1 files changed, 134 insertions, 0 deletions
diff --git a/Ryujinx.Graphics.Nvdec/VDec/VpxRangeEncoder.cs b/Ryujinx.Graphics.Nvdec/VDec/VpxRangeEncoder.cs
new file mode 100644
index 00000000..c854c9d9
--- /dev/null
+++ b/Ryujinx.Graphics.Nvdec/VDec/VpxRangeEncoder.cs
@@ -0,0 +1,134 @@
+using System.IO;
+
+namespace Ryujinx.Graphics.VDec
+{
+    class VpxRangeEncoder
+    {
+        private const int HalfProbability = 128;
+
+        private static readonly int[] NormLut = new int[]
+        {
+            0, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
+            3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+        };
+
+        private Stream _baseStream;
+
+        private uint _lowValue;
+        private uint _range;
+        private int  _count;
+
+        public VpxRangeEncoder(Stream baseStream)
+        {
+            _baseStream = baseStream;
+
+            _range = 0xff;
+            _count = -24;
+
+            Write(false);
+        }
+
+        public void WriteByte(byte value)
+        {
+            Write(value, 8);
+        }
+
+        public void Write(int value, int valueSize)
+        {
+            for (int bit = valueSize - 1; bit >= 0; bit--)
+            {
+                Write(((value >> bit) & 1) != 0);
+            }
+        }
+
+        public void Write(bool bit)
+        {
+            Write(bit, HalfProbability);
+        }
+
+        public void Write(bool bit, int probability)
+        {
+            uint range = _range;
+
+            uint split = 1 + (((range - 1) * (uint)probability) >> 8);
+
+            range = split;
+
+            if (bit)
+            {
+                _lowValue += split;
+                range      = _range - split;
+            }
+
+            int shift = NormLut[range];
+
+            range  <<= shift;
+            _count  += shift;
+
+            if (_count >= 0)
+            {
+                int offset = shift - _count;
+
+                if (((_lowValue << (offset - 1)) >> 31) != 0)
+                {
+                    long currentPos = _baseStream.Position;
+
+                    _baseStream.Seek(-1, SeekOrigin.Current);
+
+                    while (_baseStream.Position >= 0 && PeekByte() == 0xff)
+                    {
+                        _baseStream.WriteByte(0);
+
+                        _baseStream.Seek(-2, SeekOrigin.Current);
+                    }
+
+                    _baseStream.WriteByte((byte)(PeekByte() + 1));
+
+                    _baseStream.Seek(currentPos, SeekOrigin.Begin);
+                }
+
+                _baseStream.WriteByte((byte)(_lowValue >> (24 - offset)));
+
+                _lowValue <<= offset;
+                shift       = _count;
+                _lowValue  &= 0xffffff;
+                _count     -= 8;
+            }
+
+            _lowValue <<= shift;
+
+            _range = range;
+        }
+
+        private byte PeekByte()
+        {
+            byte value = (byte)_baseStream.ReadByte();
+
+            _baseStream.Seek(-1, SeekOrigin.Current);
+
+            return value;
+        }
+
+        public void End()
+        {
+            for (int index = 0; index < 32; index++)
+            {
+                Write(false);
+            }
+        }
+    }
+}
+\ No newline at end of file