84 lines
2.3 KiB
C++
84 lines
2.3 KiB
C++
// Copyright 2020 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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#include "pw_stream/interval_reader.h"
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#include "pw_assert/check.h"
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namespace pw::stream {
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StatusWithSize IntervalReader::DoRead(ByteSpan destination) {
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if (!source_reader_) {
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return StatusWithSize(Status::FailedPrecondition(), 0);
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}
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if (!status_.ok()) {
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return StatusWithSize(status_, 0);
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}
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if (current_ == end_) {
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return StatusWithSize::OutOfRange();
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}
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// Seek the source reader to the `current_` offset of this IntervalReader
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// before reading.
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Status status = source_reader_->Seek(current_, Whence::kBeginning);
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if (!status.ok()) {
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return StatusWithSize(status, 0);
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}
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size_t to_read = std::min(destination.size(), end_ - current_);
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Result<ByteSpan> res = source_reader_->Read(destination.first(to_read));
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if (!res.ok()) {
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return StatusWithSize(res.status(), 0);
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}
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current_ += res.value().size();
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return StatusWithSize(res.value().size());
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}
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Status IntervalReader::DoSeek(ptrdiff_t offset, Whence origin) {
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ptrdiff_t absolute_position = std::numeric_limits<ptrdiff_t>::min();
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// Convert from the position within the interval to the position within the
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// source reader stream.
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switch (origin) {
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case Whence::kBeginning:
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absolute_position = offset + start_;
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break;
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case Whence::kCurrent:
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absolute_position = current_ + offset;
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break;
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case Whence::kEnd:
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absolute_position = end_ + offset;
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break;
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}
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if (absolute_position < 0) {
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return Status::InvalidArgument();
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}
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if (static_cast<size_t>(absolute_position) < start_ ||
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static_cast<size_t>(absolute_position) > end_) {
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return Status::InvalidArgument();
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}
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current_ = absolute_position;
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return OkStatus();
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}
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}; // namespace pw::stream
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