Re-add NVDEC project (not integrated)

Ryujinx.Graphics.Nvdec/VDec/H264BitStreamWriter.cs

@@ -0,0 +1,79 @@
+using System.IO;
+
+namespace Ryujinx.Graphics.VDec
+{
+    class H264BitStreamWriter : BitStreamWriter
+    {
+        public H264BitStreamWriter(Stream baseStream) : base(baseStream) { }
+
+        public void WriteU(int value, int valueSize)
+        {
+            WriteBits(value, valueSize);
+        }
+
+        public void WriteSe(int value)
+        {
+            WriteExpGolombCodedInt(value);
+        }
+
+        public void WriteUe(int value)
+        {
+            WriteExpGolombCodedUInt((uint)value);
+        }
+
+        public void End()
+        {
+            WriteBit(true);
+
+            Flush();
+        }
+
+        private void WriteExpGolombCodedInt(int value)
+        {
+            int sign = value <= 0 ? 0 : 1;
+
+            if (value < 0)
+            {
+                value = -value;
+            }
+
+            value = (value << 1) - sign;
+
+            WriteExpGolombCodedUInt((uint)value);
+        }
+
+        private void WriteExpGolombCodedUInt(uint value)
+        {
+            int size = 32 - CountLeadingZeros((int)value + 1);
+
+            WriteBits(1, size);
+
+            value -= (1u << (size - 1)) - 1;
+
+            WriteBits((int)value, size - 1);
+        }
+
+        private static readonly byte[] ClzNibbleTbl = { 4, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0 };
+
+        private static int CountLeadingZeros(int value)
+        {
+            if (value == 0)
+            {
+                return 32;
+            }
+
+            int nibbleIdx = 32;
+            int preCount, count = 0;
+
+            do
+            {
+                nibbleIdx -= 4;
+                preCount = ClzNibbleTbl[(value >> nibbleIdx) & 0b1111];
+                count += preCount;
+            }
+            while (preCount == 4);
+
+            return count;
+        }
+    }
+}