Fowler–Noll–Vo 1 A (FNV1) in 32 bit and 64 bit variants

32and64bit.cs

using System;
using System.Text;

namespace Hashing
{
	public static class FowlerNollVo
	{
		public static string ToFnv1aHashInt64(this string text)
		{
			string Fnv1a(byte[] bytes_)
			{
				const ulong offset = 14695981039346656037;
				const ulong prime = 1099511628211;
				ulong hash = offset;

				for (var i = 0; i < bytes_.Length; i++)
				{
					unchecked
					{
						hash ^= bytes_[i];
						hash *= prime;
					}
				}

				return Convert.ToBase64String(BitConverter.GetBytes(hash));
			}

			byte[] bytes = Encoding.UTF8.GetBytes(text);
			return Fnv1a(bytes);
		}

		public static string ToFnv1aHashInt32(this string text)
		{
			string Fnv1a(byte[] bytes_)
			{
				const uint offset = 0x811C9DC5;
				const uint prime = 0x01000193;
				uint hash = offset;

				for (var i = 0; i < bytes_.Length; i++)
				{
					unchecked
					{
						hash ^= bytes_[i];
						hash *= prime;
					}
				}

				// return BitConverter.ToInt64(bytes_, 0);
				return Convert.ToBase64String(BitConverter.GetBytes(hash));
			}

			byte[] bytes = Encoding.UTF8.GetBytes(text);
			return Fnv1a(bytes);
		}
	}
}

links.md

• https://softwareengineering.stackexchange.com/questions/49550/which-hashing-algorithm-is-best-for-uniqueness-and-speed
• https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function#FNV-1a_hash
• http://www.isthe.com/chongo/tech/comp/fnv/index.html
• https://github.com/ssg/HashDepot
• https://gist.github.com/rasmuskl/3786618