In contrast to the generic base system, the data level libraries and services provided by VISTA (the PAI is the most important part for technology CAD) are all specific. The PAI is distinctly layered which provides a spectrum of interfaces for applications with different levels of abstraction and functionality.
From a strictly application-oriented (that is simulator-oriented) point of view, the low-level and low-functionality interfaces may seem redundant and will hardly be used. For all purposes which do not depend on the semantics of the data represented, these low-level, generic syntax-oriented interfaces have proven very valuable.
VORONOI operates entirely on PIF data. It reads an input PBF, produces an output PBF and determines the action to take from the contents of the input PBF. The data level integration is accomplished by re-using high-level application interfaces provided by VISTA. These are the g2s (for 2-dimensional Geometry Support), the gas (for Geometry-Attribute-Support), and the grs (for GRid Support) libraries (see also Figure 8.2).
The amount of source code
required for the integration is 24 kB. Compared to
the 280kB of application source code, this is less than 10%.
It should be noted that the PIF input and output capabilities of
VORONOI are more complex than those of classical simulation tools.
An arbitrary number of grids and attributes and a (single) geometry
are read and written!
VISTA provides several common numerics utilities, which are often used in simulation. VORONOI benefits from a linear solver library which is used to solve the linear system which arises from the discretization of the Laplace and biharmonic equations (Section 6.6).