Register window

Register windows are a form of organization of process-oriented register. These allow you to quickly switch back and forth between different processes (also known as multithreading ) without the hassle of reloading the register contents, since the register can be switched to the active process required by the " window ".

Construction

The available registers are in three sections (windows ) divided: In, Out and Local. A Current Window Pointer ( CWP ) points to the currently active window. Now changes the process ( by starting a new or ending of an old process ), the CWP is incremented ( increased) or decremented ( decreased) to point to the next window. The register window used so far are the new process by renaming the registers still available, but under new names.

Benefits

With relatively few registers, many processes it makes it possible to operate in parallel, without consuming the contents of the registers A or outsource.

Disadvantages

In deeply nested procedure calls, the advantage of register windows can not be exploited because of a certain number of active processes, saturation occurs, depending on the number of register windows.

Implementation

The SUN UltraSPARC II used 32 64 -bit registers according to the above principle.

Swell

• Andrew S. Tanenbaum, James Goodman: Computer Architecture, 4th edition, 2001