Agere Systems Guardian Corp.

Agere Systems Inc.

Stefan Thurnhofer

John Susantha Fernando

This invention concerns a novel traceback memory management method and apparatus in which a memory stores Viterbi trellis state records and shifts the records in a manner so that the memory mirrors the relevant portion of the trellis accessed during the traceback for error correction and decoding. Several pointers are used so that a random access memory (RAM) can store and access the Viterbi trellis state records with only a minimum amount of hardware required to implement the memory accesses. In certain instances, where memory length is a power of 2, entire elements needed in the address generation steps are eliminated by the invention, thereby saving valuable chip area and clock cycles.

Traceback buffer management for VLSI Viterbi decoders

A programmable multi-mode accelerator is disclosed for use with a programmable processor or microprocessor. The programmable multi-mode accelerator allows a programmable processor to execute specific algorithms, such as certain types of finite impulse response (FIR), correlation and Viterbi computations, that require low-precision operations at an extremely high rate. The accelerator extends the digital signal processor's performance into the required range for low-precision computations. The accelerator can be coupled with the main data path of a programmable processor or microprocessor and can directly read and write to the main register files of the programmable processor. In an illustrative implementation, the accelerator data path accesses its input values (source operands) directly from a main register file of the programmable processor and writes results back into a second main register file. The accelerator allows a plurality of low-precision algorithms requiring primarily addition or multiply-add computations, such as finite impulse response, correlation and Viterbi computations, to utilize the same adder cells. The accelerator includes a multi-mode adder that can be programmatically reconfigured to perform various addition computations. In a first mode, referred to as the &ldquo;single-add mode,&rdquo; the adder operates as a 17-input 16-bit adder. The single-add mode can be utilized to perform finite impulse response and correlation computations. The second mode, referred to as the &ldquo;ACS mode,&rdquo; can be utilized to perform Viterbi computations. The accelerator has a small instruction set and instruction memory and, once started by the main data path, the accelerator executes its own instruction stream. In addition, the accelerator includes a delay line having delays of z or z .

Programmable accelerator for a programmable processor system

A parallel processing architecture for a digital processor capable of alternately operating in a single threaded mode, a SIMD (single instruction, multiple data) mode and a MIMD (multiple instructions, multiple data) mode. The instruction set for the processor includes instructions for switching between modes and exchanging data between the parallel processing paths. The hardware in any instruction path or portion of an instruction path which is not being used is deactivated to save power.

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Newport Beach, CA, United States of America

Stefan Thurnhofer