1 files changed, 75 insertions, 0 deletions
diff --git a/Ryujinx.Graphics.Nvdec/VDec/BitStreamWriter.cs b/Ryujinx.Graphics.Nvdec/VDec/BitStreamWriter.cs
new file mode 100644
index 00000000..db2d39e5
--- /dev/null
+++ b/Ryujinx.Graphics.Nvdec/VDec/BitStreamWriter.cs
@@ -0,0 +1,75 @@
+using System.IO;
+
+namespace Ryujinx.Graphics.VDec
+{
+    class BitStreamWriter
+    {
+        private const int BufferSize = 8;
+
+        private Stream _baseStream;
+
+        private int _buffer;
+        private int _bufferPos;
+
+        public BitStreamWriter(Stream baseStream)
+        {
+            _baseStream = baseStream;
+        }
+
+        public void WriteBit(bool value)
+        {
+            WriteBits(value ? 1 : 0, 1);
+        }
+
+        public void WriteBits(int value, int valueSize)
+        {
+            int valuePos = 0;
+
+            int remaining = valueSize;
+
+            while (remaining > 0)
+            {
+                int copySize = remaining;
+
+                int free = GetFreeBufferBits();
+
+                if (copySize > free)
+                {
+                    copySize = free;
+                }
+
+                int mask = (1 << copySize) - 1;
+
+                int srcShift = (valueSize  - valuePos)  - copySize;
+                int dstShift = (BufferSize - _bufferPos) - copySize;
+
+                _buffer |= ((value >> srcShift) & mask) << dstShift;
+
+                valuePos   += copySize;
+                _bufferPos += copySize;
+                remaining  -= copySize;
+            }
+        }
+
+        private int GetFreeBufferBits()
+        {
+            if (_bufferPos == BufferSize)
+            {
+                Flush();
+            }
+
+            return BufferSize - _bufferPos;
+        }
+
+        public void Flush()
+        {
+            if (_bufferPos != 0)
+            {
+                _baseStream.WriteByte((byte)_buffer);
+
+                _buffer    = 0;
+                _bufferPos = 0;
+            }
+        }
+    }
+}
+\ No newline at end of file