update

2022-12-13 22:47:31 +08:00
parent 9e7b10c1a5
commit df178687ba
40 changed files with 5401 additions and 15 deletions
@@ -0,0 +1,170 @@
+using System;
+using System.Text;
+
+namespace BaseNcoding
+{
+	public class Base64 : Base
+	{
+		public const string DefaultAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+		public const char DefaultSpecial = '=';
+
+		public override bool HasSpecial => true;
+
+		public Base64(string alphabet = DefaultAlphabet, char special = DefaultSpecial,
+			Encoding textEncoding = null, bool parallel = false)
+			: base(64, alphabet, special, textEncoding, parallel)
+		{
+		}
+
+		public override string Encode(byte[] data)
+		{
+			int resultLength = (data.Length + 2) / 3 * 4;
+			char[] result = new char[resultLength];
+
+			int length3 = data.Length / 3;
+			if (!Parallel)
+			{
+				EncodeBlock(data, result, 0, length3);
+			}
+			else
+			{
+				int processorCount = Math.Min(length3, Environment.ProcessorCount);
+				System.Threading.Tasks.Parallel.For(0, processorCount, i =>
+				{
+					int beginInd = i * length3 / processorCount;
+					int endInd = (i + 1) * length3 / processorCount;
+					EncodeBlock(data, result, beginInd, endInd);
+				});
+			}
+
+			int ind;
+			int x1, x2;
+			int srcInd, dstInd;
+			switch (data.Length - length3 * 3)
+			{
+				case 1:
+					ind = length3;
+					srcInd = ind * 3;
+					dstInd = ind * 4;
+					x1 = data[srcInd];
+					result[dstInd] = Alphabet[x1 >> 2];
+					result[dstInd + 1] = Alphabet[(x1 << 4) & 0x30];
+					result[dstInd + 2] = Special;
+					result[dstInd + 3] = Special;
+					break;
+				case 2:
+					ind = length3;
+					srcInd = ind * 3;
+					dstInd = ind * 4;
+					x1 = data[srcInd];
+					x2 = data[srcInd + 1];
+					result[dstInd] = Alphabet[x1 >> 2];
+					result[dstInd + 1] = Alphabet[((x1 << 4) & 0x30) | (x2 >> 4)];
+					result[dstInd + 2] = Alphabet[(x2 << 2) & 0x3C];
+					result[dstInd + 3] = Special;
+					break;
+			}
+
+			return new string(result);
+		}
+
+		public override byte[] Decode(string data)
+		{
+			unchecked
+			{
+				if (string.IsNullOrEmpty(data))
+					return new byte[0];
+
+				int lastSpecialInd = data.Length;
+				while (data[lastSpecialInd - 1] == Special)
+					lastSpecialInd--;
+				int tailLength = data.Length - lastSpecialInd;
+
+				int resultLength = (data.Length + 3) / 4 * 3 - tailLength;
+				byte[] result = new byte[resultLength];
+
+				int length4 = (data.Length - tailLength) / 4;
+				if (!Parallel)
+				{
+					DecodeBlock(data, result, 0, length4);
+				}
+				else
+				{
+					int processorCount = Math.Min(length4, Environment.ProcessorCount);
+					System.Threading.Tasks.Parallel.For(0, processorCount, i =>
+					{
+						int beginInd = i * length4 / processorCount;
+						int endInd = (i + 1) * length4 / processorCount;
+						DecodeBlock(data, result, beginInd, endInd);
+					});
+				}
+
+				int ind;
+				int x1, x2, x3;
+				int srcInd, dstInd;
+				switch (tailLength)
+				{
+					case 2:
+						ind = length4;
+						srcInd = ind * 4;
+						dstInd = ind * 3;
+						x1 = InvAlphabet[data[srcInd]];
+						x2 = InvAlphabet[data[srcInd + 1]];
+						result[dstInd] = (byte)((x1 << 2) | ((x2 >> 4) & 0x3));
+						break;
+					case 1:
+						ind = length4;
+						srcInd = ind * 4;
+						dstInd = ind * 3;
+						x1 = InvAlphabet[data[srcInd]];
+						x2 = InvAlphabet[data[srcInd + 1]];
+						x3 = InvAlphabet[data[srcInd + 2]];
+						result[dstInd] = (byte)((x1 << 2) | ((x2 >> 4) & 0x3));
+						result[dstInd + 1] = (byte)((x2 << 4) | ((x3 >> 2) & 0xF));
+						break;
+				}
+
+				return result;
+			}
+		}
+
+		private void EncodeBlock(byte[] src, char[] dst, int beginInd, int endInd)
+		{
+			for (int ind = beginInd; ind < endInd; ind++)
+			{
+				int srcInd = ind * 3;
+				int dstInd = ind * 4;
+
+				byte x1 = src[srcInd];
+				byte x2 = src[srcInd + 1];
+				byte x3 = src[srcInd + 2];
+
+				dst[dstInd] = Alphabet[x1 >> 2];
+				dst[dstInd + 1] = Alphabet[((x1 << 4) & 0x30) | (x2 >> 4)];
+				dst[dstInd + 2] = Alphabet[((x2 << 2) & 0x3C) | (x3 >> 6)];
+				dst[dstInd + 3] = Alphabet[x3 & 0x3F];
+			}
+		}
+
+		private void DecodeBlock(string src, byte[] dst, int beginInd, int endInd)
+		{
+			unchecked
+			{
+				for (int ind = beginInd; ind < endInd; ind++)
+				{
+					int srcInd = ind * 4;
+					int dstInd = ind * 3;
+
+					int x1 = InvAlphabet[src[srcInd]];
+					int x2 = InvAlphabet[src[srcInd + 1]];
+					int x3 = InvAlphabet[src[srcInd + 2]];
+					int x4 = InvAlphabet[src[srcInd + 3]];
+
+					dst[dstInd] = (byte)((x1 << 2) | ((x2 >> 4) & 0x3));
+					dst[dstInd + 1] = (byte)((x2 << 4) | ((x3 >> 2) & 0xF));
+					dst[dstInd + 2] = (byte)((x3 << 6) | (x4 & 0x3F));
+				}
+			}
+		}
+	}
+}