TABLE OF CONTENTS xpipes is a SystemC library of parameterizable, synthesizable NoC components (NI switch and link modules), optimized for low-latency and high-frequency operation [44]. Communication is packet switched, with source routing (based on street-sign encoding) and wormhole switching.
The xpipes NI is designed as a bridge between an OCP interface and the NoC-switching fabric. Its purposes are the synchronization between OCP and xpipes timings, the packeting of OCP transactions into xpipes flits and vice versa, the computation of routing information, and the buffering of flits to improve performance. The xpipes NI is designed to comply with version 2.0 of the OCP specifications. In addition to the core OCP signals, support includes for example the ability to perform both non-posted or posted writes (i.e., writes with or without response) and various types of burst transactions, including reads with single request and multiple responses.
To provide complete deployment flexibility, the NI is parameterizable in both the width of OCP fields and of xpipes flits. Depending on the ratio between these parameters, a variable amount of flits is needed to encode an OCP transaction. For any given transaction, some fields (such as the OCP MAddr wires, specific control signals, routing information) can be transmitted just once; in contrast, other fields (such as the OCP MData or SData wires) need to be transmitted repeatedly, for example during a burst transaction. Thus, the NI is built around two registers: one holds the transaction header, while the second one holds the...
