Hardware/PInvokeDelegateFactory.cs
author moel.mich
Thu, 12 Aug 2010 20:53:27 +0000
changeset 166 fa9dfbfc4145
child 167 b7cc9d09aefe
permissions -rw-r--r--
Changed the project files to Visual Studio 2010. Fixed some Code Analysis warnings.
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/*
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  Version: MPL 1.1/GPL 2.0/LGPL 2.1
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  The contents of this file are subject to the Mozilla Public License Version
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  1.1 (the "License"); you may not use this file except in compliance with
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  the License. You may obtain a copy of the License at
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  http://www.mozilla.org/MPL/
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  Software distributed under the License is distributed on an "AS IS" basis,
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  WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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  for the specific language governing rights and limitations under the License.
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  The Original Code is the Open Hardware Monitor code.
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  The Initial Developer of the Original Code is 
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  Michael Möller <m.moeller@gmx.ch>.
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  Portions created by the Initial Developer are Copyright (C) 2009-2010
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  the Initial Developer. All Rights Reserved.
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  Contributor(s):
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  Alternatively, the contents of this file may be used under the terms of
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  either the GNU General Public License Version 2 or later (the "GPL"), or
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  the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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  in which case the provisions of the GPL or the LGPL are applicable instead
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  of those above. If you wish to allow use of your version of this file only
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  under the terms of either the GPL or the LGPL, and not to allow others to
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  use your version of this file under the terms of the MPL, indicate your
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  decision by deleting the provisions above and replace them with the notice
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  and other provisions required by the GPL or the LGPL. If you do not delete
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  the provisions above, a recipient may use your version of this file under
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  the terms of any one of the MPL, the GPL or the LGPL.
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*/
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using System;
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using System.Collections.Generic;
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using System.Reflection;
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using System.Reflection.Emit;
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using System.Runtime.InteropServices;
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namespace OpenHardwareMonitor.Hardware {
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  internal sealed class PInvokeDelegateFactory {
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    private static AssemblyBuilder assemblyBuilder;
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    private static ModuleBuilder moduleBuilder;
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    private static IDictionary<DllImportAttribute, Type> wrapperTypes =
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      new Dictionary<DllImportAttribute, Type>();
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    static PInvokeDelegateFactory() {
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      AssemblyName assemblyName = new AssemblyName();
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      assemblyName.Name = "PInvokeDelegateFactoryInternalAssembly";
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      assemblyBuilder =
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        AppDomain.CurrentDomain.DefineDynamicAssembly(assemblyName,
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        AssemblyBuilderAccess.Run);
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      moduleBuilder = assemblyBuilder.DefineDynamicModule(
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        "PInvokeDelegateFactoryInternalModule");
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    }
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    private PInvokeDelegateFactory() { }
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    public static void CreateDelegate<T>(DllImportAttribute dllImportAttribute,
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      out T newDelegate) where T : class 
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    {
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      Type wrapperType;
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      wrapperTypes.TryGetValue(dllImportAttribute, out wrapperType);
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      if (wrapperType == null) {
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        wrapperType = CreateWrapperType(typeof(T), dllImportAttribute);
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        wrapperTypes.Add(dllImportAttribute, wrapperType);
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      }
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      newDelegate = Delegate.CreateDelegate(typeof(T), wrapperType,
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        dllImportAttribute.EntryPoint) as T;
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    }
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    private static Type CreateWrapperType(Type delegateType,
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      DllImportAttribute dllImportAttribute) {
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      TypeBuilder typeBuilder = moduleBuilder.DefineType(
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        "PInvokeDelegateFactoryInternalWrapperType" + wrapperTypes.Count);
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      MethodInfo methodInfo = delegateType.GetMethod("Invoke");
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      ParameterInfo[] parameterInfos = methodInfo.GetParameters();
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      int parameterCount = parameterInfos.GetLength(0);
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      Type[] parameterTypes = new Type[parameterCount];
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      for (int i = 0; i < parameterCount; i++)
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        parameterTypes[i] = parameterInfos[i].ParameterType;
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      MethodBuilder methodBuilder = typeBuilder.DefinePInvokeMethod(
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        dllImportAttribute.EntryPoint, dllImportAttribute.Value,
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        MethodAttributes.Public | MethodAttributes.Static |
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        MethodAttributes.PinvokeImpl, CallingConventions.Standard,
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        methodInfo.ReturnType, parameterTypes,
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        dllImportAttribute.CallingConvention,
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        dllImportAttribute.CharSet);
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      foreach (ParameterInfo parameterInfo in parameterInfos)
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        methodBuilder.DefineParameter(parameterInfo.Position + 1,
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          parameterInfo.Attributes, parameterInfo.Name);
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      if (dllImportAttribute.PreserveSig)
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        methodBuilder.SetImplementationFlags(MethodImplAttributes.PreserveSig);
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      return typeBuilder.CreateType();
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    }
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  }
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}