Map Between Console Functions and Driver Functions (Compact 7)
3/12/2014
Because calls that are made from the console application are routed through Device Manager, it is important to understand how application calls and driver functions correspond to one another.
The following table shows the driver functions that are invoked by Device Manager when core function calls are made from the console application.
| Core function | Driver function |
|---|---|
ActivateDeviceEx (or ActivateDevice) |
DLLMain xxx_Init |
CreateFile |
xxx_Open |
WriteFile |
xxx_Write |
ReadFile |
xxx_Read |
SetFilePointer |
xxx_Seek |
DeviceIoControl |
xxx_IOControl |
NA |
xxx_Cancel |
CloseHandle |
xxx_PreClose xxx_Close |
DeactivateDevice |
xxx_PreDeinit xxx_Deinit |
NA |
xxx_PowerDown |
NA |
xxx_PowerUp |
Notice that calling ActivateDeviceEx, CloseHandle, or DeactivateDevice from the console application causes Device Manager to make more than one call to the driver. When debugging for the first time, you might set breakpoints on each of these driver functions in order to trace the code.
In the preceding table, the driver functions are listed in the order that they are called. For example, when you call ActivateDeviceEx, DLLMain is called followed by xxx_Init.
When ActivateDeviceEx is called, Device Manager also calls xxx_Open, xxx_IOControl, xxx_PreClose, and xxx_Close. This function sequence gives Device Manager an early opportunity to query the device driver for power capabilities. If the device is turned off prior to other calls being made to the driver, Device Manager can make appropriate power management calls to the driver.
Note
Microsoft recommends that you use the xxx_IOControl function instead of xxx_PowerUp and xxx_PowerDown to implement power management functionality, including suspend and resume functionality.
For more information about the relationship between driver functions and Device Manager, see Plan Your Device Driver.