Direct memory access (dma) transfer buffer processor

Abstract

A DMA (Direct Memory Access) Exchange Block (DXB) processor may include a receive processor for writing data from a local memory to a host memory over a bus, e.g., a Peripheral Component Interconnect Extended (PCI/X) bus, and a transmit processor for writing data retrieved from the host memory over the bus to the local memory. Each processor may include a high priority queue and a normal priority queue. A controlling program generates DXBs, each of which include a tag assigned by the controlling program and memory descriptors corresponding to a direct memory access operation. The memory descriptor may include a host memory descriptor (address/length) and one or more local memory descriptors. The controlling program writes a DXB to one of the queues in a cache line spill operation. The transfer processor may include two channel registers, enabling the processor to perform two PCI/X data transfers simultaneously.