Abstractions in Asim

This page discusses details of the Asim system and the abstraction and modeling mechanisms presented here.

Note that Asim is not a publicly available tool and so it is difficult to determine exactly what the tool provides and does not.

Flexible Model Of Concurrency

To the best of our knowledge, Asim has two methods to allow components to communicate. If communication occurs such that the receiver can see the data in the same cycle as the sender, then communication occurs via function calls, like in sequential simulators.

Optimizable/Analyzable Model of Concurrency

There is insufficient information to determine what can and cannot be analyzed or optimized in the model of concurrency.

When communication occurs across cycles, Asim has a very structured and strictly enforced communication system to ensure that the data is only read when it is available. This is because one of Asim's design goals was to forbid approximations in signal arrival that caused errors in performance evaluation.

The difficulty with this dual method of composition is that component granularity is controlled by the timing of the components external communication. This is undesirable since it makes it difficult for the component to be used across designs with different timing even though the internal functionality is the same. Detailed discussion of these issues can be found here

Data Abstraction

Since Asim is based on C++ it provides the same data abstractions as the base language. It isn't clear if any additional data abstractions are provided.

Component Polymorphism

Polymorphism can be achieved through templates. However, it isn't clear if this feature of C++ can be used to allow for polymorphic data type for communication. Even if it is possible, the process of using templates for communication forces users to explicitly specify the type used in many objects where the type can be unambiguously inferred with no deleterious effects. This is especially true with long chains of components.

The cumbersome nature of template based polymorphism is less of an issue in Asim however. The most cumbersome use of templates occurs when there are a large collection of simple components interacting to implement a larger component. However, Asim's Model of Computation (MoC) makes this difficult and thus polymorphism itself becomes less important since the resultant benefits are not realized.