Machine Descriptions to Build Tools for Embedded Systems Machine Descriptions for Machine-level Tools

Because of poor tools, developing embedded systems can be unnecessarily hard. Machine descriptions based on register-transfer lists (RTLs) have proven useful in building retargetable compilers, but not in building other retargetable tools. Simulators, assemblers, linkers, debug-gers, and proolers are built by hand if at all|previous machine descriptions have lacked the detail and precision needed to generate them. This paper presents detailed and precise machine-description techniques that are based on a new formalization of RTLs. Unlike previous notations, these RTLs have a detailed, unambiguous, and machine-independent semantics , which makes them ideal for supporting automatic generation of retargetable tools. The paper also gives examples of-RTL, a notation that makes it possible for human beings to read and write RTLs without becoming overwhelmed by machine-dependent detail. Developers for embedded systems often work without the beneet of the best software tools. Embedded systems can have unusual architectural features, and new processors can be introduced rapidly. Development is typically done on stock processors, and cross-development can make it hard to get basic compilers , assemblers, linkers, and debuggers, let alone proolers, tracers, test-coverage analyzers, or general code-modiication tools. One reason such tools are seldom available is that machine-dependent detail makes it hard to build them. This paper describes work in progress on Computer Systems Description Languages (CSDL). CSDL descriptions are intended not only to provide precise, formal notations for describing machine-dependent detail, but also to support automatic generation of useful tools. Moreover, CSDL descriptions are intended to be reusable, so we can build up a body of descriptions, e.g., of popular embedded processors, that will be useful for building future as well as current tools. The design goals for CSDL are { CSDL should support a variety of machine-level tools while remaining independent of any one in particular.