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Henrik RydgårdandClaude Opus 5.5
ca72577702
A rewind used up the state it restored, so rewinding, playing on a bit and rewinding again went further back than the state you just came from. Now the state stays, and only a rewind within 0.8 seconds of the last one steps back past it. "Seconds ago" was wall-clock time since the snapshot, which counted pauses, fast-forward and time spent in states rewound to earlier. It's now emulated time from where the rewinding started. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
98 lines
2.9 KiB
C++
98 lines
2.9 KiB
C++
#pragma once
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#include <mutex>
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#include <thread>
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#include "Common/Serialize/Serializer.h"
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#include "Common/CommonTypes.h"
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#include "Common/TimeUtil.h"
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namespace SaveState {
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// This ring buffer of states is for rewind save states, which are kept in RAM.
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// Save states are compressed against one of two reference saves (bases_), and the reference
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// is switched to a fresh save every N saves, where N is BASE_USAGE_INTERVAL.
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// The compression is a simple block based scheme where 0 means to copy a block from the base,
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// and 1 means that the following bytes are the next block. See Compress/LockedDecompress.
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class StateRingbuffer {
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public:
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StateRingbuffer() {
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size_ = REWIND_NUM_STATES;
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states_.resize(size_);
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baseMapping_.resize(size_);
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}
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~StateRingbuffer() {
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if (compressThread_.joinable()) {
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compressThread_.join();
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}
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}
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CChunkFileReader::Error Save();
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CChunkFileReader::Error Restore(std::string *errorString, std::string *metadata);
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void ScheduleCompress(std::vector<u8> *result, const std::vector<u8> *state, const std::vector<u8> *base);
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void Compress(std::vector<u8> &result, const std::vector<u8> &state, const std::vector<u8> &base);
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void LockedDecompress(std::vector<u8> &result, const std::vector<u8> &compressed, const std::vector<u8> &base);
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void Clear();
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bool Empty() const {
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return count_ == 0;
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}
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void Process();
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void NotifyState();
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double NextStateTimestamp() const;
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private:
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bool BaseAlive(int generation) const;
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void DropNewest();
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const int BLOCK_SIZE = 8192;
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const int REWIND_NUM_STATES = 20;
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// TODO: Instead, based on size of compressed state?
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const int BASE_USAGE_INTERVAL = 15;
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// A rewind this soon after the last one steps back past the state that one restored.
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const double STEP_BACK_SECONDS = 0.8;
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typedef std::vector<u8> StateBuffer;
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struct RewindState {
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StateBuffer stateBuffer;
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// CoreTiming's clock when the state was taken, in seconds.
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double emuTime = 0.0;
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bool empty() const { return stateBuffer.empty(); }
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void clear() { stateBuffer.clear(); emuTime = 0.0; }
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};
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// The slot the next save goes in, and how many slots before it hold states we can restore.
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int next_ = 0;
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int count_ = 0;
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int size_;
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std::vector<RewindState> states_;
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StateBuffer bases_[2];
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// Which generation each base slot currently holds, and which generation each state was
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// compressed against. There are more states than bases, so states do go stale.
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int baseGeneration_[2] = {-1, -1};
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int nextBaseGeneration_ = 0;
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std::vector<int> baseMapping_;
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std::mutex lock_;
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std::thread compressThread_;
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std::vector<u8> buffer_;
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int base_ = -1;
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int baseUsage_ = 0;
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double rewindLastTime_ = 0.0f;
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// Whether the newest state is the one the last rewind restored, and when that was.
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bool newestRestored_ = false;
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double lastRestoreTime_ = 0.0;
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// CoreTiming's clock when the current run of rewinds started, for "seconds ago".
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double rewindFromEmuTime_ = 0.0;
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bool retryingAfterFailure_ = false;
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};
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} // namespace SaveState
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