Section: New Results

N-Synchronous Languages

The n-synchronous model introduced a way to compose streams which have almost the same clock and can be synchronized through the use of a finite buffer.

We have designed the language Lucy-n to program in this model of computation [4] , [48] . This language is similar to the first order synchronous data-flow language Lustre in which a buffer operator is added. A dedicated type system allows to check that programs can be executed in bounded memory and to compute the buffers sizes needed. Technically it is done through the introduction of a subtyping constraint at each bufferization point.

To solve the subtyping constraints we have defined an algorithm that uses an improved version of the state-of-the-art abstraction. We have proved the correctness properties of this new abstraction in Coq.

We also worked on new typing algorithms that do not use clock abstraction and thus allows to model Latency Insensitive Design [5] in Lucy-n  [48] .

• A. Guatto, together with L. Mandel and M. Pouzet, worked on the code generation for Lucy-n. They investigated two approaches. The first one was to use the schedules and buffer sizes computed by the compiler to generate a classical Lustre program. The second approach was to define a dynamic scheduling protocol similar to the ones used in latency insensitive designs.

• L. Mandel, in collaboration with F. Plateau (Prove&Run), developed a new resolution constraint algorithm for the clocking of Lucy-n programs [4] . Even if the new algorithm is less efficient that the one using abstraction, it has the advantage to be more precise and thus to accept more programs.

• L. Mandel, F. Plateau and M. Pouzet have extended the Lucy-n language with a new operator to be able to model Latency Insensitive Designs. Thanks to the new resolution constraint algorithm, the Lucy-n compiler is able to compute static schedules for such designs [5] .