Overview of Jazz

What is Jazz?

Jazz is a programming language designed to facilitate the implementation of large and complex digital synchronous circuits. Its main motivations is to improve code reusability in harware development through the use of high-level constructions such as objects. This goal is achieved through a state-of-the-art object system that allows flexible, modular, and generic circuit descriptions. However, this powerful language is easy to learn and to use: its syntax and basic object model are similar to Java.

In practice, the Jazz system is composed of a compiler and runtime environment that translate the high-level description of a device into a low-level structured set of boolean equations (net-list). The net-list generated from a single Jazz source code is used to simulate and debug the device (by software) and to automatically synthetize it on various types of programmable chips (FPGA). The net-list could also be used to verify logical properties of the device.

The Jazz language is fully portable and completely independent of the host platform. It allows separate compilation and precompiled libraries thanks to an intermediary compiled bytecode, pretty much the same way as in Java. The compiler and its associated tools for simulation and implementation are themselves entirely written in Java.

Main features of the language

Jazz is declarative: the programmer declares equations and needs not worry about the precise mechanism of evaluation. This is well adapted to the descriptions of circuits, which indeed are sets of boolean equations. For example, here is the definition of a function that creates three equations using two xor gates and one multiplexor:

// Full Adder: a+b+c = s+2r
fun FullAdd(a, b, c)  =  (s , r) {

  x = a ^ b;
  s = x ^ c;
  r = cond(x, c, a);
}

Jazz is object-oriented: it implements a sophisticated modular object system that allows parameterized types, polymorphic multi-methods and higher-order functions. Its basic use is similar to Java but the system is much more powerful. Yet, it remains simple because the programmer is not required to write unnecessary type information. For example, in the function FullAdd, the type of parameters and results is inferred by the system (type inference). To give the taste of the Jazz class system, here is a short example of a user class:

final class NetPair implements BooleanAlgebra {
  x1: Net;
  x2: Net;
}

Builtin.(^)(x@NetPair, y@NetPair) =
   new NetPair(x1 = x.x1^y.x1, x2 = x.x2^y.x2);

Builtin.cond(x@NetPair, y@NetPair, z@NetPair) = 
   new NetPair(x1 = cond(x.x1, y.x1, z.x1),
               x2 = cond(x.x2, y.x2, z.x2));

Net is the primitive type of circuit wires, so the class NetPair implements a pairs of wires. The definition of operators ^ and cond (which, when applied to nets, behaves as the mux operator) on NetPair allows FullAdd to now operate on this user-defined class.

Jazz is strongly typed: programs are statically checked for type errors. This eliminates many programming errors. In particular, it guarantees the integrity of the data manipulated at runtime. The language is inherently safe.

Jazz provides a rich set of primitive types including arbitrary precision integers and rationals, floating-point numbers and strings that can be used to control the circuit generation. The language is easily extended through native methods implemented in Java.

Jazz is portable: the source language, the intermediary bytecode, and the libraries are completely independent of the platform of execution. Jazz is available on 5 different architectures (Windows 9x/NT, Linux, Digital Unix, Sun Solaris, and HP-UX) and can also be used on any Java-conformant platform.

An overview of Jazz

What is Jazz?

Main features of the language