Abstract: A bifurcated selector for transmitting transactions from a plurality of transaction queues out a port of a switch. A transaction scheduler selects transactions of the queues for transmission to a device coupled to the port. A policy manager enforces a scheduling policy of the queues. An interface couples the policy manager to the transaction scheduler. The interface includes first signals for the transaction scheduler to receive from the policy manager a priority for each queue. The transaction scheduler selects the transactions for transmission to the device based on the priorities. The interface also includes second signals for the policy manager to receive from the transaction scheduler transaction transmission information for each queue. The policy manager updates the priorities based on the transaction transmission information. The transaction transmission information comprises an indication of which of the queues a transaction was selected from for transmission.

Abstract: The present invention provides an automated digital circuit design tool that reduces or eliminates adverse timing constraints due to an inherent clock signal skew, and applications thereof In an embodiment, an automated design tool according to the invention generates a clocking system that includes a clock signal generator, control logic, enable logic, and at least one clock gater. The clock signal generator generates a clock signal that is distributed to various logic blocks of the digital circuit using a buffered clock tree. The enable logic receives input values from the control logic and provides a control signal to the clock gater. When enabled, the clock gater allows a clock signal to pass through to multiple registers. An early clock signal is provided to register(s) in the control logic, which allows for an increased clock frequency while still meeting timing constraints.

Abstract: Systems and methods that allow for extracting a field from data stored in a pair of registers using two instructions. A first instruction extracts any part of the field from a first register designated as a first source register, and executes a second instruction extracting any part of the field from a second general register designated as a second source register. The second instruction inserts any extracted field parts in a result register.

Abstract: A multi-streaming processor has a plurality of streams for streaming one or more instruction threads, a set of functional resources for processing instructions from streams, and interrupt handler logic. The logic detects and maps interrupts and exceptions to one or more specific streams. In some embodiments, one interrupt or exception may be mapped to two or more streams, and in others two or more interrupts or exceptions may be mapped to one stream. Mapping may be static and determined at processor design, programmable, with data stored and amendable, or conditional and dynamic, the interrupt logic executing an algorithm sensitive to variables to determine the mapping. Interrupts may be external interrupts generated by devices external to the processor software (internal) interrupts generated by active streams, or conditional, based on variables. After interrupts are acknowledged, streams to which interrupts or exceptions are mapped are vectored to appropriate service routines.

Abstract: A method and apparatus within a processing system is provided for associating shadow register sets with interrupt routines. The invention includes a vector generator that receives interrupts, and generates exception vectors to call interrupt routines that correspond to the interrupts. The exception vector considers the type of interrupt and the priority level of the interrupt when selecting the exception vector. Shadow set mapping logic is coupled to the vector generator. The mapping logic contains a number of fields that correspond to the different exception vectors that may be generated. The fields are programmable by kernel mode instructions, and contain data mapping each field to one of a number of shadow register sets. When an interrupt occurs, the vector generator generates a corresponding exception vector. In addition, the shadow set mapping logic looks at the field corresponding to the exception vector, and retrieves the data stored therein.

Abstract: A three-tiered TLB architecture in a multithreading processor that concurrently executes multiple instruction threads is provided. A macro-TLB caches address translation information for memory pages for all the threads. A micro-TLB caches the translation information for a subset of the memory pages cached in the macro-TLB. A respective nano-TLB for each of the threads caches translation information only for the respective thread. The nano-TLBs also include replacement information to indicate which entries in the nano-TLB/micro-TLB hold recently used translation information for the respective thread. Based on the replacement information, recently used information is copied to the nano-TLB if evicted from the micro-TLB.

Abstract: The present invention provides an automated digital circuit design tool that reduces or eliminates adverse timing constraints due to an inherent clock signal skew, and applications thereof. In an embodiment, an automated design tool according to the invention generates a clocking system that includes a clock signal generator, control logic, enable logic, and at least one clock gater. The clock signal generator generates a clock signal that is distributed to various logic blocks of the digital circuit using a buffered clock tree. The enable logic receives input values from the control logic and provides a control signal to the clock gater. When enabled, the clock gater allows a clock signal to pass through to multiple registers. An early clock signal is provided to register(s) in the control logic, which allows for an increased clock frequency while still meeting timing constraints.

Abstract: A method of controlling the exclusivity mode of a level-two cache includes generating level-two cache exclusivity control information at a processor in response to an exclusivity mode indicator, and utilizing the level-two cache exclusivity control information to configure the exclusivity mode of the level-two cache.

Abstract: An interface between electronic devices uses a credit-based flow protocol with sustained bus signals. An initiating device waits for credit to issue a command to a target device. When credit is available, the initiating device issues the command to the target device such that the command is accessible by the target device until a new command is issued. The command may include a read or write request to the target device.

Abstract: The present invention provides alignment and ordering of vector elements for SIMD processing. In the alignment of vector elements for SIMD processing, one vector is loaded from a memory unit into a first register and another vector is loaded from the memory unit into a second register. The first vector contains a first byte of an aligned vector to be generated. Then, a starting byte specifying the first byte of an aligned vector is determined. Next, a vector is extracted from the first register and the second register beginning from the first bit in the first byte of the first register continuing through the bits in the second register. Finally, the extracted vector is replicated into a third register such that the third register contains a plurality of elements aligned for SIMD processing. In the ordering of vector elements for SIMD processing, a first vector is loaded from a memory unit into a first register and a second vector is loaded from the memory unit into a second register.

Abstract: A processor includes multiple processor core units, each including a processor core and a cache memory. Victim lines evicted from a first processor core unit's cache may be stored in another processor core unit's cache, rather than written back to system memory. If the victim line is later requested by the first processor core unit, the victim line is retrieved from the other processor core unit's cache. The processor has low latency data transfers between processor core units. The processor transfers victim lines directly between processor core units' caches or utilizes a victim cache to temporarily store victim lines while searching for their destinations. The processor evaluates cache priority rules to determine whether victim lines are discarded, written back to system memory, or stored in other processor core units' caches. Cache priority rules can be based on cache coherency data, load balancing schemes, and architectural characteristics of the processor.

Abstract: Microprocessor having a power-saving instruction cache way predictor and instruction replacement scheme. In one embodiment, the processor includes a multi-way set associative cache, a way predictor, a policy counter, and a cache refill circuit. The policy counter provides a signal to the way predictor that determines whether the way predictor operates in a first mode or a second mode. Following a cache miss, the cache refill circuit selects a way of the cache and compares a layer number associated with a dataram field of the way to a way set layer number. The cache refill circuit writes a block of data to the field if the layer number is not equal to the way set layer number. If the layer number is equal to the way set layer number, the cache refill circuit repeats the above steps for additional ways until the block of memory is written to the cache.

Abstract: A multi-streaming processor has a plurality of streams for streaming one or more instruction threads, a set of functional resources for processing instructions from streams, and interrupt handler logic. The logic detects and maps interrupts and exceptions to one or more specific streams. In some embodiments, one interrupt or exception may be mapped to two or more streams, and in others two or more interrupts or exceptions may be mapped to one stream. Mapping may be static and determined at processor design, programmable, with data stored and amendable, or conditional and dynamic, the interrupt logic executing an algorithm sensitive to variables to determine the mapping. Interrupts may be external interrupts generated by devices external to the processor software (internal) interrupts generated by active streams, or conditional, based on variables. After interrupts are acknowledged, streams to which interrupts or exceptions are mapped are vectored to appropriate service routines.

Abstract: Systems and methods that allow for extracting a field from data stored in a pair of registers using two instructions. A first instruction extracts any part of the field from a first register designated as a first source register, and executes a second instruction extracting any part of the field from a second general register designated as a second source register. The second instruction inserts any extracted field parts in a result register.

Abstract: A multiprocessing system is disclosed. The system includes a multithreading microprocessor, including a plurality of thread contexts (TCs), each comprising a first control indicator for controlling whether the TC is exempt from servicing interrupt requests to an exception domain for the plurality of TCs, and a virtual processing element (VPE), comprising the exception domain, configured to receive the interrupt requests, wherein the interrupt requests are non-specific to the plurality of TCs, wherein the VPE is configured to select a non-exempt one of the plurality of TCs to service each of the interrupt requests, the VPE further comprising a second control indicator for controlling whether the VPE is enabled to select one of the plurality of TCs to service the interrupt requests.

Abstract: A configurable coprocessor interface between a central processing unit (CPU) and a coprocessor is provided. The coprocessor interface has an instruction transfer signal group for transferring different instruction types from the CPU to the coprocessor, sequentially or in parallel, a busy signal group, for allowing the coprocessor to signal the CPU that it cannot receive a transfer of one or more of the different instruction types, and an instruction order signal group for indicating to the coprocessor a relative execution order for multiple instructions that are transferred in parallel. In addition, the coprocessor interface includes separate data transfer signal groups for data being transferred from the CPU to the coprocessor, and for data being transferred from the coprocessor to the CPU, along with a data order signal group for indicating a relative order of data (if transferred out-of-order).

Abstract: An embedded system or system on chip (SoC) includes a secure JTAG system and method to provide secure on-chip control, capture, and export of on chip information in an embedded environment to a probe. In one embodiment, the system comprises encryption logic associated with a JTAG subsystem and decryption logic in the probe for encrypted JTAG read traffic. Inverted encryption/decryption logic provides bi-directional encryption and decryption of JTAG traffic. Encrypted information includes both authentication of valid probe/target interface and encryption of debug data.

Abstract: A system for managing packets incoming to a data router has a local packet memory (LPM) mapped into pre-configured memory units, to store packets for processing, an external packet memory (EPM), a first storage system to store packets in the LPM, and a second storage system to store packets in the EPM. The system is characterized in that the first storage system attempts to store all incoming packets in the LPM, and for those packets that are not compatible with the LPM, relinquishes control to the second system, which stores the LPM-incompatible packets in the EPM.

Abstract: A modular subtraction instruction for execution on a microprocessor having at least one register. The instruction includes opcode bits for designating the instruction and operand bits for designating at least one register storing an offset index, a decrement value, and an address index. When the modular subtraction instruction is executed on the microprocessor, the address index is modified by the decrement value if the address index is not zero and is modified by the offset index if the address index is zero. For example, the address index is repeatedly decremented using the decrement value until it reaches zero, and then the address index is reset back to the offset index. The operand bits may include multiple fields identifying multiple registers selected from the general purpose registers of the microprocessor. The modular subtraction instruction enables access to a buffer in memory in circular fashion by virtue of its operation.

Abstract: The present invention provides processing systems, apparatuses, and methods that reduce power consumption with the use of a loop buffer. In an embodiment, an instruction fetch unit of a processor initially provides instructions from an instruction cache to an execution unit of the processor. While instructions are provided from the instruction cache to the execution unit, instructions forming a loop are stored in a loop buffer. When a loop stored in the loop buffer is being iterated, the instruction cache is disabled to reduce power consumption and instructions are provided to the execution unit from the loop buffer. When the loop is exited, the instruction cache is re-enabled and instructions are provided to the execution unit from the instruction cache.