英創(chuàng)信息技術(shù)嵌入式系統(tǒng)設(shè)備驅(qū)動接口的C#編程

英創(chuàng)ARM9系列嵌入式主板，均預(yù)裝了WinCE 5.0、WinCE 6.0操作系統(tǒng)，用戶可使用標(biāo)準(zhǔn)的C/C++或C#進(jìn)行應(yīng)用程序的開發(fā)。英創(chuàng)的嵌入式板卡一大特色就是提供了豐富的通訊接口，并實現(xiàn)了相應(yīng)的驅(qū)動程序，用戶只需直接調(diào)用相應(yīng)的接口函數(shù)即可實現(xiàn)。

在使用C#進(jìn)行應(yīng)用程序開發(fā)時，由于C#無法使用C++的靜態(tài)庫函數(shù)，對于一些流式驅(qū)動設(shè)備，比如ISA，GPIO，WDT，CAN，SPI，IRQ等，沒有封裝好的庫函數(shù)可操作，如果希望控制它們，一種辦法是使用C編寫com組件，在com組件中調(diào)用英創(chuàng)提供的相應(yīng)主板SDK包里的靜態(tài)庫函數(shù);另一種方法是直接調(diào)用API函數(shù)來訪問設(shè)備驅(qū)動。

對于大多數(shù)的流式驅(qū)動設(shè)備，應(yīng)用程序使用的一般過程：
1、通過CreatFile打開設(shè)備，獲得設(shè)備句柄。
2、使用ReadFile讀取數(shù)據(jù)，使用WriteFile發(fā)送數(shù)據(jù)，以及使用DeviceIoControl對設(shè)備驅(qū)動進(jìn)行設(shè)置、讀寫等操作。
3、使用完畢，用CloseHandle關(guān)閉設(shè)備。

在一般情況下，設(shè)備的專用功能都是通過DeviceIoControl來實現(xiàn)的，因此如何通過C#編程來操作DeviceIoControl尤為重要。本文以英創(chuàng)ARM9嵌入式主板EM9170為例，介紹如何使用DeviceIoControl來操作主板的ISA接口進(jìn)行讀寫。GPIO，WDT，CAN，SPI，IRQ等其他流式設(shè)備的操作請參看英創(chuàng)開發(fā)光盤內(nèi)提供的相關(guān)例程。

1、DeviceIoControl函數(shù)的定義
在wince中核心庫為coredll.dll，相當(dāng)于window的kernel32.dll和user32.dll。要調(diào)用核心庫，首先需要在代碼中添加引用：

using System.Runtime.InteropServices;

在c#中DeviceIoControl及CreatFiles，CloseHandle函數(shù)聲明，及相關(guān)變量定義方法如下（該寫法并不固定）。

[DllImport('coredll.dll', EntryPoint = 'CreateFile', CharSet = CharSet.Unicode)]
private static extern int CreateFile(String lpFileName,
uint dwDesiredAccess,
uint dwShareMode,
int lpSecurityAttributes,
int dwCreationDisposition,
int dwFlagsAndAttributes,
int hTemplateFile);

[DllImport('coredll.dll', EntryPoint = 'CloseHandle')]
private static extern int CloseHandle(int hObject);

[DllImport('coredll.dll', EntryPoint = 'DeviceIoControl')]
private static extern bool DeviceIoControl(int hDevice,
uint dwIoControlCode,
byte[] lpInBuf,
uint nInBufSize,
byte[] lpOutBuf,
uint nOutBufSize,
ref uint lpBytesReturned,
uint lpOverlapped);

DeviceIoControl函數(shù)參數(shù)分析：

在C#調(diào)用外部dll時，可以用uint來對應(yīng)DWORD，用ref uint來對應(yīng)LPDWORD，用IntPtr來對應(yīng)各種指針，更通用的，可以直接使用byte[]來對應(yīng)各種指針。

2、DeviceIoControl函數(shù)的操作實例
以英創(chuàng)嵌入式主板EM9170的ISA操作為例，以下代碼包括了CreatFile需要的參數(shù)定義，ISA操作的IOCTL定義，和ISA的DeviceIoControl操作傳入?yún)?shù)結(jié)構(gòu)體的定義，和封裝DeviceIoControl的兩個ISA函數(shù)定義。

主函數(shù)操作程序打開ISA設(shè)備，并操作ISA輸出輸入，最后關(guān)閉設(shè)備。

private const uint GENERIC_READ = 0x80000000;
private const uint GENERIC_WRITE = 0x40000000;
private const uint FILE_SHARE_READ = 0x00000001;
private const uint FILE_SHARE_WRITE = 0x00000002;
private const int OPEN_EXISTING = 3;
private const int FILE_FLAG_RANDOM_ACCESS = 0x10000000;
//------------------------bsp_drivers----------------------------------
//winioctl
private const uint FILE_DEVICE_BUS_EXTENDER = 0x0000002a;
private const uint METHOD_BUFFERED = 0;
private const uint FILE_ANY_ACCESS = 0;
// ISA IO Control Codes
private const uint ISA_IOCTL_READ_WRITE = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3910 << 2) | (METHOD_BUFFERED);
private const uint ISA_IOCTL_BUS_RESET = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3911 << 2) | (METHOD_BUFFERED);
//------------------------bsp_drivers_end------------------------------
[StructLayout(LayoutKind.Explicit, Size = 16)]
public struct ISA_BUS_ACCESS
{
[FieldOffset(0)]public uint dwCmd; // = 0: Read, = 1: Write
[FieldOffset(4)]public uint dwSeg; // = 0: ISA_CS0, = 1: ISA_CS1
[FieldOffset(8)]public uint dwOffset;
[FieldOffset(12)]public uint dwValue; // only lower byte valid
}
public static int OpenISA_DIO(String DevName)
{
int handle;
handle = CreateFile(DevName,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE, // sharing mode
0, // security attributes (ignored)
OPEN_EXISTING, // creation disposition
FILE_FLAG_RANDOM_ACCESS, // flags/attributes
0);
return handle;
}
public static bool CloseISA_DIO(int hISA_DIO)
{
if (hISA_DIO != 0)
{
if (CloseHandle(hISA_DIO) != 0)
{
return false;
}
}
return true;
}
public static bool ISA_Read(int hISA_DIO, int nSeg, uint nOffset, ref byte pRdValue)
{
ISA_BUS_ACCESS isabus;
uint lpBytesReturned = 0;
isabus.dwCmd = 0;
isabus.dwSeg = (uint)nSeg;
isabus.dwOffset = nOffset;
isabus.dwValue = 0;
int size = Marshal.SizeOf(typeof(ISA_BUS_ACCESS));
byte[] lpIntBuf = new byte[size];
IntPtr buffer = Marshal.AllocHGlobal(size);
try
{
Marshal.StructureToPtr(isabus, buffer, false);
Marshal.Copy(buffer, lpIntBuf, 0, size);
}
finally
{
Marshal.FreeHGlobal(buffer);
}
byte[] lpOutBuf = new byte[sizeof(byte)];
if (!DeviceIoControl(hISA_DIO, // file handle to the driver
ISA_IOCTL_READ_WRITE, // I/O control code
lpIntBuf, // in buffer
(uint)size, // in buffer size
lpOutBuf, // out buffer
sizeof(byte), // out buffer size
ref lpBytesReturned, // pointer to number of bytes returned
0)) // ignored (=NULL)
{
return false;
}
pRdValue = lpOutBuf[0];
return true;
}
public static bool ISA_Write(int hISA_DIO, int nSeg, uint nOffset, byte ucWrValue)
{
ISA_BUS_ACCESS isabus;
uint lpBytesReturned = 0;
isabus.dwCmd = 1;
isabus.dwSeg = (uint)nSeg;
isabus.dwOffset = nOffset;
isabus.dwValue = (uint)ucWrValue;
int size = Marshal.SizeOf(typeof(ISA_BUS_ACCESS));
byte[] lpIntBuf = new byte[size];
IntPtr buffer = Marshal.AllocHGlobal(size);
try
{
Marshal.StructureToPtr(isabus, buffer, false);
Marshal.Copy(buffer, lpIntBuf, 0, size);
}
finally
{
Marshal.FreeHGlobal(buffer);
}
if (!DeviceIoControl(hISA_DIO, // file handle to the driver
ISA_IOCTL_READ_WRITE, // I/O control code
lpIntBuf, // in buffer
(uint)size, // in buffer size
null, // out buffer
0, // out buffer size
ref lpBytesReturned, // pointer to number of bytes returned
0)) // ignored (=NULL)
{
return false;
}
return true;
}
static void Main(string[] args)
{
const int ISA_CS1 = 1;
int hISA;
hISA = OpenISA_DIO('ISA1:');
if( hISA == -1 )
{
Console.Write('Open ISA_DIO device fail!');
return;
}
bRet = ISA_Write(hISA, ISA_CS1, 0, b);
bRet = ISA_Read(hISA, ISA_CS1, 0, ref b);
CloseISA_DIO(hISA);
return;
}

3、傳遞結(jié)構(gòu)體的操作說明
該例程的ISA_Read，ISA_Write和函數(shù)中，DeviceIoControl的參數(shù)lpIntBuf需要傳遞一個結(jié)構(gòu)體指針，關(guān)于結(jié)構(gòu)體的操作需要按以下步驟。

所以首先需要定義一個和接口定義相同的結(jié)構(gòu)體，在C#中定義與C接口的結(jié)構(gòu)體需要使用StructLayout字段聲明結(jié)構(gòu)體的大小，和對齊規(guī)則。

在每個成員前面用FieldOffset字段設(shè)定該成員在結(jié)構(gòu)體中的偏移。

[StructLayout(LayoutKind.Explicit, Size = 16)]
public struct ISA_BUS_ACCESS
{
[FieldOffset(0)]public uint dwCmd; // = 0: Read, = 1: Write
[FieldOffset(4)]public uint dwSeg; // = 0: ISA_CS0, = 1: ISA_CS1
[FieldOffset(8)]public uint dwOffset;
[FieldOffset(12)]public uint dwValue; // only lower byte valid
}

然后設(shè)定結(jié)構(gòu)體各成員值，將結(jié)構(gòu)體拷貝到byte[]中，在C#中將結(jié)構(gòu)體拷貝到byte數(shù)組需要使用Marshal類。

首先計算結(jié)構(gòu)體大小
int size = Marshal.SizeOf(typeof(ISA_BUS_ACCESS));

創(chuàng)建一個byte[]
byte[] lpIntBuf = new byte[size];

用AllocHGlobal申請一塊非托管空間，并獲得該空間的指針
IntPtr buffer = Marshal.AllocHGlobal(size);

然后用StructureToPtr將結(jié)構(gòu)體拷貝到指針位置，再用Copy將指針位置數(shù)據(jù)拷貝到byte數(shù)組。因為之前申請了內(nèi)存空間，使用try-finally確報用FreeHGlobal釋放空間

try
{
Marshal.StructureToPtr(isabus, buffer, false);
Marshal.Copy(buffer, lpIntBuf, 0, size);
}
finally
{
Marshal.FreeHGlobal(buffer);
}

以上操作包括空間申請與釋放，效率并不高，為提高效率，應(yīng)當(dāng)將結(jié)構(gòu)體成員變量值直接賦值到byte數(shù)組相應(yīng)位置，如：
ISA_BUS_ACCESS isabus;
isabus.dwCmd = 1;

修改為
lpIntBuf[3] = 1;

注意整數(shù)的低位在高地址。

4、英創(chuàng)EM9170其他使用DeviceIoControl操作的設(shè)備dwIoControlCode值定義

//------------------------bsp_drivers----------------------------------
//winioctl
private const uint FILE_DEVICE_BUS_EXTENDER = 0x0000002a;
private const uint METHOD_BUFFERED = 0;
private const uint FILE_ANY_ACCESS = 0;
// GPIO IO Control Codes
private const uint GPIO_IOCTL_OUT_ENABLE = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | ( 3900<< 2) | (METHOD_BUFFERED);
private const uint GPIO_IOCTL_OUT_DISABLE = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3901 << 2) | (METHOD_BUFFERED);
private const uint GPIO_IOCTL_OUT_SET = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3902 << 2) | (METHOD_BUFFERED);
private const uint GPIO_IOCTL_OUT_CLEAR = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3903 << 2) | (METHOD_BUFFERED);
private const uint GPIO_IOCTL_PIN_STATE = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3904 << 2) | (METHOD_BUFFERED);
// ISA IO Control Codes
private const uint ISA_IOCTL_READ_WRITE = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3910 << 2) | (METHOD_BUFFERED);
private const uint ISA_IOCTL_BUS_RESET = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3911 << 2) | (METHOD_BUFFERED);
//private const uint ISA_IOCTL_REDA_CS1 = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3912 << 2) | (METHOD_BUFFERED);
//private const uint ISA_IOCTL_WRITE_CS1 = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3913 << 2) | (METHOD_BUFFERED);
// SPI IO Control Codes
private const uint CSPI_IOCTL_EXCHANGE = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3030 << 2) | (METHOD_BUFFERED);
// IRQ IO Control Codes
private const uint IOCTL_WAIT_FOR_IRQ = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3920 << 2) | (METHOD_BUFFERED);
private const uint IOCTL_SEND_EOI = (FILE_DEVICE_BUS_EXTENDER << 16) | (FILE_ANY_ACCESS << 14) | (3921 << 2) | (METHOD_BUFFERED);
//------------------------bsp_drivers_end------------------------------