Processor Description Languages

5.1 Language-based ASIP Modeling 99

instruction word sizes. This set of coding roots R

c

contains coding roots that are

mutually exclusive to each other. For RISC architectures with a fixed instruction

word, size R

c

contains only a single element. For VLIW architectures, each coding

root r ∈ R

c

decodes one from a set of parallel instructions.

Instruction syntax description

The syntax section of LISA operation is used to descr ibe the instructions’ assembly

syntax. It is described as a sequence of several syntax elements. A syntax element

is either a terminal character sequence with “ADD,”“SUB,” or a nonterminal. The

nonterminal syntax element can point