[英]Passing Data in and out of a DLL from C#
I am attempting to create a C# program that can pass data into a C/C++ DLL, store the data, and complete calculations on it. 我正在尝试创建一个C#程序,该程序可以将数据传递到C / C ++ DLL中,存储数据并完成对它的计算。 The result would then be returned to the C# program.
然后将结果返回到C#程序。 The reason for not using C# for the calculations is that I am planning to accelerate it with CUDA.
不使用C#进行计算的原因是我计划使用CUDA加速它。
I currently declaring a byte array in C#, and passing that as an argument to the DLL to send data. 我目前在C#中声明一个字节数组,并将其作为参数传递给DLL以发送数据。
I then declare a byte array of the same size in C# and pass it as an argument to receive the data. 然后,我在C#中声明一个大小相同的字节数组,并将其作为参数传递以接收数据。 The DLL should then write the results into that memory.
DLL然后应将结果写入该内存。
When I run the program, the correct numbers get printed to the screen. 当我运行程序时,正确的数字会显示在屏幕上。 (As I am writing 1,2,3... to the array twice, the addition of these is 2,4,6...) "The cat chased the mouse" is then printed.
(当我将1,2,3 ...两次写入数组时,它们的加法是2,4,6...。)然后打印“猫追了老鼠”。 When I press a key, "The mouse chased the cat" is displayed, and the program crashes before it exits displaying a vshost32.exe stopped working error.
当我按一个键时,将显示“鼠标追逐了猫”,并且该程序在退出前崩溃,并显示vshost32.exe停止工作错误。 I was able to solve this error from this question .
我能够从这个问题解决这个错误。
Now when I attempt to run the EXE directly from windows explorer, I get the number 36 printed as the first step, but then I get the following error on the compute function call: 现在,当我尝试直接从Windows资源管理器运行EXE时,第一步得到的数字为36,但是在计算函数调用时出现以下错误:
"Unhanded exception: System.AccessViolationException Attempted to read or write protected memory. This is often an indication that other memory is corrupt"
“未处理的异常:System.AccessViolationException尝试读取或写入受保护的内存。这通常表明其他内存已损坏”
I know the DLL loaded correctly because the init function returned the correct number. 我知道DLL已正确加载,因为init函数返回了正确的数字。 I am not sure why it would only be crashing when I am running it as an EXE and not in the debugger.
我不确定为什么仅当我将其作为EXE而不是在调试器中运行时才会崩溃。 What could be causing this?
是什么原因造成的?
Is there a different way I should be handling the memory exchange between the DLL and the C# program? 我应该以其他方式处理DLL和C#程序之间的内存交换吗? My goal is to avoid copying it using a Marshal Copy as I need this to be high performance.
我的目标是避免使用元帅副本来复制它,因为我需要这样做才能提高性能。 The end goal would be the DLL copying the memory to or from the GPU and the GPU doing the calculations, so I see no reason to have it copied a 2nd time in the DLL before going to the GPU.
最终目标是DLL将内存复制到GPU或从GPU复制内存,然后GPU进行计算,因此我认为没有理由在进入GPU之前将其第二次复制到DLL中。
C++ DLL Code (written as C code) C ++ DLL代码(编写为C代码)
#include "stdafx.h"
#include "stdlib.h"
const int CONSTANT = 3;
char** items;
int itemCount = 0;
int xcnt = -1;
int ycnt = -1;
extern "C" int __declspec(dllexport) __stdcall init(int itemcount_local, int xcnt_local, int ycnt_local){
itemCount = itemcount_local;
xcnt = xcnt_local;
ycnt = ycnt_local;
items = (char**)malloc(itemCount);
if (items == NULL){
return -1;
}
for (int i = 0; i < itemCount; i++){
items[i] = (char*)malloc(CONSTANT*xcnt*ycnt);
if (items[i] == NULL){
return -1;
}
for (int d = 0; d < CONSTANT*xcnt*ycnt; d++){
items[i][d] = 0;
}
}
return CONSTANT*xcnt*ycnt;
}
//frees the memory created in init
extern "C" void __declspec(dllexport) __stdcall cleanup(){
for (int i = 0; i < itemCount; i++){
free(items[i]);
}
free(items);
return;
}
extern "C" void __declspec(dllexport) __stdcall loadItem(int index, char* data){
memcpy(items[index], data, CONSTANT*xcnt*ycnt);
return;
}
//fills the buffer with the computed result. Buffer needs to be the size of CONSTANT*xcnt*ycnt
extern "C" void __declspec(dllexport) __stdcall compute(char* buffer){
for (int x = 0; x < CONSTANT*xcnt*ycnt; x++){
int sum = 0;
for (int i = 0; i < itemCount; i++){
sum += items[i][x];
}
if (sum > 255){ //saturate at 255
buffer[x] = 255;
}
else {
buffer[x] = sum;
}
}
return;
}
C# code C#代码
class Program
{
[DllImport("DllTest1.dll", CallingConvention=CallingConvention.StdCall, SetLastError = true, CharSet = CharSet.Ansi)]
public static extern int init(int imagecount_local, int xres_local, int yres_local);
[DllImport("DllTest1.dll", CallingConvention=CallingConvention.StdCall, SetLastError = true, CharSet = CharSet.Ansi)]
public static extern void cleanup();
[DllImport("DllTest1.dll", CallingConvention=CallingConvention.StdCall, SetLastError = true, CharSet = CharSet.Ansi)]
public static extern void loadItem(int index, byte[] data);
[DllImport("DllTest1.dll", CallingConvention=CallingConvention.StdCall, SetLastError = true, CharSet = CharSet.Ansi)]
public static extern void compute(byte[] buffer);
static void Main(string[] args)
{
int x = 4, y = 3;
int total = x * y * 3;
Console.WriteLine(init(5, x, y));
byte[] a = new byte[total];
compute(a);
for (int i = 0; i < total; i++)
{
Console.WriteLine(a[i]);
}
byte[] b = new byte[total];
for (int i = 0; i < total; i++)
{
b[i] = (byte)i;
}
loadItem(0, b);
loadItem(1, b);
compute(a);
for (int i = 0; i < total; i++)
{
Console.WriteLine(a[i]);
}
//cleanup();
Console.WriteLine("The cat chased the mouse");
Console.ReadKey();
Console.WriteLine("The mouse chased the cat");
return;
}
}
I was able to solve the problem. 我能够解决问题。 The line
线
items = (char**)malloc(itemCount);
should have been 本来应该
items = (char**)malloc(itemCount*sizeof(char*));
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