Hardware Specification with C $\varvec{\lambda }$ aSH

Abstract

C$\lambda$aSH is a recently developed system to specify and synthesize hardware architectures, strongly based on the functional programming language Haskell. Different from other existing approaches to describe hardware in a functional style, C$\lambda$aSH is not defined as an embedded language inside Haskell, but instead, C$\lambda$aSH uses Haskell itself to specify hardware architectures. In fact, every C$\lambda$aSH specification is an executable Haskell program. Hence, the simulation of a hardware architecture is immediate, and all abstraction mechanisms that are available in Haskell are maintained in C$\lambda$aSH, insofar they are directly applicable to the specification of hardware.

This paper describes several examples of specifications of hardware architectures in C$\lambda$aSH to illustrate the various abstraction mechanisms that C$\lambda$aSH offers. The emphasis is more on the C$\lambda$aSH-style of specification, than on the concrete technical details of C$\lambda$aSH. Often, the specifications are given in plain Haskell, to avoid some of the specific C$\lambda$aSH details that will be indicated in a separate section.

The given examples include regular architectures such as a ripple carry adder, a multiplier, vector and matrix multiplications, finite impulse response filters, and also irregular architectures such as a simple Von Neumann style processor and a reduction circuit. Finally, some specific technicalities of C$\lambda$aSH will be discussed, among others the processing pipeline of C$\lambda$aSH and the hardware oriented type constructions of C$\lambda$aSH.

Jan Kuper—This work is partly supported by EU project POLCA, FP7-ICT-2013-10, grant agreement no. 610686.