DTLib.XXHash/README.md

Extremely fast non-cryptographic hash algorithm xxhash

xxHash is an Extremely fast Hash algorithm, running at RAM speed limits. It successfully completes the SMHasher test suite which evaluates collision, dispersion and randomness qualities of hash functions.

Instalation

PM> Install-Package Standart.Hash.xxHash

Benchmarks

This benchmark was launched on a Windows 10 (10.0.16299.309). The reference system uses a Intel Core i7-4700MQ CPU 2.40GHz (Haswell)

Method	x64
Hash32 Array	5.05 GB/s
Hash64 Array	8.92 GB/s
Hash32 Span	5.05 GB/s
Hash64 Span	8.92 GB/s
Hash32 Stream	3.22 GB/s
Hash64 Stream	4.81 GB/s

Comparison between С# and C implementation

Method	Time
Hash32 C# 1KB	185.1 ns
Hash32 C 1KB	183.5 ns
Hash64 C# 1KB	117.3 ns
Hash64 C 1KB	104.8 ns
Hash32 C# 1MB	170.6 us
Hash32 C 1MB	170.1 us
Hash64 C# 1MB	87.1 us
Hash64 C 1MB	85.3 us
Hash32 C# 1GB	193.6 ms
Hash32 C 1GB	190.8 ms
Hash64 C# 1GB	116.9 ms
Hash64 C 1GB	114.1 ms

Defference

Method	Platform	Language	Size	Time	Speed	Difference
Hash32	x64	C#	1GB	193.6 ms	5.16 GB/s	1.4 %
Hash32	x64	C	1GB	190.8 ms	5.24 GB/s	1.4 %
Hash64	x64	C#	1GB	116.9 ms	8.55 GB/s	2.4 %
Hash64	x64	C	1GB	114.1 ms	8.76 GB/s	2.4 %

Api

public static uint ComputeHash(byte[] data, int length, uint seed = 0) { throw null; }
public static uint ComputeHash(Span<byte> data, int length, uint seed = 0) { throw null; }
public static uint ComputeHash(Stream stream, int bufferSize = 4096, uint seed = 0) { throw null; }
public static async Task<uint> ComputeHashAsync(Stream stream, int bufferSize = 4096, uint seed = 0) { throw null; }

public static ulong ComputeHash(byte[] data, int length, ulong seed = 0) { throw null; }
public static ulong ComputeHash(Span<byte> data, int length, ulong seed = 0) { throw null; }
public static ulong ComputeHash(Stream stream, int bufferSize = 8192, ulong seed = 0) { throw null; }
public static async Task<ulong> ComputeHashAsync(Stream stream, int bufferSize = 8192, ulong seed = 0) { throw null; }

Examples

A few examples of how to use api

byte[] data = Encoding.UTF8.GetBytes("veni vidi vici");

ulong h64_1 = xxHash64.ComputeHash(data, data.Length);
ulong h64_2 = xxHash64.ComputeHash(new MemoryStream(data));
ulong h64_3 = await xxHash64.ComputeHashAsync(new MemoryStream(data));

uint h32_1 = xxHash32.ComputeHash(data, data.Length);
uint h32_2 = xxHash32.ComputeHash(new MemoryStream(data));
uint h32_3 = await xxHash32.ComputeHashAsync(new MemoryStream(data));

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