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62 lines
1.9 KiB
C#
62 lines
1.9 KiB
C#
// ReSharper disable MemberCanBePrivate.Global
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namespace SharedTools;
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/// <summary>
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/// Implements the Fowler–Noll–Vo hash function for 32-bit and 64-bit hashes.
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/// </summary>
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public static class FNVHash
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{
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private const uint FNV_OFFSET_BASIS_32_BIT = 2_166_136_261;
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private const ulong FNV_OFFSET_BASIS_64_BIT = 14_695_981_039_346_656_037;
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private const uint FNV_PRIME_32_BIT = 16_777_619;
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private const ulong FNV_PRIME_64_BIT = 1_099_511_628_211;
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/// <summary>
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/// Computes the 32bit FNV-1a hash of a string.
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/// </summary>
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/// <param name="text">The string to hash.</param>
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/// <returns>The 32bit FNV-1a hash of the string.</returns>
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public static uint ToFNV32(this string text) => ToFNV32(text.AsSpan());
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/// <summary>
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/// Computes the 32bit FNV-1a hash of a string.
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/// </summary>
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/// <param name="text">The string to hash.</param>
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/// <returns>The 32bit FNV-1a hash of the string.</returns>
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public static uint ToFNV32(this ReadOnlySpan<char> text)
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{
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var hash = FNV_OFFSET_BASIS_32_BIT;
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foreach (var c in text)
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{
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hash ^= c;
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hash *= FNV_PRIME_32_BIT;
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}
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return hash;
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}
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/// <summary>
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/// Computes the 64bit FNV-1a hash of a string.
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/// </summary>
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/// <param name="text">The string to hash.</param>
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/// <returns>The 64bit FNV-1a hash of the string.</returns>
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public static ulong ToFNV64(this string text) => ToFNV64(text.AsSpan());
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/// <summary>
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/// Computes the 64bit FNV-1a hash of a string.
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/// </summary>
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/// <param name="text">The string to hash.</param>
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/// <returns>The 64bit FNV-1a hash of the string.</returns>
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public static ulong ToFNV64(this ReadOnlySpan<char> text)
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{
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var hash = FNV_OFFSET_BASIS_64_BIT;
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foreach (var c in text)
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{
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hash ^= c;
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hash *= FNV_PRIME_64_BIT;
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}
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return hash;
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}
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} |