SuperH (SH) 64-Bit RISC Series SH-5 System Architecture, Volume ...

PRELIMINARY DATASuperHyway architecture 17A particular module may be able to handle requests for multiple destination fields.Multiple different destination field values may map to the same p-port. It is commonfor memory modules to handle requests for a contiguous range of destination fieldvalues. This allows a memory module to provide a physical address space, largerthan that possible with a single destination field value, which is viewed ascontiguous physical memory when addressed by the p-protocol.Packet classificationA packet has a class and a type.A packet’s class is either a request packet or a response packet. The response packetclass is subdivided into two different kinds of response packet: ordinary responsepackets and error response packets. The term ‘response packet’ refers to either anordinary response packet or an error response packet, unless the surroundingcontext makes it clear that a particular kind of response packet is intended.A packet’s type indicates the memory transaction associated with that packet. TheSH-5 implementation uses four basic kinds of memory operation: read, write,atomic read-modify-write and cache-coherency operations.These are shown in the table below:Transaction name Request parameters a ResponseparametersMemory read Load8 addr 8 , byte-mask word bLoad16 addr 16 2 wordsLoad32 addr 32 4 wordsMemory write Store8 addr 8 , byte-mask, word -Atomicread-modify-writeStore16Store32addr 16 , byte-mask,2wordsD R A FTaddr 32 , byte-mask,4wordsSwap8 addr 8 , byte-mask, word word--Table 2: SH-5 p-router transactions05-SA-10001 v1.0SuperH, Inc.SH-5 System Architecture, Volume 1: System