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TSR Berry 2023-04-08 01:22:00 +02:00 • committed by Mary
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113
src/Ryujinx.Graphics.Gpu/Shader/HashTable/HashState.cs Normal file
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using System;
using System.Runtime.InteropServices;
namespace Ryujinx.Graphics.Gpu.Shader.HashTable
{
/// <summary>
/// State of a hash calculation.
/// </summary>
struct HashState
{
// This is using a slightly modified implementation of FastHash64.
// Reference: https://github.com/ztanml/fast-hash/blob/master/fasthash.c
private const ulong M = 0x880355f21e6d1965UL;
private ulong _hash;
private int _start;
/// <summary>
/// One shot hash calculation for a given data.
/// </summary>
/// <param name="data">Data to be hashed</param>
/// <returns>Hash of the given data</returns>
public static uint CalcHash(ReadOnlySpan<byte> data)
{
HashState state = new HashState();
state.Initialize();
state.Continue(data);
return state.Finalize(data);
}
/// <summary>
/// Initializes the hash state.
/// </summary>
public void Initialize()
{
_hash = 23;
}
/// <summary>
/// Calculates the hash of the given data.
/// </summary>
/// <remarks>
/// The full data must be passed on <paramref name="data"/>.
/// If this is not the first time the method is called, then <paramref name="data"/> must start with the data passed on the last call.
/// If a smaller slice of the data was already hashed before, only the additional data will be hashed.
/// This can be used for additive hashing of data in chuncks.
/// </remarks>
/// <param name="data">Data to be hashed</param>
public void Continue(ReadOnlySpan<byte> data)
{
ulong h = _hash;
ReadOnlySpan<ulong> dataAsUlong = MemoryMarshal.Cast<byte, ulong>(data.Slice(_start));
for (int i = 0; i < dataAsUlong.Length; i++)
{
ulong value = dataAsUlong[i];
h ^= Mix(value);
h *= M;
}
_hash = h;
_start = data.Length & ~7;
}
/// <summary>
/// Performs the hash finalization step, and returns the calculated hash.
/// </summary>
/// <remarks>
/// The full data must be passed on <paramref name="data"/>.
/// <paramref name="data"/> must start with the data passed on the last call to <see cref="Continue"/>.
/// No internal state is changed, so one can still continue hashing data with <see cref="Continue"/>
/// after calling this method.
/// </remarks>
/// <param name="data">Data to be hashed</param>
/// <returns>Hash of all the data hashed with this <see cref="HashState"/></returns>
public uint Finalize(ReadOnlySpan<byte> data)
{
ulong h = _hash;
int remainder = data.Length & 7;
if (remainder != 0)
{
ulong v = 0;
for (int i = data.Length - remainder; i < data.Length; i++)
{
v |= (ulong)data[i] << ((i - remainder) * 8);
}
h ^= Mix(v);
h *= M;
}
h = Mix(h);
return (uint)(h - (h >> 32));
}
/// <summary>
/// Hash mix function.
/// </summary>
/// <param name="h">Hash to mix</param>
/// <returns>Mixed hash</returns>
private static ulong Mix(ulong h)
{
h ^= h >> 23;
h *= 0x2127599bf4325c37UL;
h ^= h >> 47;
return h;
}
}
}

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src/Ryujinx.Graphics.Gpu/Shader/HashTable/IDataAccessor.cs Normal file
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using System;
namespace Ryujinx.Graphics.Gpu.Shader.HashTable
{
/// <summary>
/// Data accessor, used by <see cref="PartitionedHashTable{T}"/> to access data of unknown length.
/// </summary>
/// <remarks>
/// This will be used to access chuncks of data and try finding a match on the table.
/// This is necessary because the data size is assumed to be unknown, and so the
/// hash table must try to "guess" the size of the data based on the entries on the table.
/// </remarks>
public interface IDataAccessor
{
/// <summary>
/// Gets a span of shader code at the specified offset, with at most the specified size.
/// </summary>
/// <remarks>
/// This might return a span smaller than the requested <paramref name="length"/> if there's
/// no more code available.
/// </remarks>
/// <param name="offset">Offset in shader code</param>
/// <param name="length">Size in bytes</param>
/// <returns>Shader code span</returns>
ReadOnlySpan<byte> GetSpan(int offset, int length);
}
}

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src/Ryujinx.Graphics.Gpu/Shader/HashTable/PartitionHashTable.cs Normal file
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using System;
using System.Collections.Generic;
using System.Numerics;
namespace Ryujinx.Graphics.Gpu.Shader.HashTable
{
/// <summary>
/// Partitioned hash table.
/// </summary>
/// <typeparam name="T">Hash table entry type</typeparam>
class PartitionHashTable<T>
{
/// <summary>
/// Hash table entry.
/// </summary>
private struct Entry
{
/// <summary>
/// Hash <see cref="OwnSize"/> bytes of <see cref="Data"/>.
/// </summary>
public readonly uint Hash;
/// <summary>
/// If this entry is only a sub-region of <see cref="Data"/>, this indicates the size in bytes
/// of that region. Otherwise, it should be zero.
/// </summary>
public readonly int OwnSize;
/// <summary>
/// Data used to compute the hash for this entry.
/// </summary>
/// <remarks>
/// To avoid additional allocations, this might be a instance of the full entry data,
/// and only a sub-region of it might be actually used by this entry. Such sub-region
/// has its size indicated by <see cref="OwnSize"/> in this case.
/// </remarks>
public readonly byte[] Data;
/// <summary>
/// Item associated with this entry.
/// </summary>
public T Item;
/// <summary>
/// Indicates if the entry is partial, which means that this entry is only for a sub-region of the data.
/// </summary>
/// <remarks>
/// Partial entries have no items associated with them. They just indicates that the data might be present on
/// the table, and one must keep looking for the full entry on other tables of larger data size.
/// </remarks>
public bool IsPartial => OwnSize != 0;
/// <summary>
/// Creates a new partial hash table entry.
/// </summary>
/// <param name="hash">Hash of the data</param>
/// <param name="ownerData">Full data</param>
/// <param name="ownSize">Size of the sub-region of data that belongs to this entry</param>
public Entry(uint hash, byte[] ownerData, int ownSize)
{
Hash = hash;
OwnSize = ownSize;
Data = ownerData;
Item = default;
}
/// <summary>
/// Creates a new full hash table entry.
/// </summary>
/// <param name="hash">Hash of the data</param>
/// <param name="data">Data</param>
/// <param name="item">Item associated with this entry</param>
public Entry(uint hash, byte[] data, T item)
{
Hash = hash;
OwnSize = 0;
Data = data;
Item = item;
}
/// <summary>
/// Gets the data for this entry, either full or partial.
/// </summary>
/// <returns>Data sub-region</returns>
public ReadOnlySpan<byte> GetData()
{
if (OwnSize != 0)
{
return new ReadOnlySpan<byte>(Data).Slice(0, OwnSize);
}
return Data;
}
}
/// <summary>
/// Hash table bucket.
/// </summary>
private struct Bucket
{
/// <summary>
/// Inline entry, to avoid allocations for the common single entry case.
/// </summary>
public Entry InlineEntry;
/// <summary>
/// List of additional entries for the not-so-common multiple entries case.
/// </summary>
public List<Entry> MoreEntries;
}
private Bucket[] _buckets;
private int _count;
/// <summary>
/// Total amount of entries on the hash table.
/// </summary>
public int Count => _count;
/// <summary>
/// Creates a new instance of the partitioned hash table.
/// </summary>
public PartitionHashTable()
{
_buckets = Array.Empty<Bucket>();
}
/// <summary>
/// Gets an item on the table, or adds a new one if not present.
/// </summary>
/// <param name="data">Data</param>
/// <param name="dataHash">Hash of the data</param>
/// <param name="item">Item to be added if not found</param>
/// <returns>Existing item if found, or <paramref name="item"/> if not found</returns>
public T GetOrAdd(byte[] data, uint dataHash, T item)
{
if (TryFindItem(dataHash, data, out T existingItem))
{
return existingItem;
}
Entry entry = new Entry(dataHash, data, item);
AddToBucket(dataHash, ref entry);
return item;
}
/// <summary>
/// Adds an item to the hash table.
/// </summary>
/// <param name="data">Data</param>
/// <param name="dataHash">Hash of the data</param>
/// <param name="item">Item to be added</param>
/// <returns>True if the item was added, false due to an item associated with the data already being on the table</returns>
public bool Add(byte[] data, uint dataHash, T item)
{
if (TryFindItem(dataHash, data, out _))
{
return false;
}
Entry entry = new Entry(dataHash, data, item);
AddToBucket(dataHash, ref entry);
return true;
}
/// <summary>
/// Adds a partial entry to the hash table.
/// </summary>
/// <param name="ownerData">Full data</param>
/// <param name="ownSize">Size of the sub-region of <paramref name="ownerData"/> used by the partial entry</param>
/// <returns>True if added, false otherwise</returns>
public bool AddPartial(byte[] ownerData, int ownSize)
{
ReadOnlySpan<byte> data = new ReadOnlySpan<byte>(ownerData).Slice(0, ownSize);
return AddPartial(ownerData, HashState.CalcHash(data), ownSize);
}
/// <summary>
/// Adds a partial entry to the hash table.
/// </summary>
/// <param name="ownerData">Full data</param>
/// <param name="dataHash">Hash of the data sub-region</param>
/// <param name="ownSize">Size of the sub-region of <paramref name="ownerData"/> used by the partial entry</param>
/// <returns>True if added, false otherwise</returns>
public bool AddPartial(byte[] ownerData, uint dataHash, int ownSize)
{
ReadOnlySpan<byte> data = new ReadOnlySpan<byte>(ownerData).Slice(0, ownSize);
if (TryFindItem(dataHash, data, out _))
{
return false;
}
Entry entry = new Entry(dataHash, ownerData, ownSize);
AddToBucket(dataHash, ref entry);
return true;
}
/// <summary>
/// Adds entry with a given hash to the table.
/// </summary>
/// <param name="dataHash">Hash of the entry</param>
/// <param name="entry">Entry</param>
private void AddToBucket(uint dataHash, ref Entry entry)
{
int pow2Count = GetPow2Count(++_count);
if (pow2Count != _buckets.Length)
{
Rebuild(pow2Count);
}
ref Bucket bucket = ref GetBucketForHash(dataHash);
AddToBucket(ref bucket, ref entry);
}
/// <summary>
/// Adds an entry to a bucket.
/// </summary>
/// <param name="bucket">Bucket to add the entry into</param>
/// <param name="entry">Entry to be added</param>
private void AddToBucket(ref Bucket bucket, ref Entry entry)
{
if (bucket.InlineEntry.Data == null)
{
bucket.InlineEntry = entry;
}
else
{
(bucket.MoreEntries ??= new List<Entry>()).Add(entry);
}
}
/// <summary>
/// Creates partial entries on a new hash table for all existing full entries.
/// </summary>
/// <remarks>
/// This should be called every time a new hash table is created, and there are hash
/// tables with data sizes that are higher than that of the new table.
/// This will then fill the new hash table with "partial" entries of full entries
/// on the hash tables with higher size.
/// </remarks>
/// <param name="newTable">New hash table</param>
/// <param name="newEntrySize">Size of the data on the new hash table</param>
public void FillPartials(PartitionHashTable<T> newTable, int newEntrySize)
{
for (int i = 0; i < _buckets.Length; i++)
{
ref Bucket bucket = ref _buckets[i];
ref Entry inlineEntry = ref bucket.InlineEntry;
if (inlineEntry.Data != null)
{
if (!inlineEntry.IsPartial)
{
newTable.AddPartial(inlineEntry.Data, newEntrySize);
}
if (bucket.MoreEntries != null)
{
foreach (Entry entry in bucket.MoreEntries)
{
if (entry.IsPartial)
{
continue;
}
newTable.AddPartial(entry.Data, newEntrySize);
}
}
}
}
}
/// <summary>
/// Tries to find an item on the table.
/// </summary>
/// <param name="dataHash">Hash of <paramref name="data"/></param>
/// <param name="data">Data to find</param>
/// <param name="item">Item associated with the data</param>
/// <returns>True if an item was found, false otherwise</returns>
private bool TryFindItem(uint dataHash, ReadOnlySpan<byte> data, out T item)
{
if (_count == 0)
{
item = default;
return false;
}
ref Bucket bucket = ref GetBucketForHash(dataHash);
if (bucket.InlineEntry.Data != null)
{
if (bucket.InlineEntry.Hash == dataHash && bucket.InlineEntry.GetData().SequenceEqual(data))
{
item = bucket.InlineEntry.Item;
return true;
}
if (bucket.MoreEntries != null)
{
foreach (Entry entry in bucket.MoreEntries)
{
if (entry.Hash == dataHash && entry.GetData().SequenceEqual(data))
{
item = entry.Item;
return true;
}
}
}
}
item = default;
return false;
}
/// <summary>
/// Indicates the result of a hash table lookup.
/// </summary>
public enum SearchResult
{
/// <summary>
/// No entry was found, the search must continue on hash tables of lower size.
/// </summary>
NotFound,
/// <summary>
/// A partial entry was found, the search must continue on hash tables of higher size.
/// </summary>
FoundPartial,
/// <summary>
/// A full entry was found, the search was concluded and the item can be retrieved.
/// </summary>
FoundFull
}
/// <summary>
/// Tries to find an item on the table.
/// </summary>
/// <param name="dataAccessor">Data accessor</param>
/// <param name="size">Size of the hash table data</param>
/// <param name="item">The item on the table, if found, otherwise unmodified</param>
/// <param name="data">The data on the table, if found, otherwise unmodified</param>
/// <returns>Table lookup result</returns>
public SearchResult TryFindItem(scoped ref SmartDataAccessor dataAccessor, int size, scoped ref T item, scoped ref byte[] data)
{
if (_count == 0)
{
return SearchResult.NotFound;
}
ReadOnlySpan<byte> dataSpan = dataAccessor.GetSpanAndHash(size, out uint dataHash);
if (dataSpan.Length != size)
{
return SearchResult.NotFound;
}
ref Bucket bucket = ref GetBucketForHash(dataHash);
if (bucket.InlineEntry.Data != null)
{
if (bucket.InlineEntry.Hash == dataHash && bucket.InlineEntry.GetData().SequenceEqual(dataSpan))
{
item = bucket.InlineEntry.Item;
data = bucket.InlineEntry.Data;
return bucket.InlineEntry.IsPartial ? SearchResult.FoundPartial : SearchResult.FoundFull;
}
if (bucket.MoreEntries != null)
{
foreach (Entry entry in bucket.MoreEntries)
{
if (entry.Hash == dataHash && entry.GetData().SequenceEqual(dataSpan))
{
item = entry.Item;
data = entry.Data;
return entry.IsPartial ? SearchResult.FoundPartial : SearchResult.FoundFull;
}
}
}
}
return SearchResult.NotFound;
}
/// <summary>
/// Rebuilds the table for a new count.
/// </summary>
/// <param name="newPow2Count">New power of two count of the table</param>
private void Rebuild(int newPow2Count)
{
Bucket[] newBuckets = new Bucket[newPow2Count];
uint mask = (uint)newPow2Count - 1;
for (int i = 0; i < _buckets.Length; i++)
{
ref Bucket bucket = ref _buckets[i];
if (bucket.InlineEntry.Data != null)
{
AddToBucket(ref newBuckets[(int)(bucket.InlineEntry.Hash & mask)], ref bucket.InlineEntry);
if (bucket.MoreEntries != null)
{
foreach (Entry entry in bucket.MoreEntries)
{
Entry entryCopy = entry;
AddToBucket(ref newBuckets[(int)(entry.Hash & mask)], ref entryCopy);
}
}
}
}
_buckets = newBuckets;
}
/// <summary>
/// Gets the bucket for a given hash.
/// </summary>
/// <param name="hash">Data hash</param>
/// <returns>Bucket for the hash</returns>
private ref Bucket GetBucketForHash(uint hash)
{
int index = (int)(hash & (_buckets.Length - 1));
return ref _buckets[index];
}
/// <summary>
/// Gets a power of two count from a regular count.
/// </summary>
/// <param name="count">Count</param>
/// <returns>Power of two count</returns>
private static int GetPow2Count(int count)
{
// This returns the nearest power of two that is lower than count.
// This was done to optimize memory usage rather than performance.
return 1 << BitOperations.Log2((uint)count);
}
}
}

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src/Ryujinx.Graphics.Gpu/Shader/HashTable/PartitionedHashTable.cs Normal file
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using System;
using System.Collections.Generic;
using System.Diagnostics;
namespace Ryujinx.Graphics.Gpu.Shader.HashTable
{
/// <summary>
/// Partitioned hash table.
/// </summary>
/// <typeparam name="T"></typeparam>
public class PartitionedHashTable<T>
{
/// <summary>
/// Entry for a given data size.
/// </summary>
private readonly struct SizeEntry
{
/// <summary>
/// Size for the data that will be stored on the hash table on this entry.
/// </summary>
public int Size { get; }
/// <summary>
/// Number of entries on the hash table.
/// </summary>
public int TableCount => _table.Count;
private readonly PartitionHashTable<T> _table;
/// <summary>
/// Creates an entry for a given size.
/// </summary>
/// <param name="size">Size of the data to be stored on this entry</param>
public SizeEntry(int size)
{
Size = size;
_table = new PartitionHashTable<T>();
}
/// <summary>
/// Gets an item for existing data, or adds a new one.
/// </summary>
/// <param name="data">Data associated with the item</param>
/// <param name="dataHash">Hash of <paramref name="data"/></param>
/// <param name="item">Item to be added</param>
/// <returns>Existing item, or <paramref name="item"/> if not present</returns>
public T GetOrAdd(byte[] data, uint dataHash, T item)
{
Debug.Assert(data.Length == Size);
return _table.GetOrAdd(data, dataHash, item);
}
/// <summary>
/// Adds a new item.
/// </summary>
/// <param name="data">Data associated with the item</param>
/// <param name="dataHash">Hash of <paramref name="data"/></param>
/// <param name="item">Item to be added</param>
/// <returns>True if added, false otherwise</returns>
public bool Add(byte[] data, uint dataHash, T item)
{
Debug.Assert(data.Length == Size);
return _table.Add(data, dataHash, item);
}
/// <summary>
/// Adds a partial entry.
/// </summary>
/// <param name="ownerData">Full entry data</param>
/// <param name="dataHash">Hash of the sub-region of the data that belongs to this entry</param>
/// <returns>True if added, false otherwise</returns>
public bool AddPartial(byte[] ownerData, uint dataHash)
{
return _table.AddPartial(ownerData, dataHash, Size);
}
/// <summary>
/// Fills a new hash table with "partials" of existing full entries of higher size.
/// </summary>
/// <param name="newEntry">Entry with the new hash table</param>
public void FillPartials(SizeEntry newEntry)
{
Debug.Assert(newEntry.Size < Size);
_table.FillPartials(newEntry._table, newEntry.Size);
}
/// <summary>
/// Tries to find an item on the hash table.
/// </summary>
/// <param name="dataAccessor">Data accessor</param>
/// <param name="item">The item on the table, if found, otherwise unmodified</param>
/// <param name="data">The data on the table, if found, otherwise unmodified</param>
/// <returns>Table lookup result</returns>
public PartitionHashTable<T>.SearchResult TryFindItem(scoped ref SmartDataAccessor dataAccessor, scoped ref T item, scoped ref byte[] data)
{
return _table.TryFindItem(ref dataAccessor, Size, ref item, ref data);
}
}
private readonly List<SizeEntry> _sizeTable;
/// <summary>
/// Creates a new partitioned hash table.
/// </summary>
public PartitionedHashTable()
{
_sizeTable = new List<SizeEntry>();
}
/// <summary>
/// Adds a new item to the table.
/// </summary>
/// <param name="data">Data</param>
/// <param name="item">Item associated with the data</param>
public void Add(byte[] data, T item)
{
GetOrAdd(data, item);
}
/// <summary>
/// Gets an existing item from the table, or adds a new one if not present.
/// </summary>
/// <param name="data">Data</param>
/// <param name="item">Item associated with the data</param>
/// <returns>Existing item, or <paramref name="item"/> if not present</returns>
public T GetOrAdd(byte[] data, T item)
{
SizeEntry sizeEntry;
int index = BinarySearch(_sizeTable, data.Length);
if (index < _sizeTable.Count && _sizeTable[index].Size == data.Length)
{
sizeEntry = _sizeTable[index];
}
else
{
if (index < _sizeTable.Count && _sizeTable[index].Size < data.Length)
{
index++;
}
sizeEntry = new SizeEntry(data.Length);
_sizeTable.Insert(index, sizeEntry);
for (int i = index + 1; i < _sizeTable.Count; i++)
{
_sizeTable[i].FillPartials(sizeEntry);
}
}
HashState hashState = new HashState();
hashState.Initialize();
for (int i = 0; i < index; i++)
{
ReadOnlySpan<byte> dataSlice = new ReadOnlySpan<byte>(data).Slice(0, _sizeTable[i].Size);
hashState.Continue(dataSlice);
_sizeTable[i].AddPartial(data, hashState.Finalize(dataSlice));
}
hashState.Continue(data);
return sizeEntry.GetOrAdd(data, hashState.Finalize(data), item);
}
/// <summary>
/// Performs binary search on a list of hash tables, each one with a fixed data size.
/// </summary>
/// <param name="entries">List of hash tables</param>
/// <param name="size">Size to search for</param>
/// <returns>Index of the hash table with the given size, or nearest one otherwise</returns>
private static int BinarySearch(List<SizeEntry> entries, int size)
{
int left = 0;
int middle = 0;
int right = entries.Count - 1;
while (left <= right)
{
middle = left + ((right - left) >> 1);
SizeEntry entry = entries[middle];
if (size == entry.Size)
{
break;
}
if (size < entry.Size)
{
right = middle - 1;
}
else
{
left = middle + 1;
}
}
return middle;
}
/// <summary>
/// Tries to find an item on the table.
/// </summary>
/// <param name="dataAccessor">Data accessor</param>
/// <param name="item">Item, if found</param>
/// <param name="data">Data, if found</param>
/// <returns>True if the item was found on the table, false otherwise</returns>
public bool TryFindItem(IDataAccessor dataAccessor, out T item, out byte[] data)
{
SmartDataAccessor sda = new SmartDataAccessor(dataAccessor);
item = default;
data = null;
int left = 0;
int right = _sizeTable.Count;
while (left != right)
{
int index = left + ((right - left) >> 1);
PartitionHashTable<T>.SearchResult result = _sizeTable[index].TryFindItem(ref sda, ref item, ref data);
if (result == PartitionHashTable<T>.SearchResult.FoundFull)
{
return true;
}
if (result == PartitionHashTable<T>.SearchResult.NotFound)
{
right = index;
}
else /* if (result == PartitionHashTable<T>.SearchResult.FoundPartial) */
{
left = index + 1;
}
}
data = null;
return false;
}
}
}

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src/Ryujinx.Graphics.Gpu/Shader/HashTable/SmartDataAccessor.cs Normal file
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using System;
using System.Collections.Generic;
namespace Ryujinx.Graphics.Gpu.Shader.HashTable
{
/// <summary>
/// Smart data accessor that can cache data and hashes to avoid reading and re-hashing the same memory regions.
/// </summary>
ref struct SmartDataAccessor
{
private readonly IDataAccessor _dataAccessor;
private ReadOnlySpan<byte> _data;
private readonly SortedList<int, HashState> _cachedHashes;
/// <summary>
/// Creates a new smart data accessor.
/// </summary>
/// <param name="dataAccessor">Data accessor</param>
public SmartDataAccessor(IDataAccessor dataAccessor)
{
_dataAccessor = dataAccessor;
_data = ReadOnlySpan<byte>.Empty;
_cachedHashes = new SortedList<int, HashState>();
}
/// <summary>
/// Get a spans of a given size.
/// </summary>
/// <remarks>
/// The actual length of the span returned depends on the <see cref="IDataAccessor"/>
/// and might be less than requested.
/// </remarks>
/// <param name="length">Size in bytes</param>
/// <returns>Span with the requested size</returns>
public ReadOnlySpan<byte> GetSpan(int length)
{
if (_data.Length < length)
{
_data = _dataAccessor.GetSpan(0, length);
}
else if (_data.Length > length)
{
return _data.Slice(0, length);
}
return _data;
}
/// <summary>
/// Gets a span of the requested size, and a hash of its data.
/// </summary>
/// <param name="length">Length of the span</param>
/// <param name="hash">Hash of the span data</param>
/// <returns>Span of data</returns>
public ReadOnlySpan<byte> GetSpanAndHash(int length, out uint hash)
{
ReadOnlySpan<byte> data = GetSpan(length);
hash = data.Length == length ? CalcHashCached(data) : 0;
return data;
}
/// <summary>
/// Calculates the hash for a requested span.
/// This will try to use a cached hash if the data was already accessed before, to avoid re-hashing.
/// </summary>
/// <param name="data">Data to be hashed</param>
/// <returns>Hash of the data</returns>
private uint CalcHashCached(ReadOnlySpan<byte> data)
{
HashState state = default;
bool found = false;
for (int i = _cachedHashes.Count - 1; i >= 0; i--)
{
int cachedHashSize = _cachedHashes.Keys[i];
if (cachedHashSize < data.Length)
{
state = _cachedHashes.Values[i];
found = true;
break;
}
}
if (!found)
{
state = new HashState();
state.Initialize();
}
state.Continue(data);
_cachedHashes[data.Length & ~7] = state;
return state.Finalize(data);
}
}
}