MADL-An ADL Based on a Formal and Flexible Concurrency Model¹

This chapter presents the operation state machine (OSM) model, which provides a high- level and flexible abstraction mechanism to model the data and control semantics of a microprocessor. Based on this model, a two-layer Mescal architecture description language (MADL) is designed to support accurate modeling of a broad range of architectures. The two layers are the core layer and the annotation layer, and this two-layered structure separates essential architecture properties from volatile implementation-dependent information, thus lengthening the lifetime of MADL. This technique enables users to factor descriptions to significantly reduce their length. With proper annotation schemes, MADL descriptions can be used to assist the generation of efficient cycle accurate simulators, instruction set simulators, disassemblers, register allocators, and instruction schedulers. The MADL framework is capable of generating two types of cycle accurate simulators, one based on the dynamic-operation state machine (OSM) model in MADL, and the other an optimized one based on the translated static-OSM model. The use of MADL improves the productivity of simulator development as MADL descriptions are very compact and the synthesized simulators mostly have better simulation performance than hand-coded OSM simulators.