c# - DllImport 或 LoadLibrary 以获得最佳性能

Question

我有外部 .DLL 文件，里面有快速汇编代码。在此 .DLL 文件中调用函数以获得最佳性能的最佳方式是什么？

Answer 1

你的 DLL 可能是 python 或 c++，不管怎样，按照下面的方式做。

这是您的 C++ DLL 文件。

标题:

extern "C" __declspec(dllexport) int MultiplyByTen(int numberToMultiply);

源代码文件

#include "DynamicDLLToCall.h"

int MultiplyByTen(int numberToMultiply)
{
    int returnValue = numberToMultiply * 10;
    return returnValue;
} 

看看下面的 C# 代码:

static class NativeMethods
{
    [DllImport("kernel32.dll")]
    public static extern IntPtr LoadLibrary(string dllToLoad);

    [DllImport("kernel32.dll")]
    public static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName);

    [DllImport("kernel32.dll")]
    public static extern bool FreeLibrary(IntPtr hModule);
}

class Program
{
    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    private delegate int MultiplyByTen(int numberToMultiply);

    static void Main(string[] args)
    {
            IntPtr pDll = NativeMethods.LoadLibrary(@"PathToYourDll.DLL");
            //oh dear, error handling here
            //if (pDll == IntPtr.Zero)

            IntPtr pAddressOfFunctionToCall = NativeMethods.GetProcAddress(pDll, "MultiplyByTen");
            //oh dear, error handling here
            //if(pAddressOfFunctionToCall == IntPtr.Zero)

            MultiplyByTen multiplyByTen = (MultiplyByTen)Marshal.GetDelegateForFunctionPointer(
                                                                                    pAddressOfFunctionToCall,
                                                                                    typeof(MultiplyByTen));

            int theResult = multiplyByTen(10);

            bool result = NativeMethods.FreeLibrary(pDll);
            //remaining code here

            Console.WriteLine(theResult);
    }
}