Initial data commit

Task/Variable-length-quantity/C-sharp/variable-length-quantity-1.cs

@@ -0,0 +1,104 @@
+namespace Vlq
+{
+  using System;
+  using System.Collections.Generic;
+  using System.Linq;
+
+  public static class VarLenQuantity
+  {
+    public static ulong ToVlq(ulong integer)
+    {
+      var array = new byte[8];
+      var buffer = ToVlqCollection(integer)
+        .SkipWhile(b => b == 0)
+        .Reverse()
+        .ToArray();
+      Array.Copy(buffer, array, buffer.Length);
+      return BitConverter.ToUInt64(array, 0);
+    }
+
+    public static ulong FromVlq(ulong integer)
+    {
+      var collection = BitConverter.GetBytes(integer).Reverse();
+      return FromVlqCollection(collection);
+    }
+
+    public static IEnumerable<byte> ToVlqCollection(ulong integer)
+    {
+      if (integer > Math.Pow(2, 56))
+        throw new OverflowException("Integer exceeds max value.");
+
+      var index = 7;
+      var significantBitReached = false;
+      var mask = 0x7fUL << (index * 7);
+      while (index >= 0)
+      {
+        var buffer = (mask & integer);
+        if (buffer > 0 || significantBitReached)
+        {
+          significantBitReached = true;
+          buffer >>= index * 7;
+          if (index > 0)
+            buffer |= 0x80;
+          yield return (byte)buffer;
+        }
+        mask >>= 7;
+        index--;
+      }
+    }
+
+
+    public static ulong FromVlqCollection(IEnumerable<byte> vlq)
+    {
+      ulong integer = 0;
+      var significantBitReached = false;
+
+      using (var enumerator = vlq.GetEnumerator())
+      {
+        int index = 0;
+        while (enumerator.MoveNext())
+        {
+          var buffer = enumerator.Current;
+          if (buffer > 0 || significantBitReached)
+          {
+            significantBitReached = true;
+            integer <<= 7;
+            integer |= (buffer & 0x7fUL);
+          }
+
+          if (++index == 8 || (significantBitReached && (buffer & 0x80) != 0x80))
+            break;
+        }
+      }
+      return integer;
+    }
+
+    public static void Main()
+    {
+      var integers = new ulong[] { 0x7fUL << 7 * 7, 0x80, 0x2000, 0x3FFF, 0x4000, 0x200000, 0x1fffff };
+
+      foreach (var original in integers)
+      {
+        Console.WriteLine("Original: 0x{0:X}", original);
+
+        //collection
+        var seq = ToVlqCollection(original);
+        Console.WriteLine("Sequence: 0x{0}", seq.Select(b => b.ToString("X2")).Aggregate(string.Concat));
+
+        var decoded = FromVlqCollection(seq);
+        Console.WriteLine("Decoded: 0x{0:X}", decoded);
+
+        //ints
+        var encoded = ToVlq(original);
+        Console.WriteLine("Encoded: 0x{0:X}", encoded);
+
+        decoded = FromVlq(encoded);
+        Console.WriteLine("Decoded: 0x{0:X}", decoded);
+
+        Console.WriteLine();
+      }
+      Console.WriteLine("Press any key to continue...");
+      Console.ReadKey();
+    }
+  }
+}

Task/Variable-length-quantity/C-sharp/variable-length-quantity-2.cs

@@ -0,0 +1,43 @@
+Original: 0xFE000000000000
+Sequence: 0xFF80808080808000
+Decoded: 0xFE000000000000
+Encoded: 0xFF80808080808000
+Decoded: 0xFE000000000000
+
+Original: 0x80
+Sequence: 0x8100
+Decoded: 0x80
+Encoded: 0x8100
+Decoded: 0x80
+
+Original: 0x2000
+Sequence: 0xC000
+Decoded: 0x2000
+Encoded: 0xC000
+Decoded: 0x2000
+
+Original: 0x3FFF
+Sequence: 0xFF7F
+Decoded: 0x3FFF
+Encoded: 0xFF7F
+Decoded: 0x3FFF
+
+Original: 0x4000
+Sequence: 0x818000
+Decoded: 0x4000
+Encoded: 0x818000
+Decoded: 0x4000
+
+Original: 0x200000
+Sequence: 0x81808000
+Decoded: 0x200000
+Encoded: 0x81808000
+Decoded: 0x200000
+
+Original: 0x1FFFFF
+Sequence: 0xFFFF7F
+Decoded: 0x1FFFFF
+Encoded: 0xFFFF7F
+Decoded: 0x1FFFFF
+
+Press any key to continue...