Abstract: A microprocessor architecture having extendible logic. One or more customized applications are available to the instruction pipeline. The customizable applications may include software, extension logic instruction or register, dynamically configurable hardware logic, or combinations of these. In order to enable the operating system to interface with the customized extension applications, at least one software extension is provided to the operating system. When a specific extension is requested a software exception is generated by the OS. In response to the exception, the least one software extension is called to handle context switch and dynamic configuration of the extendible logic of the microprocessor.

Abstract: A microprocessor architecture having extendible logic. One or more customized applications are available to the instruction pipeline. The customizable applications may include software, extension logic instruction or register, dynamically configurable hardware logic, or combinations of these. In order to enable the operating system to interface with the customized extension applications, at least one software extension is provided to the operating system. When a specific extension is requested a software exception is generated by the OS. In response to the exception, the least one software extension is called to handle context switch and dynamic configuration of the extendible logic of the microprocessor.

Abstract: A method of performing branch prediction in a microprocessor using variable length instructions is provided. An instruction is fetched from memory based on a specified fetch address and a branch prediction is made based on the address. The prediction is selectively discarded if the look-up was based on a non-sequential fetch to an unaligned instruction address and a branch target alignment cache (BTAC) bit of the instruction is equal to zero. In order to remove the inherent latency of branch prediction, an instruction prior to a branch instruction may be fetched concurrently with a branch prediction unit look-up table entry containing prediction information for a next instruction word. Then, the branch instruction is fetched and a prediction is made on this branch instruction based on information fetched in the previous cycle. The predicted target instruction is fetched on the next clock cycle.

Abstract: A method of managing the configuration, design parameters, and functionality of an integrated circuit (IC) design using a hardware description language (HDL). Instructions can be added, subtracted, or generated by the designer interactively during the design process, and customized HDL descriptions of the IC design are generated through the use of scripts based on the user-edited instruction set and inputs. The customized HDL description can then be used as the basis for generating “makefiles” for purposes of simulation and/or logic level synthesis. The method further affords the ability to generate an HDL model of a complete device, such as a microprocessor or DSP. A computer program implementing the aforementioned method and a hardware system for running the computer program are also disclosed.