Make galois field constants

Author: Shane32

QRCoder/QRCodeGenerator.cs

@@ -18,8 +18,8 @@ public class QRCodeGenerator : IDisposable
         private static readonly Dictionary<int, AlignmentPattern> alignmentPatternTable = CreateAlignmentPatternTable();
         private static readonly List<ECCInfo> capacityECCTable = CreateCapacityECCTable();
         private static readonly List<VersionInfo> capacityTable = CreateCapacityTable();
-        private static readonly int[] galoisFieldByExponentAlpha;
-        private static readonly int[] galoisFieldByIntegerValue;
+        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 };
         private static readonly Dictionary<char, int> alphanumEncDict = CreateAlphanumEncDict();
 
         public enum EciMode
@@ -37,19 +37,6 @@ public QRCodeGenerator()
         {
         }
 
-        static QRCodeGenerator()
-        {
-            var galoisField = CreateAntilogTable();
-            galoisFieldByExponentAlpha = new int[256];
-            galoisFieldByIntegerValue = new int[256];
-            for (int i = 255; i >= 0; i--) // the value 1 occurs twice in the galois field, so we start from the end to get the correct value
-            {
-                var entry = galoisField[i];
-                galoisFieldByExponentAlpha[entry.ExponentAlpha] = checked((byte)entry.IntegerValue);
-                galoisFieldByIntegerValue[entry.IntegerValue] = checked((byte)entry.ExponentAlpha);
-            }
-        }
-
         /// <summary>
         /// Calculates the QR code data which than can be used in one of the rendering classes to generate a graphical representation.
         /// </summary>
@@ -1536,21 +1523,6 @@ private static List<VersionInfo> CreateCapacityTable()
             return localCapacityTable;
         }
 
-        private static List<Antilog> CreateAntilogTable()
-        {
-            var localGaloisField = new List<Antilog>(256);
-
-            int gfItem = 1;
-            for (var i = 0; i < 256; i++)
-            {
-                localGaloisField.Add(new Antilog(i, gfItem));
-                gfItem *= 2;
-                if (gfItem > 255)
-                    gfItem ^= 285;
-            }
-            return localGaloisField;
-        }
-
         /// <summary>
         /// Error correction level. These define the tolerance levels for how much of the code can be lost before the code cannot be recovered.
         /// </summary>
@@ -1648,17 +1620,6 @@ public VersionInfoDetails(ECCLevel errorCorrectionLevel, Dictionary<EncodingMode
             public Dictionary<EncodingMode, int> CapacityDict { get; }
         }
 
-        private struct Antilog
-        {
-            public Antilog(int exponentAlpha, int integerValue)
-            {
-                this.ExponentAlpha = exponentAlpha;
-                this.IntegerValue = integerValue;
-            }
-            public int ExponentAlpha { get; }
-            public int IntegerValue { get; }
-        }
-
         private struct PolynomItem
         {
             public PolynomItem(int coefficient, int exponent)