Applications and games that depend on DirectX use the DirectXSetup function to install their system components into an existing Windows installation. It optionally updates the display and audio drivers to support DirectX during the DirectX installation process. This process is designed to happen smoothly, without adversely affecting the user's system. Older drivers are upgraded whenever possible to prevent reduced performance or stability of all DirectX applications on a computer.
DirectXSetup is provided to each application from Dsetup.dll, Dsetup16.dll, and Dsetup32.dll. Therefore all three of these files are included with your product's setup program. You can find the declarations for DirectSetup in Dsetup.h.
Note The DirectXSetup function overwrites system components from previous versions of DirectX. For example, if you install DirectX 5 on a system that already has DirectX 3 components, all DirectX 3 components will be overwritten. Because all DirectX components comply with Component Object Model (COM) backward compatibility rules, software written for DirectX 3 will continue to function properly.
DirectX 5 requires the installation of all components. Previous versions of DirectX allowed the installation of individual DirectX components. However, the amount of disk space saved was minimal. Current DirectX components are tightly integrated together for maximum performance. Hence, all components need to be installed for any one of them to work.
The DirectX Programmer's Reference of the Platform SDK contains the \Redist directory. Setup programs that use the DirectXSetup function must distribute the appropriate files from this directory as specified in the End User License Agreement (EULA).