113 lines
3.9 KiB
C
113 lines
3.9 KiB
C
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/*
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* RowVisitor.h
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* ------------
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* Purpose: Class for recording which rows of a song has already been visited, used for detecting when a module starts to loop.
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* Notes : See implementation file.
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* Authors: OpenMPT Devs
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* The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
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*/
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#pragma once
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#include "openmpt/all/BuildSettings.hpp"
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#include "mpt/base/span.hpp"
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#include "Snd_defs.h"
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#include <map>
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OPENMPT_NAMESPACE_BEGIN
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#if defined(MPT_BUILD_DEBUG) || defined(MPT_BUILD_FUZZER)
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#define MPT_VERIFY_ROWVISITOR_LOOPSTATE
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#endif // MPT_BUILD_DEBUG || MPT_BUILD_FUZZER
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class CSoundFile;
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class ModSequence;
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struct ModChannel;
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class RowVisitor
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{
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protected:
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using ChannelStates = mpt::span<const ModChannel>;
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class LoopState
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{
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static constexpr uint64 FNV1a_BASIS = 14695981039346656037ull;
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static constexpr uint64 FNV1a_PRIME = 1099511628211ull;
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uint64 m_hash = FNV1a_BASIS;
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#ifdef MPT_VERIFY_ROWVISITOR_LOOPSTATE
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std::vector<std::pair<uint8, uint8>> m_counts; // Actual loop counts to verify equality of hash-based implementation
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#endif
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public:
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LoopState() = default;
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LoopState(const ChannelStates &chnState, const bool ignoreRow);
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LoopState(const LoopState &) = default;
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LoopState(LoopState&&) = default;
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LoopState &operator=(const LoopState &) = default;
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LoopState &operator=(LoopState&&) = default;
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[[nodiscard]] bool operator==(const LoopState &other) const noexcept
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{
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#ifdef MPT_VERIFY_ROWVISITOR_LOOPSTATE
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if((m_counts == other.m_counts) != (m_hash == other.m_hash))
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std::abort();
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#endif
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return m_hash == other.m_hash;
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}
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[[nodiscard]] bool HasLoops() const noexcept
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{
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#ifdef MPT_VERIFY_ROWVISITOR_LOOPSTATE
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if(m_counts.empty() != (m_hash == FNV1a_BASIS))
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std::abort();
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#endif
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return m_hash != FNV1a_BASIS;
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}
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};
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using LoopStateSet = std::vector<LoopState>;
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// Stores for every (order, row) combination in the sequence if it has been visited or not.
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std::vector<std::vector<bool>> m_visitedRows;
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// Map for each row that's part of a pattern loop which loop states have been visited. Held in a separate data structure because it is sparse data in typical modules.
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std::map<std::pair<ORDERINDEX, ROWINDEX>, LoopStateSet> m_visitedLoopStates;
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const CSoundFile &m_sndFile;
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ROWINDEX m_rowsSpentInLoops = 0;
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const SEQUENCEINDEX m_sequence;
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public:
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RowVisitor(const CSoundFile &sndFile, SEQUENCEINDEX sequence = SEQUENCEINDEX_INVALID);
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void MoveVisitedRowsFrom(RowVisitor &other) noexcept;
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// Resize / Clear the row vector.
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// If reset is true, the vector is not only resized to the required dimensions, but also completely cleared (i.e. all visited rows are unset).
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void Initialize(bool reset);
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// Mark an order/row combination as visited and returns true if it was visited before.
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bool Visit(ORDERINDEX ord, ROWINDEX row, const ChannelStates &chnState, bool ignoreRow);
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// Find the first row that has not been played yet.
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// The order and row is stored in the order and row variables on success, on failure they contain invalid values.
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// If onlyUnplayedPatterns is true (default), only completely unplayed patterns are considered, otherwise a song can start anywhere.
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// Function returns true on success.
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[[nodiscard]] bool GetFirstUnvisitedRow(ORDERINDEX &order, ROWINDEX &row, bool onlyUnplayedPatterns) const;
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// Pattern loops can stack up exponentially, which can cause an effectively infinite amount of time to be spent on evaluating them.
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// If this function returns true, module evaluation should be aborted because the pattern loops appear to be too complex.
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[[nodiscard]] bool ModuleTooComplex(ROWINDEX threshold) const noexcept { return m_rowsSpentInLoops >= threshold; }
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void ResetComplexity() { m_rowsSpentInLoops = 0; }
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protected:
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// Get the needed vector size for a given pattern.
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[[nodiscard]] ROWINDEX VisitedRowsVectorSize(PATTERNINDEX pattern) const noexcept;
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[[nodiscard]] const ModSequence &Order() const;
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};
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OPENMPT_NAMESPACE_END
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