Credit flow control scheme in a router with flexible link widths utilizing minimal storage

An apparatus, comprising:

• one or more routers in a fabric of a Network on a Chip (NoC) which encompasses systems including an integrated circuit, wherein the one or more routers are configured to propagate flits from source locations to destination locations along inter-router physical links of the fabric of the NoC, the flits including incoming flits and outgoing flits, each of the routers having one or more input ports and one or more output ports, wherein each of the routers is configured to
• (a) use one or more input virtual channels (VCs) with each input port, wherein each of the input VCs is associated with a first VC storage reserved only for the incoming flits associated with that input VC and a second VC storage shared among the incoming flits of all of the input VCs associated with the input port,
• (b) use one or more output VCs with each output port, wherein each of the output VCs is used to forward the outgoing flits to a downstream router, wherein each of the output VCs is associated with a credit count,
• (c) perform a link width conversion when a width of the one or more output VCs is different than a width of the one or more input VCs, comprising a narrow-to-wide conversion where the incoming flits are accumulated to form a wider outgoing flit, a wide-to-narrow conversion where the incoming flits are broken up into narrower outgoing flits, or no width conversion where the outgoing flits have a same width as the incoming flits, and
• (d) perform flit flow control using credit generation and credit tracking.