1  using System;
 2  using System.Runtime.CompilerServices;
 3  using System.Runtime.InteropServices;
 4  
 5  namespace Ryujinx.Graphics.Texture.Astc
 6  {
 7      [StructLayout(LayoutKind.Sequential)]
 8      struct AstcPixel
 9      {
10          internal const int StructSize = 12;
11  
12          public short A;
13          public short R;
14          public short G;
15          public short B;
16  
17          private uint _bitDepthInt;
18  
19          private Span<byte> BitDepth => MemoryMarshal.CreateSpan(ref Unsafe.As<uint, byte>(ref _bitDepthInt), 4);
20          private Span<short> Components => MemoryMarshal.CreateSpan(ref A, 4);
21  
22          public AstcPixel(short a, short r, short g, short b)
23          {
24              A = a;
25              R = r;
26              G = g;
27              B = b;
28  
29              _bitDepthInt = 0x08080808;
30          }
31  
32          public void ClampByte()
33          {
34              R = Math.Min(Math.Max(R, (short)0), (short)255);
35              G = Math.Min(Math.Max(G, (short)0), (short)255);
36              B = Math.Min(Math.Max(B, (short)0), (short)255);
37              A = Math.Min(Math.Max(A, (short)0), (short)255);
38          }
39  
40          public short GetComponent(int index)
41          {
42              return Components[index];
43          }
44  
45          public void SetComponent(int index, int value)
46          {
47              Components[index] = (short)value;
48          }
49  
50          public readonly int Pack()
51          {
52              return A << 24 |
53                     B << 16 |
54                     G << 8 |
55                     R << 0;
56          }
57  
58          // Adds more precision to the blue channel as described
59          // in C.2.14
60          public static AstcPixel BlueContract(int a, int r, int g, int b)
61          {
62              return new AstcPixel((short)(a),
63                                   (short)((r + b) >> 1),
64                                   (short)((g + b) >> 1),
65                                   (short)(b));
66          }
67      }
68  }