Re-add NVDEC project (not integrated)

Ryujinx.Graphics.Nvdec/VDec/VpxBitStreamWriter.cs

@@ -0,0 +1,38 @@
+using System.IO;
+
+namespace Ryujinx.Graphics.VDec
+{
+    class VpxBitStreamWriter : BitStreamWriter
+    {
+        public VpxBitStreamWriter(Stream baseStream) : base(baseStream) { }
+
+        public void WriteU(int value, int valueSize)
+        {
+            WriteBits(value, valueSize);
+        }
+
+        public void WriteS(int value, int valueSize)
+        {
+            bool sign = value < 0;
+
+            if (sign)
+            {
+                value = -value;
+            }
+
+            WriteBits((value << 1) | (sign ? 1 : 0), valueSize + 1);
+        }
+
+        public void WriteDeltaQ(int value)
+        {
+            bool deltaCoded = value != 0;
+
+            WriteBit(deltaCoded);
+
+            if (deltaCoded)
+            {
+                WriteBits(value, 4);
+            }
+        }
+    }
+}