Abstract: A laser driver for high speed interconnections may convert a digital signal to a current train of a bias mode to represent logical zero and of a modulation mode to represent logical one. An optical signal thus produced may include an optical offset. An optical receiver may include a photo-detector to receive the optical signal and generate a current signal, which includes a corresponding current offset. A first amplifier stage converts the current signal to a voltage signal and a second amplifier stage generates a digital output from the voltage signal. One or more low-pass filters may be used to filter the digital output and generate a filtered offset signal for a differential amplifier to generate an offset cancellation signal. The offset cancellation signal may be provided to offset cancellation circuitry to remove the current offset from the current signal generated by the photo-detector.

Abstract: A method for an extended precision integer divide algorithm includes separating an L-bit integer dividend into two equal width integer format portions, a first portion including lower M bits of the integer dividend and a second portion including upper M bits of the integer dividend, where M is equal to ½ L. An N-bit wide integer divisor is converted from an integer format into a floating point format divisor. The first integer portion is converted into a floating point format and divided by the floating point format divisor to obtain a first floating point quotient, which is converted into a first integer format quotient. The second integer portion is converted into a floating point format and divided by the floating point format divisor to obtain a second floating point quotient which is also converted to a second integer format quotient. Then first and second integer format quotients are summed together to generate a third integer format quotient.

Abstract: A method and apparatus is disclosed that computes multiple absolute differences from packed data and sums each one of the multiple absolute differences together to produce a result. According to one embodiment, a processor includes a decode unit to decode a packed sum of absolute differences (PSAD) instruction having an opcode format to identify a set of packed data operands. The decode unit initiates a sequence of operations on the set of packed data operands in response to decoding the PSAD instruction. An execution unit performs a first operation of the sequence of operations initiated by the decode logic, and a bus provides the execution unit with the set of packed data operands as identified in accordance with the opcode format.

Abstract: One embodiment of a laser driver for high speed interconnections includes a buffered level shifter to shift the input voltage level to an appropriate level. In some embodiments the buffered level shifter may be tuned to provide a desired level shift with impedance matched to the driving load. Another embodiment converts a digital signal to a current train of a bias mode to represent logical zero and of a modulation mode to represent logical one, wherein one or both of the bias mode and modulation mode may be adjusted, for example by a programmable control circuit or by an adaptive control circuit. Some embodiments also provide circuitry for reducing overshoot of the output signal.

Abstract: A method and apparatus for performing a shift operation on packed data elements having multiple values. One embodiment includes accessing the shift control signal of a first format from a memory. The shift control signal identifyies a first packed shift operation and whether the shift positions are byte positions or bit positions, and causes a processor to execute a set of control signals of a second format, thereby accessing the packed data, shifting the packed data by the number of shift positions according to the first packed shift operation, generating a first replacement data for one of the number of positions, and producing a shifted first packed data comprising the first replacement data.

Abstract: In a multiprocessor, access to shared resources is provided by a semaphore control mechanism, herein disclosed. The semaphore control mechanism provides for a high degree of programmable firmware reuse requiring relatively few modifications from a uniprocessor. The semaphore control mechanism receives one or more semaphore modification requests from one or more requesting devices, identifies an ownership state of a semaphore corresponding to the one or more semaphore modification requests, arbitrates to identify modification request from a particular requesting device to succeed if the identified ownership state corresponds to the particular requesting device or if the identified ownership state corresponds to no ownership.

Abstract: A method and apparatus for providing, in a processor, a shift operation on a packed data element having multiple values. One embodiment of a central processing unit (CPU) includes instruction fetch logic to fetch a single-instruction-multiple-data (SIMD) shift instruction. A register stores a multiple data elements to be operated upon by the SIMD shift instruction. A barrel shifter concurrently shifts the data elements in a bit-wise manner by a variable number of bit positions in response to the SIMD shift instruction.

Abstract: A method and apparatus for providing, in a processor, a shift operation on a packed data element having multiple values. The apparatus having multiple muxes, each of the multiple muxes having a first input, a second input, a select input and an output. Each of the multiple bits that represent a shifted packed intermediate result on a first bus is coupled to the corresponding first input. Each of the multiple bits representing a replacement bit for one of the multiple values is coupled to a corresponding second input. Each of the multiple bits driven by a correction circuit is coupled to a corresponding select input. Each output corresponds to a bit of a shifted packed result.

Abstract: A method and apparatus for including in a processor instructions for performing multiply-add operations on packed byte data. In one embodiment, a processor is coupled to a memory. The memory has stored therein a first packed byte data and a second packed byte data. The processor performs operations on data elements in said first packed byte data and said second packed byte data to generate a third packed data in response to receiving an instruction. A plurality of the data elements in this third packed data storing the result of performing multiply-add operations on data elements in the first and second packed byte data.

Abstract: Nonlinear filtering and deblocking applications utilizing SIMD (single instruction multiple data) sign and absolute value operations are disclosed. The method of one embodiment includes receiving first data for a first block and second data for a second block. The first data and said second data include a plurality of rows and columns of pixel data. A block boundary between the first block and the second block is characterized. A correction factor for a deblocking algorithm is calculated with a first instruction for a sign operation that multiplies and with a second instruction for an absolute value operation. Data for pixels located along said block boundary between the first and second black are corrected.

Abstract: A method and apparatus is disclosed that uses an arithmetic circuit for adding numbers represented in a redundant form to also subtract numbers received in redundant form, including numbers received from a bypass circuit. A non-propagative comparator circuit is then used to compare a given value with a result from the arithmetic circuit to determine if the result is equal to the given value. All of the operations described above can be accomplished without propagating carry signals throughout the circuitry. The method includes generating a complemented redundant form of at least one number supplied to the arithmetic circuit in redundant form. It also includes providing adjustment input to the arithmetic circuit to augment a result produced through the arithmetic circuit. This adjustment causes the arithmetic circuit to generate a valid outcome in redundant form as a result of a subtraction operation if the arithmetic operation is subtraction.

Abstract: A method and apparatus for including in a processor instructions for performing horizontal intra-add operations on packed data. One embodiment of the processor is coupled to a memory. The memory has stored therein at least a first packed data. The processor performs operations on data elements in the first packed data to generate a plurality of data elements in a second packed data in response to receiving an instruction. At least two of the plurality of data elements in the second packed data store the results of an intra-add operation, at least one of these results coming from the operation on data elements of the first packed data. One embodiment of a software method utilizes horizontal intra-add instructions for performing butterfly computations as may be employed, for example, in Walsh-Hadamard transforms or in Fast-Fourier Transforms.

Abstract: In a multiprocessor, access to shared resources is provided by a semaphore control mechanism, herein disclosed. The semaphore control mechanism provides for a high degree of programmable firmware reuse requiring relatively few modifications from a uniprocessor. A machine check abort (MCA) handling mechanism is disclosed, which works with the semaphore control mechanism in the multiprocessor to provide improved system availability and reliability. The MCA handling mechanism provides for synchronization of multiple processors and shared resources and for timely execution resumption within the processors that remain on-line.

Abstract: A method and apparatus are described for converting a number from a floating point format to an integer format or from an integer format to a floating point format responsive to a control signal of a control signal format. Numbers are stored in the floating point format in a register of a first set of architectural registers in a packed format. One or more numbers in the floating point format are converted to the integer format and placed in a register of a second set of architectural registers in a packed format. Conversion from integer format to floating point format is performed in a similar manner. A floating point arithmetic apparatus is described that provides for converting a plurality of numbers between integer formats and a floating point formats, further providing for conversion operations that require a greater data path width than floating-point arithmetic operations.