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这是我的第一个stackoverflow帖子。我一直在这个问题上困扰数日。我尝试将一个C DLL的usbi2cio.dll导入到一个基于C#的项目中。我浏览了网站中的大部分类似帖子,但仍然无法解决我的问题,因为我的情况可能有点不同。将C dll函数导入C#
因此,这里是API的原始定义及相关结构作为参数:
LONG _stdcall DAPI_ReadI2c(HANDLE hDevInstance, I2C_TRANS * TransI2C);
typedef struct _I2C_TRANS {
BYTE byTransType;
BYTE bySlvDevAddr;
WORD wMemoryAddr;
WORD wCount;
BYTE Data[256];
}I2C_TRANS, *PI2C_TRANS;
//In my C# code, I did the translation like this:
[StructLayoutAttribute(LayoutKind.Sequential), Serializable]
public struct I2C_TRANS
{
public byte byTransType;
public byte bySlvDevAddr;
public ushort wMemoryAddr;
public ushort wCount;
[MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 256, ArraySubType = UnmanagedType.I1)]
public byte[] Data;
public I2C_TRANS(int size)
{
Data = new byte[size];
this.byTransType = 0x00;
this.bySlvDevAddr = 0x00;
this.wMemoryAddr = 0;
this.wCount = 0;
}
};
public I2C_TRANS TransI2C = new I2C_TRANS(256);
public IntPtr[] hDevice = new IntPtr[DAPI_MAX_DEVICES];
...
TransI2C.byTransType = byTransType;
TransI2C.bySlvDevAddr = bySlvDevAddr;
TransI2C.wMemoryAddr = wMemoryAddr;
TransI2C.wCount = wCount;// no larger than 64
...
if((hDevice[0] = DAPI_OpenDeviceInstance(devName, 0)) != INVALID_HANDLE_VALUE)
//the returned lReadCnt should be equal to wCount.
Public int lReadCnt = DAPI_ReadI2c(hDevice[0], ref TransI2C);
出于某种原因,在读I2C交易结构不能很好地通过,其结果是,该函数返回0值没有错误(我期望与wCount相同的值)。对于其他类似的API和结构,它运行良好。那么这个问题可能是什么原因呢?
//Here is the P/Invoke declaration:
[DllImportAttribute("UsbI2cIo.dll", EntryPoint = "DAPI_ReadI2c", CallingConvention = CallingConvention.StdCall)]
public static extern int DAPI_ReadI2c(IntPtr hDevInstance, ref I2C_TRANS TransI2C);
什么是P/Invoke声明?另外,试着让C#结构变成一个类而不是一个结构,并从P/Invoke中移除'ref'。 – 2013-04-08 18:45:16
pinvoke上的圣经是亚当Nathans - .NET和COM:完整的互操作性指南 – pm100 2013-04-08 18:59:54
棘手的是另一个API是:“[DllImportAttribute(”UsbI2cIo.dll“,EntryPoint =”DAPI_GetDeviceInfo“,CallingConvention = CallingConvention.StdCall) ] public static extern byte DAPI_GetDeviceInfo([MarshalAsAttribute(UnmanagedType.LPStr)] StringBuilder lpsDevName,ref LPDEVINFO lpDevInfo);“它具有类似的结构格式和传递参数,但读/写部分运行缓慢。 – Hao 2013-04-08 19:03:36