data() + iterator_.byte_index(),
70 bytes_to_copy);
71
72 destination = destination.subspan(bytes_to_copy);
73 bytes_written += bytes_to_copy;
74 multibuf_offset_ += bytes_to_copy;
75 iterator_ += bytes_to_copy;
76 }
77
78 return StatusWithSize(bytes_written);
79 }
80
DoSeek(ptrdiff_t offset,Whence origin)81 Status Stream::DoSeek(ptrdiff_t offset, Whence origin) {
82 size_t new_offset = multibuf_offset_;
83 PW_TRY(stream::CalculateSeek(offset, origin, multibuf_.size(), new_offset));
84
85 if (new_offset < multibuf_offset_) {
86 return Status::OutOfRange();
87 }
88
89 iterator_ += new_offset - multibuf_offset_;
90 multibuf_offset_ = new_offset;
91 return iterator_ == multibuf_.end() ? Status::OutOfRange() : OkStatus();
92 }
93
94 } // namespace pw::multibuf
95