Abstract: An improved method of optimizing the instruction set of a digital processor using code compression. In one embodiment, the method comprises obtaining an assembly language program to be used for the optimization process; calculating the static frequency of each instruction type from the base instruction set; sorting the instruction types by frequency; determining the number and type of instructions necessary for correct program execution; creating a compressed instruction set encoding; re-evaluating the compressed instruction according to the foregoing steps; and generating an instruction set encoding for the compressed instruction set. Improved compressed instruction formats and register structures useful in a processor are also disclosed. A computer program and apparatus for synthesizing logic implementing the aforementioned data cache architecture and pipeline performance enhancements are further disclosed.

Abstract: An improved method and apparatus for performing operations (such as Viterbi decode) in digital processors using a reduced number of cycles. In one aspect, the invention comprises efficient methods for performing multiple “butterfly” add-compare-select (ACS) operations using an improved dual butterfly (DVBF) extension instruction added to the instruction set of a user-configured processor. The DVBF extension allows performance of two butterfly operations in a single cycle. In another aspect, an improved path metric addressing scheme is disclosed. An integrated circuit (IC) device incorporating the aforementioned features, and method of designing such IC, are also disclosed.

Abstract: Apparatus and methods for real-time control using a data processor. In one aspect, the invention comprises an improved processor having one or more extension instructions (and associated supporting pipeline hardware) which are specially adapted for use in a real-time control algorithm running on the processor. In one exemplary embodiment, the processor is a 32-bit pipelined RISC device having custom multiply (CMUL) and multiply-accumulate (CMAC) instructions added to the extension instruction set to optimize algorithm performance in real-time linear time-invariant (LTI) applications. Specialized extension hardware, and methods for generating a processor design adapted for real-time control applications are also disclosed.

Abstract: Apparatus and methods for integrated circuit (IC) design, including management of the configuration, design parameters, and functionality of a design in which custom instructions or other design elements may be controlled by the designer. In one exemplary embodiment, a computer program rendered in an object-oriented language implementing the aforementioned methods for designing user-customized digital processors is disclosed. Design iteration, component encapsulation, use of human-readable file formats, extensible dynamic GUIs and tool sets, and other features are employed to enhance the functionality and accessibility of the program. Components within the design environment comprise encapsulated objects which contain information relating to interfaces with other components in the design, hierarchy, and other facets of the design process.

Abstract: An improved method and apparatus for performing operations (such as Viterbi decode) in digital processors using a reduced number of cycles. In one aspect, the invention comprises efficient methods for performing multiple “butterfly” add-compare-select (ACS) operations using an improved dual butterfly (DVBF) extension instruction added to the instruction set of a user-configured processor. The DVBF extension allows performance of two butterfly operations in a single cycle. In another aspect, an improved path metric addressing scheme is disclosed. An integrated circuit (IC) device incorporating the aforementioned features, and method of designing such IC, are also disclosed.

Abstract: An improved method and apparatus for controlling and implementing instructions in a pipelined central processing unit (CPU) or user-customizable microprocessor. In a first aspect of the invention, an improved method of permitting programmer control of jump instruction interlocks is disclosed. In one embodiment, a minimum of one cycle is required between an instruction that sets flags and a branch taken as a result of those flags; an interlock is used to detect a branch preceded by an instruction setting the flags to ensure that the instruction immediately preceding the branch can not affect the branch outcome. In a second embodiment, a jump instruction following a flag setting instruction whose flags may affect the outcome of the jump is stalled until all flags are set. In a second aspect of the invention, a method of synthesizing a processor design incorporating the aforementioned interlocks is disclosed.