Abstract: A modular reusable bus architecture enhances testability of an integrated computer system in which multiple modules communicate over a system bus. Under the modular reusable bus architecture, the system bus can be configured to operate in different operation modes. In one embodiment, the bus architecture provides a test mode for testing an individual module within the integrated computer system, separate from the other modules. In another embodiment, the bus architecture configures the system bus to provide access to configuration registers and memory units disposed within each module, otherwise inaccessible in normal system operation. The modular reusable architecture can support any types and any number of modules, including modules incorporating analog and digital circuitry, and modules operating under different clock domains.

Abstract: A circuit having a single branch, which is controllable to implement either a left or right shift of bits of a data word. Preferably, the circuit is controllable to implement any selected one of the following operations: a left or right shift of bits of the word; and rotation (to the left or right) of bits of the word. In a preferred implementation, the circuit includes a set of multiplexer stages and circuitry for selectively inverting the order of the bits of the word input to, and the word output from, the set of multiplexer stages. Each of the multiplexer stages shifts the bits of the word it receives either by zero bits (in response to a first control signal), or by a positive number of bits (in response to a second control signal). By selectively controlling various subsets of the multiplexer stages, the bits of the input word can be shifted by any of a number of places (from zero to N, where N is some positive number).

Abstract: A circuit for performing either single precision or double precision arithmetic operations on data, a system including such a circuit, and a method implemented by the system. Preferably, the circuit is an arithmetic manipulation unit (AMU) which performs arithmetic operations on N-bit words in a single precision mode and on 2N-bit words in a double precision mode. The AMU concatenates two N-bit words in the double precision mode thus producing a 2N-bit operand, and performs a selected one of several arithmetic operations on the operand and a second 2N-bit operand. Preferably, the AMU performs a double precision operation in two cycles: a first cycle generating a first operand and loading the operand to an output register; and a second cycle in which a second operand is generated from a second pair of N-bit parts from the memory, the first operand is fed back from the output register, and an arithmetic operation is performed on the two operands.