Optimize alphanumeric encoder and galois field constants

Directory.Build.targets

@@ -7,7 +7,7 @@
   </PropertyGroup>
 
   <!-- Strong name signing for Release builds of packable projects -->
-  <PropertyGroup Condition="'$(Configuration)' == 'Release' AND '$(IsPackable)' == 'true'">
+  <PropertyGroup Condition="'$(Configuration)' == 'Release'">
     <SignAssembly>true</SignAssembly>
     <DelaySign>false</DelaySign>
   </PropertyGroup>

QRCoder/PayloadGenerator.cs

@@ -14,7 +14,7 @@ public static partial class PayloadGenerator
     /// </summary>
     /// <param name="iban">The IBAN to validate.</param>
     /// <returns>True if the IBAN is valid; otherwise, false.</returns>
-    private static bool IsValidIban(string iban)
+    internal static bool IsValidIban(string iban)
     {
         //Clean IBAN
         var ibanCleared = iban.ToUpperInvariant().Replace(" ", "").Replace("-", "");
@@ -48,7 +48,7 @@ private static bool IsValidIban(string iban)
     /// </summary>
     /// <param name="iban">The QR IBAN to validate.</param>
     /// <returns>True if the QR IBAN is valid; otherwise, false.</returns>
-    private static bool IsValidQRIban(string iban)
+    internal static bool IsValidQRIban(string iban)
     {
         var foundQrIid = false;
         try

QRCoder/QRCodeGenerator.cs

@@ -750,7 +750,7 @@ private static void ConvertToDecNotationInPlace(Polynom poly)
     /// Determines the most efficient encoding mode for the given plain text based on its character content
     /// and a flag indicating whether to force UTF-8 encoding.
     /// </summary>
-    private static EncodingMode GetEncodingFromPlaintext(string plainText, bool forceUtf8)
+    internal static EncodingMode GetEncodingFromPlaintext(string plainText, bool forceUtf8)
     {
         if (forceUtf8)
             return EncodingMode.Byte;
@@ -760,7 +760,7 @@ private static EncodingMode GetEncodingFromPlaintext(string plainText, bool forc
             if (IsInRange(c, '0', '9'))
                 continue;   // numeric - char.IsDigit() for Latin1
             result = EncodingMode.Alphanumeric;     // not numeric, assume alphanumeric
-            if (AlphanumericEncoder.CanEncodeNonDigit(c))
+            if (AlphanumericEncoder.CanEncode(c))
                 continue; // alphanumeric
             return EncodingMode.Byte;               // not numeric or alphanumeric, assume byte
         }

QRCoder/QRCodeGenerator/AlphanumericEncoder.cs

@@ -5,40 +5,36 @@ public partial class QRCodeGenerator
     /// <summary>
     /// Encodes alphanumeric characters (<c>0–9</c>, <c>A–Z</c> (uppercase), space, <c>$</c>, <c>%</c>, <c>*</c>, <c>+</c>, <c>-</c>, period, <c>/</c>, colon) into a binary format suitable for QR codes.
     /// </summary>
-    private static class AlphanumericEncoder
+    internal static class AlphanumericEncoder
     {
-        private static readonly char[] _alphanumEncTable = { ' ', '$', '%', '*', '+', '-', '.', '/', ':' };
+#if HAS_SPAN
+        // With C# 7.3 and later, this byte array is inlined into the assembly's read-only data section, improving performance and reducing memory usage.
+        // See: https://devblogs.microsoft.com/dotnet/performance-improvements-in-net-core-3-0/
+        internal static ReadOnlySpan<byte> _map =>
+#else
+        internal static readonly byte[] _map =
+#endif
+        [
+            // 0..31
+            255, 255, 255, 255, 255, 255, 255, 255,
+            255, 255, 255, 255, 255, 255, 255, 255,
+            255, 255, 255, 255, 255, 255, 255, 255,
+            255, 255, 255, 255, 255, 255, 255, 255,
+            // 32..47  (space, ! " # $ % & ' ( ) * + , - . /)
+            36, 255, 255, 255, 37, 38, 255, 255, 255, 255, 39, 40, 255, 41, 42, 43,
+            // 48..57  (0..9)
+            0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+            // 58..64  (: ; < = > ? @)
+            44, 255, 255, 255, 255, 255, 255,
+            // 65..90  (A..Z)
+            10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35
+            // (we don't index > 90)
+        ];
 
         /// <summary>
-        /// A dictionary mapping alphanumeric characters to their respective positions used in QR code encoding.
-        /// This includes digits 0-9, uppercase letters A-Z, and some special characters.
+        /// Checks if a character is present in the alphanumeric encoding table.
         /// </summary>
-        private static readonly Dictionary<char, int> _alphanumEncDict = CreateAlphanumEncDict(_alphanumEncTable);
-
-        /// <summary>
-        /// Creates a dictionary mapping alphanumeric characters to their respective positions used in QR code encoding.
-        /// This includes digits 0-9, uppercase letters A-Z, and some special characters.
-        /// </summary>
-        /// <returns>A dictionary mapping each supported alphanumeric character to its corresponding value.</returns>
-        private static Dictionary<char, int> CreateAlphanumEncDict(char[] alphanumEncTable)
-        {
-            var localAlphanumEncDict = new Dictionary<char, int>(45);
-            // Add 0-9
-            for (char c = '0'; c <= '9'; c++)
-                localAlphanumEncDict.Add(c, c - '0');
-            // Add uppercase alphabetic characters.
-            for (char c = 'A'; c <= 'Z'; c++)
-                localAlphanumEncDict.Add(c, localAlphanumEncDict.Count);
-            // Add special characters from a predefined table.
-            for (int i = 0; i < _alphanumEncTable.Length; i++)
-                localAlphanumEncDict.Add(alphanumEncTable[i], localAlphanumEncDict.Count);
-            return localAlphanumEncDict;
-        }
-
-        /// <summary>
-        /// Checks if a non-digit character is present in the alphanumeric encoding table.
-        /// </summary>
-        public static bool CanEncodeNonDigit(char c) => IsInRange(c, 'A', 'Z') || Array.IndexOf(_alphanumEncTable, c) >= 0;
+        public static bool CanEncode(char c) => c <= 90 && _map[c] != 255;
 
         /// <summary>
         /// Calculates the bit length required to encode alphanumeric text of a given length.
@@ -81,7 +77,7 @@ public static int WriteToBitArray(string plainText, int index, int count, BitArr
             while (count >= 2)
             {
                 // Convert each pair of characters to a number by looking them up in the alphanumeric dictionary and calculating.
-                var dec = _alphanumEncDict[plainText[index++]] * 45 + _alphanumEncDict[plainText[index++]];
+                var dec = _map[plainText[index++]] * 45 + _map[plainText[index++]];
                 // Convert the number to binary and store it in the BitArray.
                 codeIndex = DecToBin(dec, 11, codeText, codeIndex);
                 count -= 2;
@@ -90,7 +86,7 @@ public static int WriteToBitArray(string plainText, int index, int count, BitArr
             // Handle the last character if the length is odd.
             if (count > 0)
             {
-                codeIndex = DecToBin(_alphanumEncDict[plainText[index]], 6, codeText, codeIndex);
+                codeIndex = DecToBin(_map[plainText[index]], 6, codeText, codeIndex);
             }
 
             return codeIndex;

QRCoder/QRCodeGenerator/EncodingMode.cs

@@ -5,7 +5,7 @@ public partial class QRCodeGenerator
     /// <summary>
     /// Specifies the encoding modes for the characters in a QR code.
     /// </summary>
-    private enum EncodingMode
+    internal enum EncodingMode
     {
         /// <summary>
         /// Numeric encoding mode, which is used to encode numeric data (digits 0-9).

QRCoder/QRCodeGenerator/GaloisField.cs

@@ -13,10 +13,21 @@ public partial class QRCodeGenerator
     /// polynomial and used for efficient encoding and decoding operations.
     /// </para>
     /// </summary>
-    private static class GaloisField
+    internal static class GaloisField
     {
-        private static readonly int[] _galoisFieldByExponentAlpha = { 1, 2, 4, 8, 16, 32, 64, 128, 29, 58, 116, 232, 205, 135, 19, 38, 76, 152, 45, 90, 180, 117, 234, 201, 143, 3, 6, 12, 24, 48, 96, 192, 157, 39, 78, 156, 37, 74, 148, 53, 106, 212, 181, 119, 238, 193, 159, 35, 70, 140, 5, 10, 20, 40, 80, 160, 93, 186, 105, 210, 185, 111, 222, 161, 95, 190, 97, 194, 153, 47, 94, 188, 101, 202, 137, 15, 30, 60, 120, 240, 253, 231, 211, 187, 107, 214, 177, 127, 254, 225, 223, 163, 91, 182, 113, 226, 217, 175, 67, 134, 17, 34, 68, 136, 13, 26, 52, 104, 208, 189, 103, 206, 129, 31, 62, 124, 248, 237, 199, 147, 59, 118, 236, 197, 151, 51, 102, 204, 133, 23, 46, 92, 184, 109, 218, 169, 79, 158, 33, 66, 132, 21, 42, 84, 168, 77, 154, 41, 82, 164, 85, 170, 73, 146, 57, 114, 228, 213, 183, 115, 230, 209, 191, 99, 198, 145, 63, 126, 252, 229, 215, 179, 123, 246, 241, 255, 227, 219, 171, 75, 150, 49, 98, 196, 149, 55, 110, 220, 165, 87, 174, 65, 130, 25, 50, 100, 200, 141, 7, 14, 28, 56, 112, 224, 221, 167, 83, 166, 81, 162, 89, 178, 121, 242, 249, 239, 195, 155, 43, 86, 172, 69, 138, 9, 18, 36, 72, 144, 61, 122, 244, 245, 247, 243, 251, 235, 203, 139, 11, 22, 44, 88, 176, 125, 250, 233, 207, 131, 27, 54, 108, 216, 173, 71, 142, 1 };
-        private static readonly int[] _galoisFieldByIntegerValue = { 0, 0, 1, 25, 2, 50, 26, 198, 3, 223, 51, 238, 27, 104, 199, 75, 4, 100, 224, 14, 52, 141, 239, 129, 28, 193, 105, 248, 200, 8, 76, 113, 5, 138, 101, 47, 225, 36, 15, 33, 53, 147, 142, 218, 240, 18, 130, 69, 29, 181, 194, 125, 106, 39, 249, 185, 201, 154, 9, 120, 77, 228, 114, 166, 6, 191, 139, 98, 102, 221, 48, 253, 226, 152, 37, 179, 16, 145, 34, 136, 54, 208, 148, 206, 143, 150, 219, 189, 241, 210, 19, 92, 131, 56, 70, 64, 30, 66, 182, 163, 195, 72, 126, 110, 107, 58, 40, 84, 250, 133, 186, 61, 202, 94, 155, 159, 10, 21, 121, 43, 78, 212, 229, 172, 115, 243, 167, 87, 7, 112, 192, 247, 140, 128, 99, 13, 103, 74, 222, 237, 49, 197, 254, 24, 227, 165, 153, 119, 38, 184, 180, 124, 17, 68, 146, 217, 35, 32, 137, 46, 55, 63, 209, 91, 149, 188, 207, 205, 144, 135, 151, 178, 220, 252, 190, 97, 242, 86, 211, 171, 20, 42, 93, 158, 132, 60, 57, 83, 71, 109, 65, 162, 31, 45, 67, 216, 183, 123, 164, 118, 196, 23, 73, 236, 127, 12, 111, 246, 108, 161, 59, 82, 41, 157, 85, 170, 251, 96, 134, 177, 187, 204, 62, 90, 203, 89, 95, 176, 156, 169, 160, 81, 11, 245, 22, 235, 122, 117, 44, 215, 79, 174, 213, 233, 230, 231, 173, 232, 116, 214, 244, 234, 168, 80, 88, 175 };
+#if HAS_SPAN
+        internal static ReadOnlySpan<byte> _galoisFieldByExponentAlpha =>
+#else
+        internal static readonly byte[] _galoisFieldByExponentAlpha =
+#endif
+            [1, 2, 4, 8, 16, 32, 64, 128, 29, 58, 116, 232, 205, 135, 19, 38, 76, 152, 45, 90, 180, 117, 234, 201, 143, 3, 6, 12, 24, 48, 96, 192, 157, 39, 78, 156, 37, 74, 148, 53, 106, 212, 181, 119, 238, 193, 159, 35, 70, 140, 5, 10, 20, 40, 80, 160, 93, 186, 105, 210, 185, 111, 222, 161, 95, 190, 97, 194, 153, 47, 94, 188, 101, 202, 137, 15, 30, 60, 120, 240, 253, 231, 211, 187, 107, 214, 177, 127, 254, 225, 223, 163, 91, 182, 113, 226, 217, 175, 67, 134, 17, 34, 68, 136, 13, 26, 52, 104, 208, 189, 103, 206, 129, 31, 62, 124, 248, 237, 199, 147, 59, 118, 236, 197, 151, 51, 102, 204, 133, 23, 46, 92, 184, 109, 218, 169, 79, 158, 33, 66, 132, 21, 42, 84, 168, 77, 154, 41, 82, 164, 85, 170, 73, 146, 57, 114, 228, 213, 183, 115, 230, 209, 191, 99, 198, 145, 63, 126, 252, 229, 215, 179, 123, 246, 241, 255, 227, 219, 171, 75, 150, 49, 98, 196, 149, 55, 110, 220, 165, 87, 174, 65, 130, 25, 50, 100, 200, 141, 7, 14, 28, 56, 112, 224, 221, 167, 83, 166, 81, 162, 89, 178, 121, 242, 249, 239, 195, 155, 43, 86, 172, 69, 138, 9, 18, 36, 72, 144, 61, 122, 244, 245, 247, 243, 251, 235, 203, 139, 11, 22, 44, 88, 176, 125, 250, 233, 207, 131, 27, 54, 108, 216, 173, 71, 142, 1];
+
+#if HAS_SPAN
+        internal static ReadOnlySpan<byte> _galoisFieldByIntegerValue =>
+#else
+        internal static readonly byte[] _galoisFieldByIntegerValue =
+#endif
+            [0, 0, 1, 25, 2, 50, 26, 198, 3, 223, 51, 238, 27, 104, 199, 75, 4, 100, 224, 14, 52, 141, 239, 129, 28, 193, 105, 248, 200, 8, 76, 113, 5, 138, 101, 47, 225, 36, 15, 33, 53, 147, 142, 218, 240, 18, 130, 69, 29, 181, 194, 125, 106, 39, 249, 185, 201, 154, 9, 120, 77, 228, 114, 166, 6, 191, 139, 98, 102, 221, 48, 253, 226, 152, 37, 179, 16, 145, 34, 136, 54, 208, 148, 206, 143, 150, 219, 189, 241, 210, 19, 92, 131, 56, 70, 64, 30, 66, 182, 163, 195, 72, 126, 110, 107, 58, 40, 84, 250, 133, 186, 61, 202, 94, 155, 159, 10, 21, 121, 43, 78, 212, 229, 172, 115, 243, 167, 87, 7, 112, 192, 247, 140, 128, 99, 13, 103, 74, 222, 237, 49, 197, 254, 24, 227, 165, 153, 119, 38, 184, 180, 124, 17, 68, 146, 217, 35, 32, 137, 46, 55, 63, 209, 91, 149, 188, 207, 205, 144, 135, 151, 178, 220, 252, 190, 97, 242, 86, 211, 171, 20, 42, 93, 158, 132, 60, 57, 83, 71, 109, 65, 162, 31, 45, 67, 216, 183, 123, 164, 118, 196, 23, 73, 236, 127, 12, 111, 246, 108, 161, 59, 82, 41, 157, 85, 170, 251, 96, 134, 177, 187, 204, 62, 90, 203, 89, 95, 176, 156, 169, 160, 81, 11, 245, 22, 235, 122, 117, 44, 215, 79, 174, 213, 233, 230, 231, 173, 232, 116, 214, 244, 234, 168, 80, 88, 175];
 
         /// <summary>
         /// Retrieves the integer value from the Galois field that corresponds to a given exponent.

QRCoder/QRCodeGenerator/OptimizedDataSegment.cs

@@ -175,7 +175,7 @@ private static EncodingMode SelectInitialMode(string text, int startPos, int ver
                 if (numericCount < threshold)
                 {
                     var nextPos = startPos + numericCount;
-                    if (nextPos < text.Length && !IsAlphanumericNonDigit(text[nextPos]))
+                    if (nextPos < text.Length && !IsAlphanumeric(text[nextPos]))
                         return EncodingMode.Byte;
                 }
                 // ELSE IF there are less than [7-9] characters followed by data from the exclusive subset of the Alphanumeric character set
@@ -184,7 +184,7 @@ private static EncodingMode SelectInitialMode(string text, int startPos, int ver
                 if (numericCount < threshold)
                 {
                     var nextPos = startPos + numericCount;
-                    if (nextPos < text.Length && IsAlphanumericNonDigit(text[nextPos]))
+                    if (nextPos < text.Length && IsAlphanumeric(text[nextPos]))
                         return EncodingMode.Alphanumeric;
                 }
                 return EncodingMode.Numeric;
@@ -329,9 +329,6 @@ private static int CountConsecutive(string text, int startPos, Func<char, bool>
         private static bool IsNumeric(char c) => IsInRange(c, '0', '9');
 
         // Checks if a character is alphanumeric (can be encoded in alphanumeric mode).
-        private static bool IsAlphanumeric(char c) => IsNumeric(c) || IsAlphanumericNonDigit(c);
-
-        // Checks if a non-digit character can be encoded in alphanumeric mode.
-        private static bool IsAlphanumericNonDigit(char c) => AlphanumericEncoder.CanEncodeNonDigit(c);
+        private static bool IsAlphanumeric(char c) => AlphanumericEncoder.CanEncode(c);
     }
 }

QRCoder/QRCoder.csproj

@@ -16,6 +16,14 @@
     <Guid>e668b98b-83bb-4e60-b33c-4fd5ed9c0156</Guid>
   </PropertyGroup>
 
+  <ItemGroup Condition="'$(Configuration)' == 'Release'">
+    <InternalsVisibleTo Include="QRCoderTests, PublicKey=002400000480000094000000060200000024000052534131000400000100010071e74d3f6dcbba7726fcbb7ad05a2dfa3b8e13f9bf2938c05de266a83a7f3c95201b7cdc9e1f88842093ece868c3ec7874e3b8907008763c85711bf0e2e9757a3068385380a757bd52fa77248f227f602b0785e040756ef42dabc7de7f8376847c71b3f20356a9176cc88067583ee3501e61f8aa07bdd70f41418986fb79a1a3" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(Configuration)' != 'Release'">
+    <InternalsVisibleTo Include="QRCoderTests" />
+  </ItemGroup>
+
   <ItemGroup Condition=" '$(TargetFramework)' == 'net35' OR '$(TargetFramework)' == 'net40' ">
     <Reference Include="PresentationCore" />
     <Reference Include="PresentationFramework" />

QRCoderTests/PayloadGeneratorTests/IbanTests.cs

@@ -1,5 +1,3 @@
-using System.Reflection;
-
 namespace QRCoderTests.PayloadGeneratorTests;
 
 public class IbanTests
@@ -9,8 +7,7 @@ public void iban_validator_validate_german_iban()
     {
         var iban = "DE15268500010154131577";
 
-        var method = typeof(PayloadGenerator).GetMethod("IsValidIban", BindingFlags.NonPublic | BindingFlags.Static);
-        var result = (bool)method!.Invoke(null, new object[] { iban })!;
+        var result = PayloadGenerator.IsValidIban(iban);
 
         result.ShouldBe<bool>(true);
     }
@@ -20,8 +17,7 @@ public void iban_validator_validate_swiss_iban()
     {
         var iban = "CH1900767000U00121977";
 
-        var method = typeof(PayloadGenerator).GetMethod("IsValidIban", BindingFlags.NonPublic | BindingFlags.Static);
-        var result = (bool)method!.Invoke(null, new object[] { iban })!;
+        var result = PayloadGenerator.IsValidIban(iban);
 
         result.ShouldBe<bool>(true);
     }
@@ -31,8 +27,7 @@ public void iban_validator_invalidates_iban()
     {
         var iban = "DE29268500010154131577";
 
-        var method = typeof(PayloadGenerator).GetMethod("IsValidIban", BindingFlags.NonPublic | BindingFlags.Static);
-        var result = (bool)method!.Invoke(null, new object[] { iban })!;
+        var result = PayloadGenerator.IsValidIban(iban);
 
         result.ShouldBe<bool>(false);
     }
@@ -42,8 +37,7 @@ public void qriban_validator_validates_iban()
     {
         var iban = "CH2430043000000789012";
 
-        var method = typeof(PayloadGenerator).GetMethod("IsValidQRIban", BindingFlags.NonPublic | BindingFlags.Static);
-        var result = (bool)method!.Invoke(null, new object[] { iban })!;
+        var result = PayloadGenerator.IsValidQRIban(iban);
 
         result.ShouldBe<bool>(true);
     }
@@ -53,8 +47,7 @@ public void qriban_validator_invalidates_iban()
     {
         var iban = "CH3908704016075473007";
 
-        var method = typeof(PayloadGenerator).GetMethod("IsValidQRIban", BindingFlags.NonPublic | BindingFlags.Static);
-        var result = (bool)method!.Invoke(null, new object[] { iban })!;
+        var result = PayloadGenerator.IsValidQRIban(iban);
 
         result.ShouldBe<bool>(false);
     }

QRCoderTests/QRCoderTests.csproj

@@ -8,6 +8,7 @@
     <SuppressTfmSupportBuildErrors>true</SuppressTfmSupportBuildErrors>
     <RuntimeFrameworkVersion Condition="'$(TargetFramework)' == 'netcoreapp2.1'">2.1.30</RuntimeFrameworkVersion>
     <NoWarn>$(NoWarn);CA1707;CA1416;CA1850</NoWarn>
+    <AssemblyOriginatorKeyFile>..\QRCoder\QRCoderStrongName.snk</AssemblyOriginatorKeyFile>
   </PropertyGroup>
 
   <ItemGroup>