| // Copyright 2020 The Pigweed Authors |
| // |
| // 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 |
| // |
| // https://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. |
| |
| #include "pw_stream/interval_reader.h" |
| |
| #include "pw_assert/check.h" |
| |
| namespace pw::stream { |
| |
| StatusWithSize IntervalReader::DoRead(ByteSpan destination) { |
| if (!source_reader_) { |
| return StatusWithSize(Status::FailedPrecondition(), 0); |
| } |
| |
| if (!status_.ok()) { |
| return StatusWithSize(status_, 0); |
| } |
| |
| if (current_ == end_) { |
| return StatusWithSize::OutOfRange(); |
| } |
| |
| // Seek the source reader to the `current_` offset of this IntervalReader |
| // before reading. |
| Status status = source_reader_->Seek(current_, Whence::kBeginning); |
| if (!status.ok()) { |
| return StatusWithSize(status, 0); |
| } |
| |
| size_t to_read = std::min(destination.size(), end_ - current_); |
| Result<ByteSpan> res = source_reader_->Read(destination.first(to_read)); |
| if (!res.ok()) { |
| return StatusWithSize(res.status(), 0); |
| } |
| |
| current_ += res.value().size(); |
| return StatusWithSize(res.value().size()); |
| } |
| |
| Status IntervalReader::DoSeek(ptrdiff_t offset, Whence origin) { |
| ptrdiff_t absolute_position = std::numeric_limits<ptrdiff_t>::min(); |
| |
| // Convert from the position within the interval to the position within the |
| // source reader stream. |
| switch (origin) { |
| case Whence::kBeginning: |
| absolute_position = offset + start_; |
| break; |
| |
| case Whence::kCurrent: |
| absolute_position = current_ + offset; |
| break; |
| |
| case Whence::kEnd: |
| absolute_position = end_ + offset; |
| break; |
| } |
| |
| if (absolute_position < 0) { |
| return Status::InvalidArgument(); |
| } |
| |
| if (static_cast<size_t>(absolute_position) < start_ || |
| static_cast<size_t>(absolute_position) > end_) { |
| return Status::InvalidArgument(); |
| } |
| |
| current_ = absolute_position; |
| return OkStatus(); |
| } |
| |
| }; // namespace pw::stream |