我试图写一个必须实现以下功能插件DLL:如何编组指向指向从托管代码到非托管代码的结构的指针数组的指针?
int GetFunctionTable(FuncDescStruct **ppFunctionTable);
所以在C#我的插件代码声明如下:
public static unsafe int GetFunctionTable(IntPtr functionTablePtr);
这个函数会被调用,并有望填补functionTablePtr,指针指向描述一组回调函数的结构数组。
在普通的C/C++,它看起来是这样的:
// declare func table
// VExampleF1, VExampleF2 - are function pointers
FuncDescStruct funcTable[] = {
"ExampleF1", { VExampleF1, 0, 0, 0, 0, NULL }, //filling descriptions.
"ExampleF2", { VExampleF2, 1, 0, 1, 0, NULL }
};
int GetFunctionTable(FuncDescStruct **ppFunctionTable)
{
*ppFunctionTable = funcTable; // how to do this correctly in C#?
// must return the number of functions in the table
return funcTableSize;
}
我试图做到以下几点:
static unsafe FunctionTag[] funcTable;
static List<IntPtr> allocatedMemory;
public static unsafe int GetFunctionTable(IntPtr functionTablePtr)
{
//create just one test callback description
funcTable = new FunctionTag[1];
funcTable[0].Name = "VExampleF1";
funcTable[0].Description.Function = VExampleF1;
funcTable[0].Description.ArrayQty = 0;
funcTable[0].Description.FloatQty = 0;
funcTable[0].Description.StringQty = 0;
funcTable[0].Description.DefaultQty = 0;
funcTable[0].Description.DefaultValues = null;
// saving allocated memory for further cleanup
allocatedMemory = new List<IntPtr>();
int intPtrSize = Marshal.SizeOf(typeof(IntPtr));
IntPtr nativeArray = Marshal.AllocHGlobal(intPtrSize * funcTable.Length);
for (int i = 0; i < funcTable.Length; i++)
{
IntPtr nativeFD = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(FunctionTag)));
allocatedMemory.Add(nativeFD);
Marshal.StructureToPtr(funcTable[i], nativeFD, false);
Marshal.WriteIntPtr(nativeArray, i * intPtrSize, nativeFD);
}
Marshal.WriteIntPtr(functionTablePtr, nativeArray);
return funcTable.Length;
}
这样的代码不工作,问题是如何发送一个指向托管结构数组的指针,供非托管代码使用?我应该往哪个方向走?