Archived
Step 4 - 二级页表 + 缺页 + FIFO
This commit is contained in:
@@ -0,0 +1,74 @@
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using System;
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namespace VMdemo.Simulation
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{
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public readonly struct MemoryAccessResult
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{
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public MemoryAccessResult(ulong pfn, bool pageTableHit, bool pageFault, EvictionInfo eviction)
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{
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Pfn = pfn;
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PageTableHit = pageTableHit;
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PageFault = pageFault;
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Eviction = eviction;
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}
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public ulong Pfn { get; }
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public bool PageTableHit { get; }
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public bool PageFault { get; }
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public EvictionInfo Eviction { get; }
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}
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public static class MemoryAccessResolver
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{
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public static MemoryAccessResult Resolve(
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ulong vpn,
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ulong l1Index,
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ulong l2Index,
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TwoLevelPageTable pageTable,
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PhysicalMemoryManager physicalMemoryManager,
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TlbCache tlbCache)
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{
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if (pageTable == null)
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{
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throw new ArgumentNullException(nameof(pageTable));
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}
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if (physicalMemoryManager == null)
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{
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throw new ArgumentNullException(nameof(physicalMemoryManager));
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}
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if (tlbCache == null)
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{
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throw new ArgumentNullException(nameof(tlbCache));
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}
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if (pageTable.TryGetPresentPfn(l1Index, l2Index, out var pfn))
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{
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tlbCache.InsertOrUpdate(vpn, pfn);
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return new MemoryAccessResult(pfn, true, false, EvictionInfo.None);
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}
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var allocation = physicalMemoryManager.AllocateForVpn(vpn);
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if (allocation.Eviction.HasEvicted)
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{
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pageTable.GetIndicesFromVpn(
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allocation.Eviction.EvictedVpn,
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out var evictedL1Index,
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out var evictedL2Index);
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pageTable.MarkNotPresent(evictedL1Index, evictedL2Index);
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tlbCache.Remove(allocation.Eviction.EvictedVpn);
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}
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pageTable.SetPresent(l1Index, l2Index, allocation.AssignedPfn);
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tlbCache.InsertOrUpdate(vpn, allocation.AssignedPfn);
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return new MemoryAccessResult(
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allocation.AssignedPfn,
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pageTableHit: false,
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pageFault: true,
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allocation.Eviction);
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}
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}
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}
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@@ -0,0 +1,11 @@
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fileFormatVersion: 2
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guid: 69a345783d80681488273b665f20247f
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MonoImporter:
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externalObjects: {}
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serializedVersion: 2
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defaultReferences: []
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executionOrder: 0
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icon: {instanceID: 0}
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userData:
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assetBundleName:
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assetBundleVariant:
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@@ -0,0 +1,36 @@
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using System;
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namespace VMdemo.Simulation
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{
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[Serializable]
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public readonly struct PageTableEntry
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{
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public PageTableEntry(ulong pfn, bool present, bool dirty = false)
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{
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Pfn = pfn;
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Present = present;
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Dirty = dirty;
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}
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public ulong Pfn { get; }
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public bool Present { get; }
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public bool Dirty { get; }
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public static PageTableEntry NotPresent => new PageTableEntry(0UL, false, false);
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public PageTableEntry MarkPresent(ulong pfn, bool dirty = false)
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{
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return new PageTableEntry(pfn, true, dirty);
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}
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public PageTableEntry MarkNotPresent()
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{
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return new PageTableEntry(Pfn, false, Dirty);
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}
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public override string ToString()
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{
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return $"PFN={Pfn}, Present={Present}, Dirty={Dirty}";
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}
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}
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}
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@@ -0,0 +1,11 @@
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fileFormatVersion: 2
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guid: 319e4b22dc36b754db1b833626fa2681
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MonoImporter:
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externalObjects: {}
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serializedVersion: 2
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defaultReferences: []
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executionOrder: 0
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icon: {instanceID: 0}
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userData:
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assetBundleName:
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assetBundleVariant:
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@@ -0,0 +1,133 @@
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using System;
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using System.Collections.Generic;
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namespace VMdemo.Simulation
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{
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public readonly struct EvictionInfo
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{
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public EvictionInfo(bool hasEvicted, ulong evictedVpn, ulong evictedPfn)
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{
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HasEvicted = hasEvicted;
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EvictedVpn = evictedVpn;
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EvictedPfn = evictedPfn;
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}
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public bool HasEvicted { get; }
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public ulong EvictedVpn { get; }
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public ulong EvictedPfn { get; }
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public static EvictionInfo None => new EvictionInfo(false, 0UL, 0UL);
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}
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public readonly struct AllocationResult
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{
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public AllocationResult(ulong assignedPfn, bool wasAlreadyResident, EvictionInfo eviction)
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{
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AssignedPfn = assignedPfn;
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WasAlreadyResident = wasAlreadyResident;
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Eviction = eviction;
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}
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public ulong AssignedPfn { get; }
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public bool WasAlreadyResident { get; }
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public EvictionInfo Eviction { get; }
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}
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public class PhysicalMemoryManager
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{
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private readonly Queue<ResidentPage> _fifoQueue = new Queue<ResidentPage>();
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private readonly Dictionary<ulong, ulong> _residentByVpn = new Dictionary<ulong, ulong>();
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private ulong _nextFreeFrame;
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public PhysicalMemoryManager(ulong frameCount)
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{
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if (frameCount < 1UL)
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{
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throw new ArgumentOutOfRangeException(nameof(frameCount), "frameCount 必须 >= 1。");
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}
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FrameCount = frameCount;
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_nextFreeFrame = 0UL;
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}
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public ulong FrameCount { get; }
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public int ResidentCount => _residentByVpn.Count;
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public bool TryGetResidentPfn(ulong vpn, out ulong pfn)
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{
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return _residentByVpn.TryGetValue(vpn, out pfn);
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}
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public AllocationResult AllocateForVpn(ulong vpn)
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{
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if (_residentByVpn.TryGetValue(vpn, out var existingPfn))
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{
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return new AllocationResult(existingPfn, true, EvictionInfo.None);
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}
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EvictionInfo evictionInfo;
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ulong assignedPfn;
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if (_nextFreeFrame < FrameCount)
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{
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assignedPfn = _nextFreeFrame;
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_nextFreeFrame++;
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evictionInfo = EvictionInfo.None;
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}
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else
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{
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if (_fifoQueue.Count == 0)
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{
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throw new InvalidOperationException("内存已满但 FIFO 队列为空，状态异常。");
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}
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var victim = _fifoQueue.Dequeue();
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if (!_residentByVpn.Remove(victim.Vpn))
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{
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throw new InvalidOperationException("FIFO 淘汰项未出现在驻留映射中，状态异常。");
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}
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assignedPfn = victim.Pfn;
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evictionInfo = new EvictionInfo(true, victim.Vpn, victim.Pfn);
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}
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_residentByVpn[vpn] = assignedPfn;
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_fifoQueue.Enqueue(new ResidentPage(vpn, assignedPfn));
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return new AllocationResult(assignedPfn, false, evictionInfo);
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}
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public IReadOnlyList<ulong> GetFifoVpnOrder()
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{
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var order = new List<ulong>(_fifoQueue.Count);
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foreach (var page in _fifoQueue)
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{
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order.Add(page.Vpn);
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}
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return order;
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}
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public string FormatFifoQueue()
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{
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var order = GetFifoVpnOrder();
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if (order.Count == 0)
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{
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return "FIFO=[]";
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}
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return $"FIFO=[{string.Join(",", order)}]";
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}
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private readonly struct ResidentPage
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{
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public ResidentPage(ulong vpn, ulong pfn)
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{
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Vpn = vpn;
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Pfn = pfn;
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}
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public ulong Vpn { get; }
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public ulong Pfn { get; }
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}
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}
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}
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@@ -0,0 +1,11 @@
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fileFormatVersion: 2
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guid: 442eea92195560643874961592e5317d
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MonoImporter:
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externalObjects: {}
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serializedVersion: 2
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defaultReferences: []
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executionOrder: 0
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icon: {instanceID: 0}
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userData:
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assetBundleName:
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assetBundleVariant:
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@@ -0,0 +1,163 @@
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using System;
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using System.Collections.Generic;
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namespace VMdemo.Simulation
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{
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public class TwoLevelPageTable
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{
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private readonly Dictionary<ulong, Dictionary<ulong, PageTableEntry>> _table;
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private readonly ulong _l1Mask;
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private readonly ulong _l2Mask;
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private readonly ulong _vpnMask;
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public TwoLevelPageTable(int l1Bits, int l2Bits)
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{
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if (l1Bits < 0 || l1Bits > 64)
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{
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throw new ArgumentOutOfRangeException(nameof(l1Bits), "l1Bits 必须在 0 到 64 之间。");
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}
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if (l2Bits < 0 || l2Bits > 64)
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{
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throw new ArgumentOutOfRangeException(nameof(l2Bits), "l2Bits 必须在 0 到 64 之间。");
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}
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if (l1Bits + l2Bits <= 0 || l1Bits + l2Bits > 64)
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{
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throw new ArgumentOutOfRangeException(nameof(l2Bits), "l1Bits + l2Bits 必须在 1 到 64 之间。");
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}
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L1Bits = l1Bits;
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L2Bits = l2Bits;
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_table = new Dictionary<ulong, Dictionary<ulong, PageTableEntry>>();
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_l1Mask = GetBitMask(l1Bits);
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_l2Mask = GetBitMask(l2Bits);
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_vpnMask = GetBitMask(l1Bits + l2Bits);
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}
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public int L1Bits { get; }
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public int L2Bits { get; }
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public bool TryGetPresentPfn(ulong l1Index, ulong l2Index, out ulong pfn)
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{
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ValidateIndices(l1Index, l2Index);
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if (!_table.TryGetValue(l1Index, out var l2Table))
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{
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pfn = 0UL;
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return false;
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}
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if (!l2Table.TryGetValue(l2Index, out var entry) || !entry.Present)
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{
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pfn = 0UL;
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return false;
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}
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pfn = entry.Pfn;
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return true;
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}
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public bool TryGetEntry(ulong l1Index, ulong l2Index, out PageTableEntry entry)
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{
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ValidateIndices(l1Index, l2Index);
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if (_table.TryGetValue(l1Index, out var l2Table) &&
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l2Table.TryGetValue(l2Index, out var value))
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{
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entry = value;
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return true;
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}
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entry = PageTableEntry.NotPresent;
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return false;
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}
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public void SetPresent(ulong l1Index, ulong l2Index, ulong pfn, bool dirty = false)
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{
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ValidateIndices(l1Index, l2Index);
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if (!_table.TryGetValue(l1Index, out var l2Table))
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{
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l2Table = new Dictionary<ulong, PageTableEntry>();
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_table[l1Index] = l2Table;
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}
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l2Table[l2Index] = new PageTableEntry(pfn, true, dirty);
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}
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public bool MarkNotPresent(ulong l1Index, ulong l2Index)
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{
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ValidateIndices(l1Index, l2Index);
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if (!_table.TryGetValue(l1Index, out var l2Table) ||
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!l2Table.TryGetValue(l2Index, out var entry))
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{
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return false;
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}
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if (!entry.Present)
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{
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return false;
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}
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l2Table[l2Index] = entry.MarkNotPresent();
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return true;
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}
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public void GetIndicesFromVpn(ulong vpn, out ulong l1Index, out ulong l2Index)
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{
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if (L1Bits + L2Bits < 64 && (vpn & ~_vpnMask) != 0UL)
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{
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throw new ArgumentOutOfRangeException(nameof(vpn), "vpn 超出页表可表示范围。");
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}
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l2Index = vpn & _l2Mask;
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l1Index = L2Bits >= 64 ? 0UL : vpn >> L2Bits;
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ValidateIndices(l1Index, l2Index);
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}
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private void ValidateIndices(ulong l1Index, ulong l2Index)
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{
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if (!IsWithinBits(l1Index, L1Bits, _l1Mask))
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{
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throw new ArgumentOutOfRangeException(nameof(l1Index), "l1Index 超出 L1 位宽范围。");
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}
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if (!IsWithinBits(l2Index, L2Bits, _l2Mask))
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{
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throw new ArgumentOutOfRangeException(nameof(l2Index), "l2Index 超出 L2 位宽范围。");
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}
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}
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private static bool IsWithinBits(ulong value, int bits, ulong mask)
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{
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if (bits == 64)
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{
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return true;
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}
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if (bits == 0)
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{
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return value == 0UL;
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}
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return (value & ~mask) == 0UL;
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}
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private static ulong GetBitMask(int bits)
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{
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if (bits <= 0)
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{
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return 0UL;
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}
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if (bits >= 64)
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{
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return ulong.MaxValue;
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}
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return (1UL << bits) - 1UL;
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}
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}
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}
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@@ -0,0 +1,11 @@
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fileFormatVersion: 2
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||||
guid: 2ee7fcf06ce017648a41c05cc07db305
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MonoImporter:
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externalObjects: {}
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||||
serializedVersion: 2
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||||
defaultReferences: []
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||||
executionOrder: 0
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||||
icon: {instanceID: 0}
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||||
userData:
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||||
assetBundleName:
|
||||
assetBundleVariant:
|
||||
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Block a user