57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
// Copyright (c) 2016 The WebM project authors. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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#include "src/size_parser.h"
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#include <cassert>
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#include <cstdint>
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#include <limits>
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#include "src/bit_utils.h"
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#include "src/parser_utils.h"
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#include "webm/element.h"
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#include "webm/reader.h"
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#include "webm/status.h"
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namespace webm {
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// Spec references:
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// http://matroska.org/technical/specs/index.html#EBML_ex
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// https://github.com/Matroska-Org/ebml-specification/blob/master/specification.markdown#element-data-size
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Status SizeParser::Feed(Callback* callback, Reader* reader,
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std::uint64_t* num_bytes_read) {
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assert(callback != nullptr);
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assert(reader != nullptr);
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assert(num_bytes_read != nullptr);
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// Within the EBML header, the size can be encoded with 1-4 octets. After
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// the EBML header, the size can be encoded with 1-8 octets (though not more
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// than EBMLMaxSizeLength).
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Status status = uint_parser_.Feed(callback, reader, num_bytes_read);
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if (status.code == Status::kInvalidElementValue) {
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status.code = Status::kInvalidElementSize;
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}
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return status;
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}
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std::uint64_t SizeParser::size() const {
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// If all data bits are set, then it represents an unknown element size.
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const std::uint64_t data_bits =
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std::numeric_limits<std::uint64_t>::max() >>
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(57 - 7 * (uint_parser_.encoded_length() - 1));
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if (uint_parser_.value() == data_bits) {
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return kUnknownElementSize;
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}
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return uint_parser_.value();
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}
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} // namespace webm
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