#include <windows.h>
#include <stdio.h>

#define DEVICE_NAME	"test.dat"
#define BUFFER_SIZE	512
//假設該文件大于或等于BUFFER_SIZE

VOID CALLBACK MyFileIOCompletionRoutine(
  DWORD dwErrorCode,                // 對于此次操作返回的狀態
  DWORD dwNumberOfBytesTransfered,  // 告訴已經操作了多少字節,也就是在IRP里的Infomation
  LPOVERLAPPED lpOverlapped         // 這個數據結構
)
{
	printf("IO operation end!\n");
}

int main()
{
	HANDLE hDevice = 
		CreateFile("test.dat",
					GENERIC_READ | GENERIC_WRITE,
					0,
					NULL,
					OPEN_EXISTING,
					FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED,//此處設置FILE_FLAG_OVERLAPPED
					NULL );

	if (hDevice == INVALID_HANDLE_VALUE) 
	{
		printf("Read Error\n");
		return 1;
	}

	UCHAR buffer[BUFFER_SIZE];

	//初始化overlap使其內部全部為零
	//不用初始化事件!!
	OVERLAPPED overlap={0};

	//這里沒有設置OVERLAP參數，因此是異步操作
	ReadFileEx(hDevice, buffer, BUFFER_SIZE,&overlap,MyFileIOCompletionRoutine);

	//做一些其他操作，這些操作會與讀設備并行執行

	//進入alterable
	SleepEx(0,TRUE);

	CloseHandle(hDevice);

	return 0;
}