Abstract: A parser and checksum circuit includes a 256-bit data bus, IPV4, IPV6, TCP, and UDP state signal buses, a checksum summer and compare circuit, four 64-bit parsing circuits, a V6 extension processor, and a parse state context circuit. Each of the 64-bit parsing circuits includes two 32-bit parsing circuits. The data bus receives a data signal that is part of a packet. IPV4, IPV6, TCP, and UDP state signals are each configurable into 1-hot states where at most 1-bit is digital logic high. Each of the 1-hot states corresponds to a segment of a packet header of one of the IPV4, IPV6, TCP, and UDP protocols. Each 32-bit parsing circuit receives a 1-bit shifted version of the state signals received by the adjacent 32-bit parsing circuit and receives a portion of the data signal. State signals and the data signal portion are received in parallel during a single clock cycle.

Abstract: Incoming frame data is stored in a plurality of dual linked lists of buffers in a pipelined memory. The dual linked lists of buffers are maintained by a link manager. The link manager maintains, for each dual linked list of buffers, a first head pointer, a second head pointer, a first tail pointer, a second tail pointer, a head pointer active bit, and a tail pointer active bit. The first head and tail pointers are used to maintain the first linked list of the dual linked list. The second head and tail pointers are used to maintain the second linked list of the dual linked list. Due to the pipelined nature of the memory, the dual linked list system can be popped to supply dequeued values at a sustained rate of more than one value per the read access latency time of the pipelined memory.

Abstract: A Network Flow Processor (NFP) integrated circuit receives, via each of a plurality of physical MAC ports, PCP (Priority Code Point) flows. The NFP also maintains, for each of a plurality of virtual channels, a linked list of buffers. There is one port enqueue engine for each physical MAC port. For each PCP flow received via the physical MAC port associated with a port enqueue engine, the engine causes frame data of the flow to be loaded into one particular linked list of buffers. Each engine has a lookup table circuit that is configurable so that the relative priorities of the PCP flows are reordered as the PCP flows are assigned to virtual channels. A PCP flow with a higher PCP value can be assigned to a lower priority virtual channel, whereas a PCP flow with a lower PCP value can be assigned to a higher priority virtual channel.

Abstract: A Network Flow Processor (NFP) integrated circuit receives, via each of a first plurality of physical MAC ports, one or more PCP (Priority Code Point) flows. The NFP also maintains, for each of a second plurality of virtual channels, a linked list of buffers. There is one port enqueue engine for each physical MAC port. For each PCP flow received via the physical MAC port associated with a port enqueue engine, the port enqueue engine causes frame data of the flow to be loaded into one particular linked list of buffers. Each port enqueue engine has a lookup table circuit that is configurable to cause multiple PCP flows to be merged so that the frame data for the multiple flows is all assigned to the same one virtual channel. Due to the PCP flow merging, the second number can be smaller than the first number multiplied by eight.

Abstract: An overflow threshold value is stored for each of a plurality of virtual channels. A link manager maintains, for each virtual channel, a buffer count. If the buffer count for a virtual channel is detected to exceed the overflow threshold value for a virtual channel whose originating PCP flows were merged, then a PFC (Priority Flow Control) pause frame is generated where multiple ones of the priority class enable bits are set to indicate that multiple PCP flows should be paused. For the particular virtual channel that is overloaded, an Inverse PCP Remap LUT (IPRLUT) circuit performs inverse PCP mapping, including merging and/or reordering mapping, and outputs an indication of each of those PCP flows that is associated with the overloaded virtual channel. Associated physical MAC port circuitry uses this information to generate the PFC pause frame so that the appropriate multiple enable bits are set in the pause frame.

Abstract: An overflow threshold value is stored for each of a plurality of virtual channels. A link manager maintains, for each virtual channel, a buffer count. If the buffer count for a virtual channel is detected to exceed the overflow threshold value for a virtual channel whose originating PCP flows were merged, then a PFC (Priority Flow Control) pause frame is generated where multiple ones of the priority class enable bits are set to indicate that multiple PCP flows should be paused. For the particular virtual channel that is overloaded, an Inverse PCP Remap LUT (IPRLUT) circuit performs inverse PCP mapping, including merging and/or reordering mapping, and outputs an indication of each of those PCP flows that is associated with the overloaded virtual channel. Associated physical MAC port circuitry uses this information to generate the PFC pause frame so that the appropriate multiple enable bits are set in the pause frame.

Abstract: Incoming frame data is stored in a plurality of dual linked lists of buffers in a pipelined memory. The dual linked lists of buffers are maintained by a link manager. The link manager maintains, for each dual linked list of buffers, a first head pointer, a second head pointer, a first tail pointer, a second tail pointer, a head pointer active bit, and a tail pointer active bit. The first head and tail pointers are used to maintain the first linked list of the dual linked list. The second head and tail pointers are used to maintain the second linked list of the dual linked list. Due to the pipelined nature of the memory, the dual linked list system can be popped to supply dequeued values at a sustained rate of more than one value per the read access latency time of the pipelined memory.

Abstract: A Network Flow Processor (NFP) integrated circuit receives, via each of a plurality of physical MAC ports, PCP (Priority Code Point) flows. The NFP also maintains, for each of a plurality of virtual channels, a linked list of buffers. There is one port enqueue engine for each physical MAC port. For each PCP flow received via the physical MAC port associated with a port enqueue engine, the engine causes frame data of the flow to be loaded into one particular linked list of buffers. Each engine has a lookup table circuit that is configurable so that the relative priorities of the PCP flows are reordered as the PCP flows are assigned to virtual channels. A PCP flow with a higher PCP value can be assigned to a lower priority virtual channel, whereas a PCP flow with a lower PCP value can be assigned to a higher priority virtual channel.

Abstract: A Network Flow Processor (NFP) integrated circuit receives, via each of a first plurality of physical MAC ports, one or more PCP (Priority Code Point) flows. The NFP also maintains, for each of a second plurality of virtual channels, a linked list of buffers. There is one port enqueue engine for each physical MAC port. For each PCP flow received via the physical MAC port associated with a port enqueue engine, the port enqueue engine causes frame data of the flow to be loaded into one particular linked list of buffers. Each port enqueue engine has a lookup table circuit that is configurable to cause multiple PCP flows to be merged so that the frame data for the multiple flows is all assigned to the same one virtual channel. Due to the PCP flow merging, the second number can be smaller than the first number multiplied by eight.

Abstract: An integrated circuit receives a DDR (Double Data Rate) data signal and an associated DDR clock signal, and communicates those signals from integrated circuit input terminals a substantial distance across the integrated circuit to a subcircuit that then receives and uses the DDR data. Within the integrated circuit, a DDR retiming circuit receives the DDR data signal and the associated DDR clock signal from the terminals. The DDR retiming circuit splits the DDR data signal into two components, and then transmits those two components over the substantial distance toward the subcircuit. The subcircuit then recombines the two components back into a single DDR data signal and supplies the DDR data signal and the DDR clock signal to the subcircuit. The DDR data signal and the DDR clock signal are supplied to the subcircuit in such a way that setup and hold time requirements of the subcircuit are met.

Abstract: A clock signal generation arrangement for generating clocking signals for use in a fault-tolerant computer system generates a timing signal in response to a common clock signal. The clock signal generation arrangement comprises a system clock signal generator and a clock signal recovery circuit interconnected by a plurality of clock signal transfer lines. The system clock signal generator generates, in response to a common clock signal, a plurality of system clock signals preferably of uniform frequency and phase for transmission over a like plurality of clock signal transfer lines. The clock signal recovery circuit receives the system clock signals from the clock signal transfer lines and generates a unitary timing signal. The clock signal recovery circuit includes a voting circuit, a latch circuit and a latch control circuit. The voting circuit generates a voted clock signal having signal transitions that are generally aligned with transitions of a majority of the system clock signals.

Abstract: An I/O controller for transferring data between a host processor and one or more I/O units. The controller interleaves processor command transfers (PIO) in the midst of direct memory access (DMA) transfers without repeated data moves. DMA transfers are suspended temporarily during the priority PIO transfer. An interrupt Scanner, for scanning the various I/O units, is also prioritized with respect to DMA and PIO transfers.

Abstract: A programmable, multi-level interrupt priority encoder which fields interrupts from connected devices, e.g., DMA engine, scanner, and timer, and signals an interrupt value, or priority level, associated with that device. These levels, which may range from zero to seven or more, depending upon the system with which it is applied, are used by the CPU to determine which of the plural interrupting devices to service. Using the encoder of the invention, multiple devices can be set at the same priority level.

Abstract: A fault-tolerant digital data processing system comprises a first input-output controller which communicates with at least one peripheral device over a peripheral device bus having first and second input/output buses, each carrying data, address, control, and timing signals from the input/output controller to the peripheral device. A device interface is coupled to the first and second input/output buses and to an associated peripheral device for transferring information between the buses and the associated peripheral device. In normal operation, the device interface applies duplicate information signals synchronously and simultaneously to the input/output buses for transfer to the input/output controller. The device interface also receives, in the absence of fault, duplicative information signal synchronously and simultaneously from the first and second input/output buses.

Abstract: A fault-tolerant digital data processing system comprises at least a first input/output controller communicating with at least one peripheral device over a peripheral device bus. The peripheral bus includes first and second input/output buses, each having means for carrying data, address, control, and timing signals. The input/output controller includes an element for applying duplicate information signals synchronously and simultaneously to the first and second input/output buses for transfer to the peripheral device. The input/output controller further includes a bus interface element for receiving, in the absence of fault, duplicative information signals synchronously and simultaneously from the first and second input/output buses.

Abstract: A fault-tolerant digital data processor includes a peripheral device controller for communicating with one or more peripheral devices over a peripheral device bus having first and second input/output buses, each carrying data, address, control, and timing information. Each peripheral device includes a device interface for transferring information signals between the associated peripheral device and the peripheral bus. The peripheral device controller includes a strobe element connected with the first and second input/output buses for transmitting thereon duplicative, synchronous and simultaneous strobe signals. These strobe signals define successive timing intervals for information transfers along the peripheral bus. Information transfers are normally effected by the transmission of duplicate information signals synchronously and simultaneously on the first and second input/output buses.

Abstract: A fault-tolerant digital data processing system comprises at least a first peripheral controller communicating with at least one peripheral device over a peripheral device bus having first and second input/output buses, each carrying data, address, control, and timing signals. The first peripheral controller includes a first device interface element for applying duplicate information signals synchronously and simultaneously to the first and second input/output buses for transfer to the peripheral device. The first device interface element also receives, in the absence of fault, duplicative information signals synchronously and simultaneously from the first and second input/output buses. A second peripheral controller is coupled to the peripheral device bus for receiving the first and second input signals identically with the first peripheral controller.

Abstract: A fault-tolerant digital data processing system comprises at least a first input/output controller communicating with at least one peripheral device over a peripheral device bus. The peripheral bus includes first and second input/output buses, each having means for carrying data, address, control, and timing signals. The input/output controller includes an element for applying duplicate information signals synchronously and simultaneously to the first and second input/output buses for transfer to the peripheral device. The input/output controller further includes a bus interface element for receiving, in the absence of fault, duplicative information signals synchronously and simultaneously from the first and second input/output buses.