Processor Description Languages

228 CHAPTER 9 MADL—An ADL Based on a Formal

ISAs, especially orthogonal ISAs such as RISC. For the toy instruction set shown

in Fig. 9.5, since the operands and the opcodes are orthogonal, they can be sep-

arated into dif ferent nodes. The common nodes among different instructions are

then merged to form the AND-OR graph.

9.3.2 The Core Layer

The core layer uses the dynamic OSM model as its semantic model,and theAND-OR

graph as its syntax model. Thus, the task of designing the layer is to combine these

two to create a description language that is expressive and efficient for describ-

ing architectural details. These include the encoding, assembly syntax, ...