mirror of
https://github.com/WinampDesktop/winamp.git
synced 2024-12-12 10:51:01 -05:00
267 lines
9.3 KiB
C++
267 lines
9.3 KiB
C++
/*
|
|
* RowVisitor.cpp
|
|
* --------------
|
|
* Purpose: Class for recording which rows of a song has already been visited, used for detecting when a module starts to loop.
|
|
* Notes : The class keeps track of rows that have been visited by the player before.
|
|
* This way, we can tell when the module starts to loop, i.e. we can determine the song length,
|
|
* or find out that a given point of the module can never be reached.
|
|
*
|
|
* In some module formats, infinite loops can be achieved through pattern loops (e.g. E60 / E61 / E61 in one channel of a ProTracker MOD).
|
|
* To detect such loops, we store a set of loop counts across all channels encountered for each row.
|
|
* As soon as a set of loop counts is encountered twice for a specific row, we know that the track ends up in an infinite loop.
|
|
* As a result of this design, it is safe to evaluate pattern loops in CSoundFile::GetLength.
|
|
* Authors: OpenMPT Devs
|
|
* The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
|
|
*/
|
|
|
|
|
|
#include "stdafx.h"
|
|
#include "RowVisitor.h"
|
|
#include "Sndfile.h"
|
|
|
|
OPENMPT_NAMESPACE_BEGIN
|
|
|
|
RowVisitor::LoopState::LoopState(const ChannelStates &chnState, const bool ignoreRow)
|
|
{
|
|
// Rather than storing the exact loop count vector, we compute a FNV-1a 64-bit hash of it.
|
|
// This means we can store the loop state in a small and fixed amount of memory.
|
|
// In theory there is the possibility of hash collisions for different loop states, but in practice,
|
|
// the relevant inputs for the hashing algorithm are extremely unlikely to produce collisions.
|
|
// There may be better hashing algorithms, but many of them are much more complex and cannot be applied easily in an incremental way.
|
|
uint64 hash = FNV1a_BASIS;
|
|
if(ignoreRow)
|
|
{
|
|
hash = (hash ^ 0xFFu) * FNV1a_PRIME;
|
|
#ifdef MPT_VERIFY_ROWVISITOR_LOOPSTATE
|
|
m_counts.emplace_back(uint8(0xFF), uint8(0xFF));
|
|
#endif
|
|
}
|
|
|
|
for(size_t chn = 0; chn < chnState.size(); chn++)
|
|
{
|
|
if(chnState[chn].nPatternLoopCount)
|
|
{
|
|
static_assert(MAX_BASECHANNELS <= 256, "Channel index cannot be used as byte input for hash generator");
|
|
static_assert(sizeof(chnState[0].nPatternLoopCount) <= sizeof(uint8), "Loop count cannot be used as byte input for hash generator");
|
|
hash = (hash ^ chn) * FNV1a_PRIME;
|
|
hash = (hash ^ chnState[chn].nPatternLoopCount) * FNV1a_PRIME;
|
|
#ifdef MPT_VERIFY_ROWVISITOR_LOOPSTATE
|
|
m_counts.emplace_back(static_cast<uint8>(chn), chnState[chn].nPatternLoopCount);
|
|
#endif
|
|
}
|
|
}
|
|
m_hash = hash;
|
|
}
|
|
|
|
|
|
RowVisitor::RowVisitor(const CSoundFile &sndFile, SEQUENCEINDEX sequence)
|
|
: m_sndFile(sndFile)
|
|
, m_sequence(sequence)
|
|
{
|
|
Initialize(true);
|
|
}
|
|
|
|
|
|
void RowVisitor::MoveVisitedRowsFrom(RowVisitor &other) noexcept
|
|
{
|
|
m_visitedRows = std::move(other.m_visitedRows);
|
|
m_visitedLoopStates = std::move(other.m_visitedLoopStates);
|
|
}
|
|
|
|
|
|
const ModSequence &RowVisitor::Order() const
|
|
{
|
|
if(m_sequence >= m_sndFile.Order.GetNumSequences())
|
|
return m_sndFile.Order();
|
|
else
|
|
return m_sndFile.Order(m_sequence);
|
|
}
|
|
|
|
|
|
// Resize / clear the row vector.
|
|
// If reset is true, the vector is not only resized to the required dimensions, but also completely cleared (i.e. all visited rows are reset).
|
|
void RowVisitor::Initialize(bool reset)
|
|
{
|
|
auto &order = Order();
|
|
const ORDERINDEX endOrder = order.GetLengthTailTrimmed();
|
|
m_visitedRows.resize(endOrder);
|
|
if(reset)
|
|
{
|
|
m_visitedLoopStates.clear();
|
|
m_rowsSpentInLoops = 0;
|
|
}
|
|
|
|
std::vector<uint8> loopCount;
|
|
std::vector<ORDERINDEX> visitedPatterns(m_sndFile.Patterns.GetNumPatterns(), ORDERINDEX_INVALID);
|
|
for(ORDERINDEX ord = 0; ord < endOrder; ord++)
|
|
{
|
|
const PATTERNINDEX pat = order[ord];
|
|
const ROWINDEX numRows = VisitedRowsVectorSize(pat);
|
|
auto &visitedRows = m_visitedRows[ord];
|
|
|
|
if(reset)
|
|
visitedRows.assign(numRows, false);
|
|
else
|
|
visitedRows.resize(numRows, false);
|
|
|
|
if(!order.IsValidPat(ord))
|
|
continue;
|
|
|
|
const ROWINDEX startRow = std::min(static_cast<ROWINDEX>(reset ? 0 : visitedRows.size()), numRows);
|
|
auto insertionHint = m_visitedLoopStates.end();
|
|
|
|
if(visitedPatterns[pat] != ORDERINDEX_INVALID)
|
|
{
|
|
// We visited this pattern before, copy over the results
|
|
const auto begin = m_visitedLoopStates.lower_bound({visitedPatterns[pat], startRow});
|
|
const auto end = (begin != m_visitedLoopStates.end()) ? m_visitedLoopStates.lower_bound({visitedPatterns[pat], numRows}) : m_visitedLoopStates.end();
|
|
for(auto pos = begin; pos != end; ++pos)
|
|
{
|
|
LoopStateSet loopStates;
|
|
loopStates.reserve(pos->second.capacity());
|
|
insertionHint = ++m_visitedLoopStates.insert_or_assign(insertionHint, {ord, pos->first.second}, std::move(loopStates));
|
|
}
|
|
continue;
|
|
}
|
|
|
|
// Pre-allocate loop count state
|
|
const auto &pattern = m_sndFile.Patterns[pat];
|
|
loopCount.assign(pattern.GetNumChannels(), 0);
|
|
for(ROWINDEX i = numRows; i != startRow; i--)
|
|
{
|
|
const ROWINDEX row = i - 1;
|
|
uint32 maxLoopStates = 1;
|
|
auto m = pattern.GetRow(row);
|
|
// Break condition: If it's more than 16, it's probably wrong :) exact loop count depends on how loops overlap.
|
|
for(CHANNELINDEX chn = 0; chn < pattern.GetNumChannels() && maxLoopStates < 16; chn++, m++)
|
|
{
|
|
auto count = loopCount[chn];
|
|
if((m->command == CMD_S3MCMDEX && (m->param & 0xF0) == 0xB0) || (m->command == CMD_MODCMDEX && (m->param & 0xF0) == 0x60))
|
|
{
|
|
loopCount[chn] = (m->param & 0x0F);
|
|
if(loopCount[chn])
|
|
count = loopCount[chn];
|
|
}
|
|
if(count)
|
|
maxLoopStates *= (count + 1);
|
|
}
|
|
if(maxLoopStates > 1)
|
|
{
|
|
LoopStateSet loopStates;
|
|
loopStates.reserve(maxLoopStates);
|
|
insertionHint = m_visitedLoopStates.insert_or_assign(insertionHint, {ord, row}, std::move(loopStates));
|
|
}
|
|
}
|
|
// Only use this order as a blueprint for other orders using the same pattern if we fully parsed the pattern.
|
|
if(startRow == 0)
|
|
visitedPatterns[pat] = ord;
|
|
}
|
|
}
|
|
|
|
|
|
// Mark an order/row combination as visited and returns true if it was visited before.
|
|
bool RowVisitor::Visit(ORDERINDEX ord, ROWINDEX row, const ChannelStates &chnState, bool ignoreRow)
|
|
{
|
|
auto &order = Order();
|
|
if(ord >= order.size() || row >= VisitedRowsVectorSize(order[ord]))
|
|
return false;
|
|
|
|
// The module might have been edited in the meantime - so we have to extend this a bit.
|
|
if(ord >= m_visitedRows.size() || row >= m_visitedRows[ord].size())
|
|
{
|
|
Initialize(false);
|
|
// If it's still past the end of the vector, this means that ord >= order.GetLengthTailTrimmed(), i.e. we are trying to play an empty order.
|
|
if(ord >= m_visitedRows.size())
|
|
return false;
|
|
}
|
|
|
|
MPT_ASSERT(chnState.size() >= m_sndFile.GetNumChannels());
|
|
LoopState newState{chnState.first(m_sndFile.GetNumChannels()), ignoreRow};
|
|
const auto rowLoopState = m_visitedLoopStates.find({ord, row});
|
|
const bool oldHadLoops = (rowLoopState != m_visitedLoopStates.end() && !rowLoopState->second.empty());
|
|
const bool newHasLoops = newState.HasLoops();
|
|
const bool wasVisited = m_visitedRows[ord][row];
|
|
|
|
// Check if new state is part of row state already. If so, we visited this row already and thus the module must be looping
|
|
if(!oldHadLoops && !newHasLoops && wasVisited)
|
|
return true;
|
|
if(oldHadLoops && mpt::contains(rowLoopState->second, newState))
|
|
return true;
|
|
|
|
if(newHasLoops)
|
|
m_rowsSpentInLoops++;
|
|
|
|
if(oldHadLoops || newHasLoops)
|
|
{
|
|
// Convert to set representation if it isn't already
|
|
if(!oldHadLoops && wasVisited)
|
|
m_visitedLoopStates[{ord, row}].emplace_back();
|
|
m_visitedLoopStates[{ord, row}].emplace_back(std::move(newState));
|
|
}
|
|
m_visitedRows[ord][row] = true;
|
|
return false;
|
|
}
|
|
|
|
|
|
// Get the needed vector size for a given pattern.
|
|
ROWINDEX RowVisitor::VisitedRowsVectorSize(PATTERNINDEX pattern) const noexcept
|
|
{
|
|
if(m_sndFile.Patterns.IsValidPat(pattern))
|
|
return m_sndFile.Patterns[pattern].GetNumRows();
|
|
else
|
|
return 1; // Non-existing patterns consist of a "fake" row.
|
|
}
|
|
|
|
|
|
// Find the first row that has not been played yet.
|
|
// The order and row is stored in the order and row variables on success, on failure they contain invalid values.
|
|
// If onlyUnplayedPatterns is true (default), only completely unplayed patterns are considered, otherwise a song can start on any unplayed row.
|
|
// Function returns true on success.
|
|
bool RowVisitor::GetFirstUnvisitedRow(ORDERINDEX &ord, ROWINDEX &row, bool onlyUnplayedPatterns) const
|
|
{
|
|
const auto &order = Order();
|
|
const ORDERINDEX endOrder = order.GetLengthTailTrimmed();
|
|
for(ord = 0; ord < endOrder; ord++)
|
|
{
|
|
if(!order.IsValidPat(ord))
|
|
continue;
|
|
|
|
if(ord >= m_visitedRows.size())
|
|
{
|
|
// Not yet initialized => unvisited
|
|
row = 0;
|
|
return true;
|
|
}
|
|
|
|
const auto &visitedRows = m_visitedRows[ord];
|
|
const auto firstUnplayedRow = std::find(visitedRows.begin(), visitedRows.end(), onlyUnplayedPatterns);
|
|
if(onlyUnplayedPatterns && firstUnplayedRow == visitedRows.end())
|
|
{
|
|
// No row of this pattern has been played yet.
|
|
row = 0;
|
|
return true;
|
|
} else if(!onlyUnplayedPatterns)
|
|
{
|
|
// Return the first unplayed row in this pattern
|
|
if(firstUnplayedRow != visitedRows.end())
|
|
{
|
|
row = static_cast<ROWINDEX>(std::distance(visitedRows.begin(), firstUnplayedRow));
|
|
return true;
|
|
}
|
|
if(visitedRows.size() < m_sndFile.Patterns[order[ord]].GetNumRows())
|
|
{
|
|
// History is not fully initialized
|
|
row = static_cast<ROWINDEX>(visitedRows.size());
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Didn't find anything :(
|
|
ord = ORDERINDEX_INVALID;
|
|
row = ROWINDEX_INVALID;
|
|
return false;
|
|
}
|
|
|
|
|
|
OPENMPT_NAMESPACE_END
|