NVDEC implementation using FFmpeg (#443)

* Initial nvdec implementation using FFmpeg

* Fix swapped channels on the video decoder and the G8R8 texture format

* Fix texture samplers not being set properly (regression)

* Rebased

* Remove unused code introduced on the rebase

* Add support for RGBA8 output format on the video image composer

* Correct spacing

* Some fixes for rebase and other tweaks

* Allow size mismatch on frame copy

* Get rid of GetHostAddress calls on VDec

1 files changed, 75 insertions, 0 deletions

diff --git a/Ryujinx.Graphics/VDec/BitStreamWriter.cs b/Ryujinx.Graphics/VDec/BitStreamWriter.cs
new file mode 100644
index 00000000..44d07906
--- /dev/null
+++ b/Ryujinx.Graphics/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)
+        {
+            this.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