Processor Description Languages

194 CHAPTER 8 TIE

in the next example. Finally, the export keyword specifies that the value of this

state is to be made visible outside the processor as a new top-level interface.This is

described in detail in Section 8.7.1.

Consider a modified version of the

dotprod instruction of Section 8.3.1,in which

a 40-bit accumulator is used. The accumulator can no longer be stored in the AR

register file, which is only 32-bits wide. The following example illustrates the use

of TIE state to create such an instruction. It also uses the built-in module TIEmac,

described in Section 8.3.4, to perform the multiply and accumulate operation.

state ACC 40 add_read_write ...