Development of the NoGAP CL Hardware Description Language and its Compiler

Abstract: The need for a more general hardware description language aimed specifically at processors, and vague notions and visions of how that language would be realized, lead to this thesis. The aim was to use the visions and initial ideas to evolve and formalize a language and begin implementing the tools to use it. The language, called NoGAP Common Language, is designed to give the programmer freedom to implement almost any processor design without being encumbered by many of the tedious tasks normally present in the creation process. While evolving the language it was chosen to borrow syntaxes from C++ and verilog to make the code and concepts easy to understand. The main advantages of NoGAP Common Language compared to RTL languages are; -the ability to define the data paths of instructions separate from each other and have them merged automatically along with assigned timings to form the pipeline. -having control paths automatically routed by activating named clauses of code coupled to control signals. -being able to specify a decoder, where the instructions and control structures are defined, that control signals are routed to. The implemented compiler was created with C++, Bison, and Flex and utilizes an AST structure, a symbol table, and a connection graph. The AST is traversed by several functions to generate the connection graph where the instructions of the processor can be merged into a pipeline. The compiler is in the early stages of development and much is left to do and solve. It has become clear though that the concepts of NoGAP Common Language can be implemented and are not just visions.