Abstract:
A memory map evaluation tool is provided that organizes a program in a manner most compatible with use of a cache. The tool includes a method that involves executing a first version of the program according to a first memory map to generate a program counter trace, converting the program counter trace into a specific format and then translating the program counter trace into physical addresses using a memory map to be evaluated, different from the first memory map. Those physical addresses are then used to evaluate the number of likely cache misses using a model of a direct-mapped cache for the memory map under evaluation.
Abstract:
A bridge circuit includes two FIFO circuits each having an associated FIFO control circuit. In each FIFO control circuit, a write pointer register and a read pointer register for controlling the storage location for writing to and reading from the FIFO circuit are each controlled by control logic. The control logic is responsive to comparators which receive and compare the write pointer value and the retimed read pointer value to control the write pointer register, and receive and compare the read pointer value and the retimed write pointer value to control the read pointer register. The retiming circuits are configurable in response to a mode signal to provide different degrees of retiming. The maximum number of storage locations that can be full at any one time is a fixed limit.
Abstract:
A controller for controlling direct memory access. Such a controller is particularly applicable when applied to a transport interface in the receiver of a digital set-top-box for television systems. A storage means stores the base and top addresses of a circular buffer in a memory to which received data is to be forwarded and stored, and a write pointer for such buffer is also stored in the storage means. Addressing circuitry generates the address to which the receive data is to be written in dependence on the stored base and top addresses and the write pointer. Output circuitry writes the data into the circular buffer at the location identified by the generated address.
Abstract:
A method and system for validating speculative load operations. The system identifies speculative load operations that might be executed in a code sequence and after translating the virtual address of the speculative load to a physical address, a speculative load control unit is used to define a plurality of memory regions and has means for checking whether the physical addresses lie within at least one of said defined memory regions. In this way, the control unit allows the mapping of large physical page size to RAM devices and the extra address space is filtered off by the control unit so that speculative loads are not carried out in unknown regions.
Abstract:
Solid state image sensors, and methods of operation thereof, includes an array of photosensitive pixels arranged in rows and columns and in which pixel data signals are read out from the pixels via column circuits, which introduces column fixed pattern noise to the signals. The signals are selectively inverted at the inputs to the column circuits and the inversion is reversed following output from the column circuits. Each column circuit may include an analog-to-digital converter and a digital inverter for inverting digital output therefrom. The selective inversion may be applied to alternate rows or groups of rows of the pixel data, and may be applied differently to different frames of the pixel data. These techniques result in column fixed pattern noise being modulated in a manner which makes the noise less apparent to the eye, and which facilitates subsequent cancellation of the noise.
Abstract:
A semiconductor integrated circuit for processing a plurality of received broadcast signals, such as GPS signals, is operable in two modes: acquisition and tracking. In an acquisition mode, a memory arrangement comprising two circulating shift registers circulates samples of a received signal for correlation with a locally generated version of a GPS code. In a tracking mode, the sampled signal is provided direct to the correlators. The same correlators are thereby used to increase acquisition speed.
Abstract:
There is disclosed a circuit and method for demultiplexing in a receiver a digital data stream including at least two types of data, so as to retain only those parts of the digital data stream required by the receiver. In one particular application, such a receiver is used in a television system having a digital set-top-box receiver. A first control circuit extracts a packet identifier from an input data packet in the digital data stream, and generates a signal in dependence on whether the input data packet is of the first or second type. Sets of information associated with the first types of data packets and required by the receiver are stored in a memory under the control of a second control circuit. A third control circuit, responsive to receipt of the first type of input data packet, determines whether at least part of the input data packet matches the stored sets of information, and sets a match signal responsive thereto.
Abstract:
A semiconductor integrated circuit, including a test scan arrangement has a plurality of scan chains arranged in pairs. These scan chains have input terminals for receiving test patterns, and outputs provided to compression logic such as a distributed XOR tree multiple input shift register to provide an output which is a compressed signal derived from the output test patterns. In an alternative configuration, the first scan chain of each pair is connected to the second scan chain of each pair, and the input terminal of the second scan chain becomes the output terminal. Thereby creating a longer scan chain of the first and second scan chains together with one input terminal and one output terminal. The two loads allow for efficient scanning in the first mode, or debugging to determine the position of a fault in the second mode.
Abstract:
A clock source selector for selecting either a first clock signal A or a second clock signal B in accordance with a switch request signal includes three retiming circuits each consisting of two clocked flip-flops. The switch request signal is first retimed relative to clock A to give a signal P, is then retimed relative to clock B to give a signal Q, and finally is retimed relative to clock A to give a signal R. Selector circuitry operates such that when signal Q is asserted, the second clock signal B is output, when neither signal P nor signal R, as combined by a NOR gate, are asserted, the first clock signal A is output, and at other times a zero level is output. The clock source selector can be used in an integrated circuit to form a glitch-free multiplexer.
Abstract:
A digital phase comparator circuit that determines and adjusts the relative phase of two digital clock signals derived from the same digital clock. The circuit having two inputs, one connected to receive each of the clock signals to be compared and including a latch circuit to receive one clock signal at the clock input, and the other clock signal at a data input. The latch circuit is arranged so that the output is equal to the signal at the data input when measured at the clock edge. The output is therefore a logic null1null when the second clock leads the first clock, and a logic null0null when the second clock lags the first clock.