use UnmanagedCallersOnly for delegates

src/ARMeilleure/Instructions/MathHelper.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace ARMeilleure.Instructions
+{
+    static class MathHelper
+    {
+        [UnmanagedCallersOnly]
+        public static double Abs(double value)
+        {
+            return Math.Abs(value);
+        }
+
+        [UnmanagedCallersOnly]
+        public static double Ceiling(double value)
+        {
+            return Math.Ceiling(value);
+        }
+
+        [UnmanagedCallersOnly]
+        public static double Floor(double value)
+        {
+            return Math.Floor(value);
+        }
+
+        [UnmanagedCallersOnly]
+        public static double Round(double value, int mode)
+        {
+            return Math.Round(value, (MidpointRounding)mode);
+        }
+
+        [UnmanagedCallersOnly]
+        public static double Truncate(double value)
+        {
+            return Math.Truncate(value);
+        }
+    }
+
+    static class MathHelperF
+    {
+        [UnmanagedCallersOnly]
+        public static float Abs(float value)
+        {
+            return MathF.Abs(value);
+        }
+
+        [UnmanagedCallersOnly]
+        public static float Ceiling(float value)
+        {
+            return MathF.Ceiling(value);
+        }
+
+        [UnmanagedCallersOnly]
+        public static float Floor(float value)
+        {
+            return MathF.Floor(value);
+        }
+
+        [UnmanagedCallersOnly]
+        public static float Round(float value, int mode)
+        {
+            return MathF.Round(value, (MidpointRounding)mode);
+        }
+
+        [UnmanagedCallersOnly]
+        public static float Truncate(float value)
+        {
+            return MathF.Truncate(value);
+        }
+    }
+}