AddUserSecrets, RenameByDateTaken and BlurHash

BlurHash.Core/Base83.cs

@@ -0,0 +1,64 @@
+namespace BlurHash;
+
+/// <summary>
+/// Contains methods to encode or decode integers to Base83-Strings
+/// </summary>
+internal static class Base83
+{
+    internal const string _Charset = @"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz#$%*+,-.:;=?@[]^_{|}~";
+
+    private static readonly IReadOnlyDictionary<char, int> _ReverseLookup;
+
+    static Base83()
+    {
+        // Build inverse lookup table for fast decoding
+        Dictionary<char, int> charIndices = new();
+        int index = 0;
+        foreach (char c in _Charset)
+        {
+            charIndices[c] = index;
+            index++;
+        }
+
+        _ReverseLookup = charIndices;
+    }
+
+    /// <summary>
+    /// Encodes a number into its Base83-representation
+    /// </summary>
+    /// <param name="number">The number to encode</param>
+    /// <param name="output">The data buffer to put the result data into</param>
+    /// <returns>The Base83-representation of the number</returns>
+    public static void EncodeBase83(this int number, Span<char> output)
+    {
+        int length = output.Length;
+        for (int i = 0; i < length; i++)
+        {
+            int digit = number % 83;
+            number /= 83;
+            output[length - i - 1] = _Charset[digit];
+        }
+    }
+
+    /// <summary>
+    /// Decodes an <code>IEnumerable</code> of Base83-characters into the integral value it represents
+    /// </summary>
+    /// <param name="base83Data">The characters to decode</param>
+    /// <returns>The decoded value as integer</returns>
+    public static int DecodeBase83(this ReadOnlySpan<char> base83Data)
+    {
+        int result = 0;
+        foreach (char c in base83Data)
+        {
+            if (!_ReverseLookup.TryGetValue(c, out int digit))
+            {
+                throw new ArgumentException("The given string contains invalid characters.", nameof(base83Data));
+            }
+
+            result *= 83;
+            result += digit;
+        }
+
+        return result;
+    }
+}