A structured macro assembler for the Event Handler

A description is given of a portable macro cross-assembler that has been developed for the Event Handler using UNIX compiler construction tools. The assembler is implemented as separate code generation and preprocessor programs. Besides the basic Event Handler instructions, the code generator supports structured conditionals, structured loops, and high-level-language-like constant calculations. The preprocessor allows for symbolic text constants, symbolic numeric constants with computed values, messages, include files, macros, and conditional assembly. These features can either enhance the direct programming of the Event Handler or define minilanguages that hide programming details from the user. The assembler is not dependent on a particular data acquisition system and thus may be of interest to other Event Handler users