259 lines
10 KiB
C++
259 lines
10 KiB
C++
#include "./matroskaseekinfo.h"
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#include "./matroskaid.h"
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#include "../diagnostics.h"
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#include "../exceptions.h"
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#include <c++utilities/conversion/binaryconversion.h>
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#include <c++utilities/conversion/stringbuilder.h>
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#include <string>
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using namespace std;
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using namespace CppUtilities;
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namespace TagParser {
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/*!
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* \class TagParser::MatroskaSeekInfo
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* \brief The MatroskaSeekInfo class helps parsing and making "SeekHead"-elements.
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*/
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/*!
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* \brief Shifts all offsets greater or equal than \a start by \a amount bytes.
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*/
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void MatroskaSeekInfo::shift(std::uint64_t start, std::int64_t amount)
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{
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for (auto &info : m_info) {
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if (get<1>(info) >= start) {
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if (amount > 0) {
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get<1>(info) += static_cast<std::uint64_t>(amount);
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} else {
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get<1>(info) -= static_cast<std::uint64_t>(-amount);
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}
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}
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}
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}
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/*!
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* \brief Parses the specified \a seekHeadElement and populates info() with the gathered information.
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* \throws Throws ios_base::failure when an IO error occurs.
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* \throws Throws Failure or a derived exception when a parsing error occurs.
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* \remarks
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* - The object does not take ownership over the specified \a seekHeadElement.
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* - Possibly previously parsed info() is not cleared. So subsequent calls can be used to gather seek
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* information from multiple seek head elements. Use clear() manually if that is not wanted.
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* - If the specified \a seekHeadElement references another seek head element the referenced seek head
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* element is parsed as well. One can set \a maxIndirection to 0 to prevent that or even increase the value
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* to allow following references even more deeply. References to elements which have already been visited
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* are never followed, though.
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*/
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void MatroskaSeekInfo::parse(EbmlElement *seekHeadElement, Diagnostics &diag, size_t maxIndirection)
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{
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static const string context("parsing \"SeekHead\"-element");
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m_seekHeadElements.emplace_back(seekHeadElement);
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for (EbmlElement *seekElement = seekHeadElement->firstChild(), *seekIdElement, *seekPositionElement; seekElement;
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seekElement = seekElement->nextSibling()) {
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seekElement->parse(diag);
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switch (seekElement->id()) {
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case MatroskaIds::Seek:
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seekIdElement = seekPositionElement = nullptr;
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for (auto *seekElementChild = seekElement->firstChild(); seekElementChild; seekElementChild = seekElementChild->nextSibling()) {
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seekElementChild->parse(diag);
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switch (seekElementChild->id()) {
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case MatroskaIds::SeekID:
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if (seekIdElement) {
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diag.emplace_back(DiagLevel::Warning,
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"The \"Seek\"-element contains multiple \"SeekID\"-elements. Surplus elements will be ignored.", context);
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}
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seekIdElement = seekElementChild;
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break;
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case MatroskaIds::SeekPosition:
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if (seekPositionElement) {
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diag.emplace_back(DiagLevel::Warning,
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"The \"Seek\"-element contains multiple \"SeekPosition\"-elements. Surplus elements will be ignored.", context);
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}
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seekPositionElement = seekElementChild;
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break;
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case EbmlIds::Crc32:
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case EbmlIds::Void:
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break;
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default:
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diag.emplace_back(DiagLevel::Warning,
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"The element \"" % seekElementChild->idToString()
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+ "\" within the \"Seek\" element is not a \"SeekID\"-element nor a \"SeekPosition\"-element and will be ignored.",
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context);
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}
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}
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if (!seekIdElement || !seekPositionElement) {
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diag.emplace_back(DiagLevel::Warning, "The \"Seek\"-element does not contain a \"SeekID\"- and a \"SeekPosition\"-element.", context);
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break;
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}
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m_info.emplace_back(seekIdElement->readUInteger(), seekPositionElement->readUInteger());
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// follow possibly referenced seek head element
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if (m_info.back().first == MatroskaIds::SeekHead) {
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const auto startOffset = m_info.back().second;
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if (!maxIndirection) {
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diag.emplace_back(DiagLevel::Warning,
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argsToString("Not following reference by \"Seek\"-element at ", seekElement->startOffset(),
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" which points to another \"SeekHead\"-element at ", startOffset, '.'),
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context);
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break;
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}
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auto visited = false;
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for (const auto *const visitedSeekHeadElement : m_seekHeadElements) {
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if (visitedSeekHeadElement->startOffset() == startOffset) {
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diag.emplace_back(DiagLevel::Warning,
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argsToString("The \"Seek\"-element at ", seekElement->startOffset(), " contains a loop to the \"SeekHead\"-element at ",
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visitedSeekHeadElement->startOffset(), '.'),
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context);
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visited = true;
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break;
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}
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}
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if (visited) {
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break;
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}
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m_additionalSeekHeadElements.emplace_back(make_unique<EbmlElement>(seekHeadElement->container(), startOffset));
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parse(m_additionalSeekHeadElements.back().get(), diag, maxIndirection - 1);
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}
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break;
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case EbmlIds::Crc32:
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case EbmlIds::Void:
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break;
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default:
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diag.emplace_back(
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DiagLevel::Warning, "The element " % seekElement->idToString() + " is not a seek element and will be ignored.", context);
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}
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}
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if (m_info.empty()) {
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diag.emplace_back(DiagLevel::Warning, "No seek information found.", context);
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}
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}
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/*!
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* \brief Writes a "SeekHead" element for the current instance to the specified \a stream.
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* \param stream Specifies the stream to write the "SeekHead" element to.
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* \throws Throws ios_base::failure when an IO error occurs.
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* \throws Throws Failure or a derived exception when a making error occurs.
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*/
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void MatroskaSeekInfo::make(ostream &stream, Diagnostics &diag)
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{
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CPP_UTILITIES_UNUSED(diag)
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std::uint64_t totalSize = 0;
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char buff0[8];
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char buff1[8];
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char buff2[2];
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std::uint8_t sizeLength0, sizeLength1;
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// calculate size
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for (const auto &info : m_info) {
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// "Seek" element + "SeekID" element + "SeekPosition" element
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totalSize += 2u + 1u + (2u + 1u + EbmlElement::calculateIdLength(info.first)) + (2u + 1u + EbmlElement::calculateUIntegerLength(info.second));
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}
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// write ID and size
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BE::getBytes(static_cast<std::uint32_t>(MatroskaIds::SeekHead), buff0);
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stream.write(buff0, 4);
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sizeLength0 = EbmlElement::makeSizeDenotation(totalSize, buff0);
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stream.write(buff0, sizeLength0);
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// write entries
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for (const auto &info : m_info) {
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// make values
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sizeLength0 = EbmlElement::makeId(info.first, buff0);
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sizeLength1 = EbmlElement::makeUInteger(info.second, buff1);
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// "Seek" header
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BE::getBytes(static_cast<std::uint16_t>(MatroskaIds::Seek), buff2);
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stream.write(buff2, 2);
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stream.put(static_cast<char>(0x80 | (2 + 1 + sizeLength0 + 2 + 1 + sizeLength1)));
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// "SeekID" element
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BE::getBytes(static_cast<std::uint16_t>(MatroskaIds::SeekID), buff2);
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stream.write(buff2, 2);
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stream.put(static_cast<char>(0x80 | sizeLength0));
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stream.write(buff0, sizeLength0);
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// "SeekPosition" element
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BE::getBytes(static_cast<std::uint16_t>(MatroskaIds::SeekPosition), buff2);
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stream.write(buff2, 2);
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stream.put(static_cast<char>(0x80 | sizeLength1));
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stream.write(buff1, sizeLength1);
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}
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}
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/*!
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* \brief Returns the minimal number of bytes written when calling the make() method.
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* \remarks The returned value gets invalidated when the object is mutated.
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*/
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std::uint64_t MatroskaSeekInfo::minSize() const
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{
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std::uint64_t maxTotalSize = m_info.size() * (2 + 1 + 2 + 1 + 1 + 2 + 1 + 1);
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return 4 + EbmlElement::calculateSizeDenotationLength(maxTotalSize) + maxTotalSize;
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}
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/*!
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* \brief Returns the maximal number of bytes written when calling the make() method.
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* \remarks The returned value gets invalidated when the object is mutated.
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*/
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std::uint64_t MatroskaSeekInfo::maxSize() const
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{
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std::uint64_t maxTotalSize = m_info.size() * (2 + 1 + 2 + 1 + 4 + 2 + 1 + 8);
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return 4 + EbmlElement::calculateSizeDenotationLength(maxTotalSize) + maxTotalSize;
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}
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/*!
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* \brief Returns the number of bytes which will be written when calling the make() method.
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* \remarks The returned value gets invalidated when the object is mutated.
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*/
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std::uint64_t MatroskaSeekInfo::actualSize() const
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{
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std::uint64_t totalSize = 0;
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for (const auto &info : m_info) {
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// "Seek" element + "SeekID" element + "SeekPosition" element
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totalSize
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+= 2u + 1u + (2 + 1 + EbmlElement::calculateIdLength(get<0>(info))) + (2u + 1u + EbmlElement::calculateUIntegerLength(get<1>(info)));
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}
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return totalSize += 4u + EbmlElement::calculateSizeDenotationLength(totalSize);
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}
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/*!
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* \brief Pushes the specified \a offset of an element with the specified \a id to the info.
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*
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* If there is an existing entry with the same \a id and \a index the existing entry will be
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* updated and no new entry created.
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*
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* \returns Returns an indication whether the actualSize() has changed.
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*/
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bool MatroskaSeekInfo::push(unsigned int index, EbmlElement::IdentifierType id, std::uint64_t offset)
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{
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unsigned int currentIndex = 0;
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for (auto &entry : info()) {
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if (get<0>(entry) == id) {
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if (index == currentIndex) {
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bool sizeUpdated = EbmlElement::calculateUIntegerLength(get<1>(entry)) != EbmlElement::calculateUIntegerLength(offset);
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get<1>(entry) = offset;
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return sizeUpdated;
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}
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++currentIndex;
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}
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}
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info().emplace_back(id, offset);
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return true;
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}
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/*!
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* \brief Resets the object to its initial state.
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*/
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void MatroskaSeekInfo::clear()
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{
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m_seekHeadElements.clear();
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m_additionalSeekHeadElements.clear();
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m_info.clear();
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}
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} // namespace TagParser
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