add new struct definitions

Il2CppInspector.Common/Next/Metadata/Il2CppMetadataUsage.cs

@@ -0,0 +1,64 @@
+using System.Diagnostics;
+using VersionedSerialization;
+
+namespace Il2CppInspector.Next.Metadata;
+
+using VersionedSerialization.Attributes;
+using EncodedMethodIndex = uint;
+
+[VersionedStruct]
+public partial struct Il2CppMetadataUsage
+{
+    private const uint TypeMask = 0b111u << 29;
+    private const uint InflatedMask = 0b1;
+    private const uint IndexMask = ~(TypeMask | InflatedMask);
+
+    public readonly Il2CppMetadataUsageType Type => (Il2CppMetadataUsageType)((EncodedValue & TypeMask) >> 29);
+    public readonly uint Index => (EncodedValue & IndexMask) >> 1;
+    public readonly bool Inflated => (EncodedValue & InflatedMask) == 1;
+
+    public EncodedMethodIndex EncodedValue;
+
+    public static Il2CppMetadataUsage FromValue(in StructVersion version, uint encodedValue)
+    {
+        if (version >= MetadataVersions.V270)
+        {
+            return new Il2CppMetadataUsage
+            {
+                EncodedValue = encodedValue
+            };
+        }
+
+        if (version >= MetadataVersions.V190)
+        {
+            // Below v27 we need to fake the 'inflated' flag, so shift the value by one
+
+            var type = (encodedValue & TypeMask) >> 29;
+            var value = encodedValue & (IndexMask | 1);
+            Debug.Assert((value & 0x10000000) == 0);
+
+            return new Il2CppMetadataUsage
+            {
+                EncodedValue = (type << 29) | (value << 1)
+            };
+        }
+
+        /* These encoded indices appear only in vtables, and are decoded by IsGenericMethodIndex/GetDecodedMethodIndex */
+        var methodType = (encodedValue >> 31) != 0
+            ? Il2CppMetadataUsageType.MethodRef 
+            : Il2CppMetadataUsageType.MethodDef;
+
+        var index = encodedValue & 0x7FFFFFFF;
+        Debug.Assert((index & 0x60000000) == 0);
+
+        return new Il2CppMetadataUsage
+        {
+            EncodedValue = ((uint)methodType << 29) | (index << 1)
+        };
+    }
+
+    public readonly override string ToString()
+    {
+        return $"{Type} @ 0x{Index:X}";
+    }
+}