We present a domain-specific-language (DSL) for writing instances of a class of filter programs. The values in the language are symbolic and independent of a concrete precision. Efficient code generation is required to fit the program onto a target device limited in both memory and processing power. We construct an interpreter for the DSL in a language specific to the device which contains the semantics of the target instruction set embedded within a declarative meta-language. The compiler is automatically generated from the interpreter through specialisation. This extension of the instruction set allows the construction of an interpreter for the DSL that is both simple and clear. In particular it allows us to declare static representations of the symbolic values, and have the specialisation of the code produce operate upon these values in the instruction set of the target device.