Lucent Technologies Inc.

Agere Systems Inc.

At+t Corp.

Agere Systems Guardian Corp.

At&t Ipm Corp.

Lucent Technology

Mark Ernest Thierbach

Larry R Tate

Mohammad Shafiul Mobin

David M Blaker

Gregory S Ellard

Marc Stephen Diamondstein

Homayoon Sam

Douglas J Rhodes

Sivanand Simanapalli

Lawrence Allen Rigge

Mazhar M Alidina

Alan Joel Greenberger

Andrew A Wang

Ravi Jammula

Carl R Holmqvist

An apparatus and method for timing calibration of write and read-back data exchanges between respective dies of an external memory/external device has a master arbiter or, alternatively, a test bus between a system bus master interface and an external memory controller for driving the external memory/external device, a calibration circuit under control of the master arbiter via a test bus master interface to provide stepped-through time delays for test data exchanges between the dies, and the calibration circuit obtains pass/fail data indicating pass or fail of the varied time delays for the test data exchanges. A processor system at the system bus master interface selects calibration values corresponding to pass data, and applies the calibration values to the respective dies for timing of write and read-back data exchanges between the dies.

Optimum timing of write and read clock paths

A method of assigning unique instruction codes to instructions in an instruction set is disclosed. Such an encoded instruction set is also disclosed. Instructions are grouped according to the particular resources used, where all of the instructions in a group have one or more resource types in common. The position of the highest order active bit in the code is used to identify which resource group a particular instruction belongs to. Instructions in a resource group reserve the same number of bits to identify the specific resources to be used, and no more bits are reserved than required. The remaining unassigned bits are used to encode particular command codes. When such an encoded command is decoded, the resource group is identified by determining the highest order active bit in the instruction. This information is used to determine which bits in the instruction are command bits and which are resource-identifying bits. The specific resource information is extracted and used to select the designated resources to be used in executing the command. This encoding scheme eliminates wasted bits in instructions and thereby increases the number of instructions which can be implemented.

Method for optimally encoding a set of instruction codes for a digital processor having a plurality of instruction selectable resource types and an associated optimized set of instruction codes

A near-orthogonal dual-MAC instruction set is provided which implements virtually the entire functionality of the orthogonal instruction set of 272 commands using only 65 commands. The reduced instruction set is achieved by eliminating instructions based on symmetry with respect to the result of the commands and by imposing simple restrictions related to items such as the order of data presentation by the programmer. Specific selections of commands are also determined by the double word aligned memory architecture which is associated with the dual-MAC architecture. The reduced instruction set architecture preserves the functionality and inherent parallelism of the command set and requires fewer command bits to implement than the full orthogonal set.

Near-orthogonal dual-MAC instruction set architecture with minimal encoding bits

A novel table look-up/indirect addressing system and method uses a dual fetch Harvard architecture to accomplish one full table look-up access per instruction cycle. The offset access fetch, the indirect data fetch and the table offset and base address addition are all performed during a single cycle. The system and method also accommodate data accesses using packed (half word) offsets.

System and method for performing table look-ups using a multiple data fetch architecture

An improved apparatus and method for providing addresses for accessing circular memory buffers is provided. An apparatus comprised of a first feedback circuit, a second feedback circuit, a beginning address register, an ending address register, and a comparator circuit. A control circuit is also provided. The beginning and ending address registers preferably include the beginning and ending addresses respectively of a circular memory buffer. The first feedback circuit is comprised of a first register, a first phase delay register, a first adder, a first displacement register, and a first multiplexer. The second feedback circuit is preferably comprised of a second register, a second phase delay register, a second adder, and a second displacement register. Preferably the control circuit based at least partially on contents of the first register, beginning address register, and ending address register, and upon a comparison by the comparison circuit between the contents of the second register and the ending address register causes either the first register or the second register contents to be supplied to an address bus.

Address generator circuity for a circular buffer

A non-aligned double word fetch buffer is integrated into a digital signal processor to handle non-aligned double word (32 bit) fetches. When a misaligned double word fetch is detected, the buffer causes a two cycle non-interruptable instruction to be initiated. The first cycle is a 16-bit misaligned data fetch. The address pointer is incremented by 2 and stored in a temporary pointer register. The second cycle is a 32-bit double word fetch based on the temporary pointer with its least significant bit set to 0 (an aligned fetch). The low word from this fetch is used to satisfy the current misaligned double word fetch and the high word is stored in a temporary buffer register in case it proves useful in subsequent misaligned double fetch instructions. Finally, the temporary address pointer is incremented by 2 for possible use in subsequent misaligned fetches. If a subsequent misaligned fetch using the same address pointer is detected, a one-cycle misaligned double word fetch may be simulated by using the buffered memory fetch data combined with another aligned double word fetch and an appropriate pointer update. A double word per cycle data rate may thereby be maintained during an entire sequence of misaligned data fetches, except when processing the first state of the loop, during which time the buffer is set up.

Non-aligned double word fetch buffer

An application-specific single chip digital processor having flexible design expansion capability with minimal impact on the performance of a processor core. The processor core has an ALU and a register file (accumulators). The output of the ALU is connected to a multiplexer whose output is connected to the input of the register file. The output of the register file connects to one input of the ALU. A function unit, separate from the core, has an input connected to the output of the register file and an output connected to another input to the multiplexer. The core operates with a predefined instruction set. The function unit, which may be redesigned depending on the application, operates with a reserved (uncommitted) instruction set under control of the core.

Core processor with customizable function unit

A modulo address generation circuit for generating multiple-word memory accesses for use in a computer system. The circuit includes an address pointer latch for retaining a current address pointer, an adder for receiving the current address pointer as a first input and a displacement as a second input. The adder for adding the inputs to provide an output. A comparator compares the current address pointer to an ending address of a circular buffer ignoring least significant bits thereof when the displacement is greater than one. The comparator provides an output that is a first state when the inputs are the same and an output that is a second state when the outputs are different. A control circuit is adapted to receive an indicator of the beginning address of the circular buffer, an indicator of the current address pointer, and an indicator of the ending address of the circular buffer. The control circuit provides the output of the adder to the address pointer latch as an updated address pointer when the indicators take on predetermined values and the comparator output is in the second state. The control circuit provides the beginning address to the address pointer latch as an updated address pointer when the indicators take on predetermined values and the comparator output is in the first state. An advanced address pointer may be used to enhance performance in misaligned memory accesses.

Modulo address generator for generating an updated address

Flexible single chip digital processor architecture

In accordance with the present invention, a technique for efficiently utilizing memory in determining which next state accumulated cost to retain, such as in a communication system or a Viterbi decoder. The system includes a memory having a portion of registers allocated to a first array and a portion of registers allocated to a second array. The technique includes retrieving a present state accumulated cost from a storage register of the first array and calculating a next state accumulated cost based on the present state accumulated cost. The next state accumulated cost is stored in a storage register of the second array. The second array is designated as containing present state accumulated costs. A present state accumulated cost is retrieved from a storage register of the second array and used in calculating a subsequent next state accumulated cost. The subsequent next state accumulated cost is stored in a storage register of the first array.

Efficient utilization of present state/next state registers

A signal processor with an embedded Viterbi co-processor is disclosed. The Viterbi branch metric unit contains embedded metric units which calculate either Euclidean or Manhattan metrics for MLSE or deconvolution operations.

Digital signal processor

An integrated circuit includes a digital signal processor (DSP) and an error correction co-processor (ECCP) that implements a Viterbi decoding function. The DSP and ECCP share a block of multi-port memory, typically by bus multiplexing a dual-port RAM. When the ECCP possesses the RAM, it inhibits the DSP from accessing that block of the RAM by asserting an EBUSY flag. This technique conserves and optimizes the RAM usage, allowing the DSP and ECCP to advantageously be formed on the same integrated circuit chip.

Growing community of inventors

South Whitehall, PA, United States of America

Mark Ernest Thierbach