ASTC optimizations (#845)

* ASTC optimizations

* Move code to Ryujinx.Common

* Support 3D textures

* Address feedback

* Remove ASTC logging

* Use stackalloc instead of a Buffer20 struct

* Code style and cleanup

* Respond to feedback

* Rearrange public/private property ordering

1 files changed, 31 insertions, 0 deletions

diff --git a/Ryujinx.Graphics.Texture/Astc/IntegerSequence.cs b/Ryujinx.Graphics.Texture/Astc/IntegerSequence.cs
new file mode 100644
index 00000000..367b6809
--- /dev/null
+++ b/Ryujinx.Graphics.Texture/Astc/IntegerSequence.cs
@@ -0,0 +1,31 @@
+using System;
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.Graphics.Texture.Astc
+{
+    [StructLayout(LayoutKind.Sequential, Size = IntegerEncoded.StructSize * Capacity + sizeof(int))]
+    internal struct IntegerSequence
+    {
+        private const int Capacity = 100;
+
+        private int _length;
+        private IntegerEncoded _start;
+
+        public Span<IntegerEncoded> List => MemoryMarshal.CreateSpan(ref _start, _length);
+
+        public void Reset() => _length = 0;
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Add(ref IntegerEncoded item)
+        {
+            Debug.Assert(_length < Capacity);
+
+            int oldLength = _length;
+            _length++;
+
+            List[oldLength] = item;
+        }
+    }
+}