Processor Description Languages

5.2 Automatic Software Toolsuite Generation 109

a constraint can also be imposed by the designer on the maximum silicon area

of a CI.

■ Architectural constraints: Assuming the CI is synthesized on a dedicated Cus-

tom Functional Unit (CFU), communication frequently takes place via the

core’s General Purpose Register (GPR) file. Due to the limited instruction

word length, generally, only a few GPRs are available for this purpose (e.g.,

2 input GPRs and 1 output GPR per CI). Furthermore, a CI may or may not

access the data memory, and other constraints may hold for immediate con-

stants, etc. Although these constraints impose tight limitations, the CFU ...