Stream device drivers are accessed by applications using the file system API. This really limits the interface capabilities of device drivers. All that the file system interface allows the developer to perform are read, write, or seek operations. This is fine for real file I/O, but stream device drivers, though regarded as files are completely different. To allow the device driver to communicate custom operations it can perform on the peripheral device it controls, a special mode of operation was created. This method is not unique to Windows Embedded Compact 7 or Windows CE, it is part of the Win32 API and it has been part of UNIX and UNIX like systems since 1979, and allows stream device drivers to communicate custom operations to an application by calling the DeviceIoControl function. This function is implemented by Device Manager and exposed by it so it can be called from within user mode applications.
KeywordsCritical Section Kernel Mode Device Type Device Driver Peripheral Device
Unable to display preview. Download preview PDF.