362 lines
15 KiB
C#
362 lines
15 KiB
C#
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using System;
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using System.Diagnostics;
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using System.Runtime.InteropServices;
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using Unity.Burst;
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#if !NET_DOTS
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using Unity.Burst.Intrinsics;
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#endif
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using Unity.Collections.LowLevel.Unsafe;
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using Unity.Mathematics;
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namespace Unity.Collections
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{
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[BurstCompatible]
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public static partial class xxHash3
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{
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/// <summary>
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/// Type used to compute hash based on multiple data feed
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/// </summary>
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/// <remarks>
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/// Allow to feed the internal hashing accumulators with data through multiple calls to <see cref="Update"/>, then retrieving the final hash value using <see cref="DigestHash64"/> or <see cref="DigestHash128"/>.
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/// More info about how to use this class in its constructor.
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/// </remarks>
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[BurstCompatible]
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public struct StreamingState
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{
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#region Public API
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/// <summary>
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/// Create a StreamingState object, ready to be used with the streaming API
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/// </summary>
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/// <param name="isHash64">true if we are computing a 64bits hash value, false if we are computing a 128bits one</param>
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/// <param name="seed">A seed value to be used to compute the hash, default is 0</param>
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/// <remarks>
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/// Once the object is constructed, you can call the <see cref="Update"/> method as many times as you want to accumulate data to hash.
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/// When all the data has been sent, call <see cref="DigestHash64"/> or <see cref="DigestHash128"/> to retrieve the corresponding key, the <see cref="StreamingState"/>
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/// instance will then be reset, using the same hash key size and same Seed in order to be ready to be used again.
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/// </remarks>
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public StreamingState(bool isHash64, ulong seed=0)
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{
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State = default;
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Reset(isHash64, seed);
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}
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/// <summary>
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/// Reset the state of the streaming instance using the given seed value.
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/// </summary>
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/// <param name="isHash64"></param>
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/// <param name="seed">The seed value to alter the computed hash value from</param>
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/// <remarks> Call this method to start a new streaming session based on this instance</remarks>
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public unsafe void Reset(bool isHash64, ulong seed=0UL)
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{
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// Reset the whole buffer to 0
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var size = UnsafeUtility.SizeOf<StreamingStateData>();
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UnsafeUtility.MemClear(UnsafeUtility.AddressOf(ref State), size);
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// Set back the saved states
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State.IsHash64 = isHash64 ? 1 : 0;
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// Init the accumulator with the prime numbers
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var acc = Acc;
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acc[0] = PRIME32_3;
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acc[1] = PRIME64_1;
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acc[2] = PRIME64_2;
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acc[3] = PRIME64_3;
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acc[4] = PRIME64_4;
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acc[5] = PRIME32_2;
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acc[6] = PRIME64_5;
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acc[7] = PRIME32_1;
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State.Seed = seed;
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fixed (byte* secret = xxHashDefaultKey.kSecret)
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{
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if (seed != 0)
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{
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// Must encode the secret key if we're using a seed, we store it in the state object
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EncodeSecretKey(SecretKey, secret, seed);
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}
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else
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{
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// Otherwise just copy it
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UnsafeUtility.MemCpy(SecretKey, secret, SECRET_KEY_SIZE);
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}
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}
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}
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/// <summary>
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/// Add some data to be hashed
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/// </summary>
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/// <param name="input">The memory buffer, can't be null</param>
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/// <param name="length">The length of the data to accumulate, can be zero</param>
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/// <remarks>This API allows you to feed very small data to be hashed, avoiding you to accumulate them in a big buffer, then computing the hash value from.</remarks>
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public unsafe void Update(void* input, int length)
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{
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var bInput = (byte*) input;
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var bEnd = bInput + length;
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var isHash64 = State.IsHash64;
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var secret = SecretKey;
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State.TotalLength += length;
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if (State.BufferedSize + length <= INTERNAL_BUFFER_SIZE)
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{
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UnsafeUtility.MemCpy(Buffer + State.BufferedSize, bInput, length);
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State.BufferedSize += length;
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return;
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}
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if (State.BufferedSize != 0)
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{
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var loadSize = INTERNAL_BUFFER_SIZE - State.BufferedSize;
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UnsafeUtility.MemCpy(Buffer + State.BufferedSize, bInput, loadSize);
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bInput += loadSize;
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ConsumeStripes(Acc, ref State.NbStripesSoFar, Buffer, INTERNAL_BUFFER_STRIPES, secret, isHash64);
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State.BufferedSize = 0;
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}
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if (bInput + INTERNAL_BUFFER_SIZE < bEnd)
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{
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var limit = bEnd - INTERNAL_BUFFER_SIZE;
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do
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{
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ConsumeStripes(Acc, ref State.NbStripesSoFar, bInput, INTERNAL_BUFFER_STRIPES, secret, isHash64);
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bInput += INTERNAL_BUFFER_SIZE;
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} while (bInput < limit);
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UnsafeUtility.MemCpy(Buffer + INTERNAL_BUFFER_SIZE - STRIPE_LEN, bInput - STRIPE_LEN, STRIPE_LEN);
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}
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if (bInput < bEnd)
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{
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var newBufferedSize = bEnd - bInput;
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UnsafeUtility.MemCpy(Buffer, bInput, newBufferedSize);
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State.BufferedSize = (int) newBufferedSize;
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}
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}
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/// <summary>
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/// Add the contents of input struct to the hash.
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/// </summary>
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/// <typeparam name="T">The input type.</typeparam>
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/// <param name="input">The input struct that will be hashed</param>
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/// <remarks>This API allows you to feed very small data to be hashed, avoiding you to accumulate them in a big buffer, then computing the hash value from.</remarks>
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[BurstCompatible(GenericTypeArguments = new [] { typeof(int) })]
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public unsafe void Update<T>(in T input) where T : unmanaged
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{
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Update(UnsafeUtilityExtensions.AddressOf(input), UnsafeUtility.SizeOf<T>());
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}
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/// <summary>
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/// Compute the 128bits value based on all the data that have been accumulated
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/// </summary>
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/// <returns>The hash value</returns>
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public unsafe uint4 DigestHash128()
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{
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CheckKeySize(0);
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unchecked
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{
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var secret = SecretKey;
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uint4 hash;
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if (State.TotalLength > MIDSIZE_MAX)
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{
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var acc = stackalloc ulong[ACC_NB];
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DigestLong(acc, secret, 0);
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var low64 = MergeAcc(acc, secret + SECRET_MERGEACCS_START,
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(ulong) State.TotalLength * PRIME64_1);
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var high64 = MergeAcc(acc, secret + SECRET_LIMIT - SECRET_MERGEACCS_START,
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~((ulong) State.TotalLength * PRIME64_2));
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hash = ToUint4(low64, high64);
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}
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else
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{
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hash = Hash128(Buffer, State.TotalLength, State.Seed);
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}
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Reset(State.IsHash64==1, State.Seed);
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return hash;
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}
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}
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/// <summary>
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/// Compute the 64bits value based on all the data that have been accumulated
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/// </summary>
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/// <returns>The hash value</returns>
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public unsafe uint2 DigestHash64()
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{
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CheckKeySize(1);
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unchecked
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{
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var secret = SecretKey;
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uint2 hash;
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if (State.TotalLength > MIDSIZE_MAX)
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{
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var acc = stackalloc ulong[ACC_NB];
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DigestLong(acc, secret, 1);
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hash = ToUint2(MergeAcc(acc, secret + SECRET_MERGEACCS_START, (ulong) State.TotalLength * PRIME64_1));
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}
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else
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{
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hash = Hash64(Buffer, State.TotalLength, State.Seed);
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}
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Reset(State.IsHash64==1, State.Seed);
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return hash;
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}
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}
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#endregion
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#region Constants
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private static readonly int SECRET_LIMIT = SECRET_KEY_SIZE - STRIPE_LEN;
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private static readonly int NB_STRIPES_PER_BLOCK = SECRET_LIMIT / SECRET_CONSUME_RATE;
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private static readonly int INTERNAL_BUFFER_SIZE = 256;
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private static readonly int INTERNAL_BUFFER_STRIPES = INTERNAL_BUFFER_SIZE / STRIPE_LEN;
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#endregion
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#region Wrapper to internal data storage
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unsafe ulong* Acc
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{
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[DebuggerStepThrough]
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get => (ulong*) UnsafeUtility.AddressOf(ref State.Acc);
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}
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unsafe byte* Buffer
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{
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[DebuggerStepThrough]
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get => (byte*) UnsafeUtility.AddressOf(ref State.Buffer);
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}
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unsafe byte* SecretKey
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{
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[DebuggerStepThrough]
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get => (byte*) UnsafeUtility.AddressOf(ref State.SecretKey);
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}
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#endregion
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#region Data storage
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private StreamingStateData State;
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[StructLayout(LayoutKind.Explicit)]
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struct StreamingStateData
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{
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[FieldOffset(0)] public ulong Acc; // 64 bytes
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[FieldOffset(64)] public byte Buffer; // 256 bytes
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[FieldOffset(320)] public int IsHash64; // 4 bytes
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[FieldOffset(324)] public int BufferedSize; // 4 bytes
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[FieldOffset(328)] public int NbStripesSoFar; // 4 bytes + 4 padding
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[FieldOffset(336)] public long TotalLength; // 8 bytes
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[FieldOffset(344)] public ulong Seed; // 8 bytes
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[FieldOffset(352)] public byte SecretKey; // 192 bytes
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[FieldOffset(540)] public byte _PadEnd;
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}
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#endregion
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#region Internals
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private unsafe void DigestLong(ulong* acc, byte* secret, int isHash64)
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{
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UnsafeUtility.MemCpy(acc, Acc, STRIPE_LEN);
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if (State.BufferedSize >= STRIPE_LEN)
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{
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var totalNbStripes = (State.BufferedSize - 1) / STRIPE_LEN;
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ConsumeStripes(acc, ref State.NbStripesSoFar, Buffer, totalNbStripes, secret, isHash64);
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#if !NET_DOTS
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if (X86.Avx2.IsAvx2Supported)
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{
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Avx2Accumulate512(acc, Buffer + State.BufferedSize - STRIPE_LEN, null,
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secret + SECRET_LIMIT - SECRET_LASTACC_START);
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}
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else
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#endif
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{
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DefaultAccumulate512(acc, Buffer + State.BufferedSize - STRIPE_LEN, null,
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secret + SECRET_LIMIT - SECRET_LASTACC_START, isHash64);
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}
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}
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else
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{
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var lastStripe = stackalloc byte[STRIPE_LEN];
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var catchupSize = STRIPE_LEN - State.BufferedSize;
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UnsafeUtility.MemCpy(lastStripe, Buffer + INTERNAL_BUFFER_SIZE - catchupSize, catchupSize);
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UnsafeUtility.MemCpy(lastStripe + catchupSize, Buffer, State.BufferedSize);
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#if !NET_DOTS
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if (X86.Avx2.IsAvx2Supported)
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{
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Avx2Accumulate512(acc, lastStripe, null, secret+SECRET_LIMIT-SECRET_LASTACC_START);
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}
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else
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#endif
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{
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DefaultAccumulate512(acc, lastStripe, null, secret+SECRET_LIMIT-SECRET_LASTACC_START, isHash64);
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}
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}
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}
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private unsafe void ConsumeStripes(ulong* acc, ref int nbStripesSoFar, byte* input, long totalStripes,
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byte* secret, int isHash64)
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{
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if (NB_STRIPES_PER_BLOCK - nbStripesSoFar <= totalStripes)
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{
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var nbStripes = NB_STRIPES_PER_BLOCK - nbStripesSoFar;
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#if !NET_DOTS
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if (X86.Avx2.IsAvx2Supported)
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{
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Avx2Accumulate(acc, input, null, secret + nbStripesSoFar * SECRET_CONSUME_RATE, nbStripes, isHash64);
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Avx2ScrambleAcc(acc, secret + SECRET_LIMIT);
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Avx2Accumulate(acc, input + nbStripes * STRIPE_LEN, null, secret, totalStripes - nbStripes, isHash64);
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}
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else
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#endif
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{
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DefaultAccumulate(acc, input, null, secret + nbStripesSoFar * SECRET_CONSUME_RATE, nbStripes, isHash64);
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DefaultScrambleAcc(acc, secret + SECRET_LIMIT);
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DefaultAccumulate(acc, input + nbStripes * STRIPE_LEN, null, secret, totalStripes - nbStripes, isHash64);
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}
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nbStripesSoFar = (int) totalStripes - nbStripes;
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}
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else
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{
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#if !NET_DOTS
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if (X86.Avx2.IsAvx2Supported)
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{
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Avx2Accumulate(acc, input, null, secret + nbStripesSoFar * SECRET_CONSUME_RATE, totalStripes, isHash64);
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}
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else
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#endif
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{
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DefaultAccumulate(acc, input, null, secret + nbStripesSoFar * SECRET_CONSUME_RATE, totalStripes, isHash64);
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}
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nbStripesSoFar += (int) totalStripes;
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}
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}
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[Conditional("ENABLE_UNITY_COLLECTIONS_CHECKS")]
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[BurstDiscard]
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void CheckKeySize(int isHash64)
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{
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if (State.IsHash64 != isHash64)
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{
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var s = State.IsHash64 != 0 ? "64" : "128";
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throw new InvalidOperationException(
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$"The streaming state was create for {s} bits hash key, the calling method doesn't support this key size, please use the appropriate API");
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}
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}
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#endregion
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}
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}
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}
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