Creating an application-specific processor is an effective and popular way to solve many problems in embedded hardware design using FPGAs, ASICs, or custom silicon. Programming these processors is complicated by the lack of toolchain support for creating the necessary binary code as part of hardware design, implementation, and evaluation. Hardware developers who cannot create their own ad-hoc assembler are left to hand-assemble their code into binary instructions which is both painful and error prone.

We present a tool that supports the rapid creation of assemblers for application-specific processors. A single language is used to specify both instruction formats as collections of bit fields and the instantiation of those formats into sequences of binary instructions as a single, homogeneous activity that is designed to be as familiar and accessible to hardware designers as possible. The output from the tool can be used directly by hardware synthesis tools to initialise the program memory of an application-specific processor.