Abstract: A computer system having a hierarchical bus structure that allows decoupling of a local bus from a global bus thereof. Decoupling of the local bus is achieved through use of an asynchronous system bus adapter which includes a local bus adapter for handling transactions, initiated by a system device coupled to the global bus, that require access to a local device coupled to the local bus and a global bus adapter for handling transactions, initiated by a local device coupled to the local bus, that require access to a system device coupled to the system bus. The local bus adapter is further configured to issue signals which prevent the global bus adapter from handling transactions initiated by local devices coupled to the local bus while transactions initiated by system devices coupled to the global bus are on-going.

Abstract: A system for receiving transaction requests from a plurality of data access devices, coupling them to a shared memory having an input queue and identifying each completed transaction with the requesting device. The system includes a controller for receiving the requests and selectively coupling them to a shared memory input queue. A first-in-first-out identification memory stores a requesting device identifier which the controller uses to route transaction completion control signals and data back to the device which requested the transaction.

Abstract: A bridge for connecting a DSP to an ASIC on-chip bus as a master on the bus. The bridge includes a DSP instruction unit master interface and a DSP data unit master interface to convert DSP instruction unit and data unit external signals into bus protocol signals. An arbiter is provided to receive the signals from the two DSP interfaces and selectively pass the signals to a generic bus master which couples the signals to the on-chip bus. A synchronization unit is provided to insure alignment of positive clock transitions between the different clock frequencies of the ASIC and the DSP and to buffer signals as needed. The generic bus master couples signals from the arbiter and the synchronization unit to the ASIC bus in full compliance with the bus protocol.

Abstract: A high-speed barrel shifter (20) includes a shifter array (25) having a matrix of transistors (40) located at intersections of rows and columns of the matrix (40). The rows and columns alternately function as source and destination terminals. A fill portion (48) fills either a predetermined value or a data-dependent value such as a sign bit into vacated bit positions along rows in a bottom left portion (42). Thus the barrel shifter (20) can perform a data-dependent fill instruction within the shifter array (25) and avoids extra clock cycles associated with post-array processing. In one embodiment, an isolation portion (44, 45) separates a top right portion (41) of the matrix (40) from the bottom left portion (42) along a diagonal (43). The isolation portion (44, 45) isolates transistors in the bottom left portion (42), which are associated with rotates and fills, from transistors in the top right portion (41), which are associated with shifts, according to the direction of the shift.

Abstract: A priority encoder (12) has a most significant bit circuitry (18), a first less significant bit circuitry (20) and a second less significant bit circuitry (22). The priority encoder detects a leading one within a plurality of data bits. Each data bit is associated with a different one of a plurality of input signals. The most significant bit circuitry is coupled to a first one of the input signals and generates a first output signal and a parallel blocking signal. Both of the first output signal and the parallel blocking signal are representative in a first logic state of a leading one associated with the first signal. The first less significant bit cell is coupled to a second one of the input signals and to the parallel blocking signal. The first less significant bit cell generates a second output signal and a less significant carry signal. Both the second output signal and the less significant carry signal are representative in a first logic state of a leading one associated with the second input signal.