Domain-specific programming assistance in an embedded DSL for generating processor emulators

This paper presents a design approach for developing an embedded domain-specific language (DSL) with domain-specific programming assistance. To demonstrate the proposed approach, we describe the design of our processor description language called MELTRANS, which is an embedded DSL hosted by Java. MELTRANS is used to generate a fast processor emulator with dynamic binary translation. Although such embedded DSLs have provided only poor domain-specific assistance for programming, MELTRANS improves this poorness. Our idea is to let the integrated development environment (IDE) of the host language provide better programming assistance using domain-specific knowledge. To this end, we decompose a program in MELTRANS into several Java classes corresponding to a different concern and set a rule for the description order. The language runtime takes each class and generates not only the code for processor emulators but also superclasses for classes written later. The user writes each class describing a concern as the subclasses of a generated class. The generated classes enable the user to benefit from programming assistance by Java IDEs in a more domain-specific style. While MELTRANS is hosted in Java, the generated emulators are written in C++. To validate our design, we implement several emulators in MELTRANS and perform experiments with them. The results show that our domain-specific programming assistance can effectively reduce the amount of code that needs to be written by the user, and the generated emulators achieve over 1,000 MIPS.