Copy arrays of primitive values using System.Buffers.MemoryCopy (#1440)

src/AST/TypeExtensions.cs

@@ -435,5 +435,10 @@
 
             return declaration.TranslationUnit.Module;
         }
+
+        public static long GetSizeInBytes(this ArrayType array)
+        {
+            return array.Size * (array.ElementSize / 8);
+        }
     }
 }

src/Generator/Generators/CSharp/CSharpMarshal.cs

@@ -80,12 +80,23 @@ namespace CppSharp.Generators.CSharp
                     supportBefore.WriteLine($"if ({Context.ReturnVarName} != null)");
                     supportBefore.WriteOpenBraceAndIndent();
                     supportBefore.WriteLine($"{value} = new {arrayType}[{array.Size}];");
+
+                    if (CheckIfArrayCanBeCopiedUsingMemoryCopy(array))
+                    {
+                        var arraySizeInBytes = array.GetSizeInBytes();
+                        var fixedArray = Generator.GeneratedIdentifier($"{value}fixed");
+                        supportBefore.WriteLine($"fixed (void* {fixedArray} = {value})");
+                        supportBefore.WriteLineIndent(
+                            $"System.Buffer.MemoryCopy((void*){Context.ReturnVarName}, {fixedArray}, {arraySizeInBytes}, {arraySizeInBytes});");
+                    }
+                    else { 
                         supportBefore.WriteLine($"for (int i = 0; i < {array.Size}; i++)");
                         if (array.Type.IsPointerToPrimitiveType(PrimitiveType.Void))
                             supportBefore.WriteLineIndent($@"{value}[i] = new global::System.IntPtr({
                                 Context.ReturnVarName}[i]);");
                         else
                         {
+                          
                             var finalArrayType = arrayType.GetPointee() ?? arrayType;
                             Class @class;
                             if ((finalArrayType.TryGetClass(out @class)) && @class.IsRefType)
@@ -114,6 +125,7 @@ namespace CppSharp.Generators.CSharp
                                         Context.ReturnVarName}[i];");
                             }
                         }
+                    }
                     supportBefore.UnindentAndWriteCloseBrace();
                     Context.Return.Write(value);
                     break;
@@ -428,6 +440,12 @@ namespace CppSharp.Generators.CSharp
             Context.Return.Write(intermediateArray);
         }
 
+        public bool CheckIfArrayCanBeCopiedUsingMemoryCopy(ArrayType array)
+        {
+            return array.Type.IsPrimitiveType(out var primitive) &&
+                (!Context.Context.Options.MarshalCharAsManagedChar || primitive != PrimitiveType.Char);
+        }
+
         private readonly CSharpTypePrinter typePrinter;
     }