Patent application number | Description | Published |
20080263336 | Processor Having Efficient Function Estimate Instructions - High-precision floating-point function estimates are split in two instructions each: a low precision table lookup instruction and a linear interpolation instruction. Estimates of different functions can be implemented using this scheme: A separate table-lookup instruction is provided for each different function, while only a single interpolation instruction is needed, since the single interpolation instruction can perform the interpolation step for any of the functions to be estimated. Thus, significantly less overhead is incurred than would be incurred with specialized hardware, while still maintaining a uniform FPU latency, which allows for much simpler control logic. | 10-23-2008 |
20090024684 | Method for Controlling Rounding Modes in Single Instruction Multiple Data (SIMD) Floating-Point Units - A method for controlling rounding modes in a single instruction multiple data (SIMD) floating-point unit is disclosed. The SIMD floating-point unit includes a floating-point status-and-control register (FPSCR) having a first rounding mode bit field and a second rounding mode bit field. The SIMD floating-point unit also includes means for generating a first slice and a second slice. During a floating-point operation, the SIMD floating-point unit concurrently performs a first rounding operation on the first slice and a second rounding operation on the second slice according to a bit in the first rounding mode bit field and a bit in the second rounding mode bit field within the FPSCR, respectively. | 01-22-2009 |
20100100578 | DISTRIBUTED RESIDUE-CHECKING OF A FLOATING POINT UNIT - A distributed residue checking apparatus for a floating point unit having a plurality of functional elements performing floating-point operations on a plurality of operands. The distributed residue checking apparatus includes a plurality of residue generators which generate residue values for the operands and the functional elements, and a plurality of residue checking units distributed throughout the floating point unit. Each residue checking unit receives a first residue value and a second residue value from respective residue generators and compares the first residue value to the second residue value to determine whether an error has occurred in a floating-point operation performed by a respective functional element. | 04-22-2010 |
20100146023 | SHIFTER WITH ALL-ONE AND ALL-ZERO DETECTION - A shifter that includes a plurality of shift stages positioned within the shifter, and receiving and shifting input data to generate a shifted result, and a detection circuit coupled at an input of a final shift stage of the plurality of shifters, in a final stage within the shifter. The detection circuit receives a partially shifted vector at the input of the final shift stage along with a predetermined shift amount, and performing an all-one or all-zero detection operation using a portion of the partially shifted vector and the predetermined shift amount, in parallel, to a shifting operation performed by the final shift stage to generate the shifted result. | 06-10-2010 |
20100174764 | REUSE OF ROUNDER FOR FIXED CONVERSION OF LOG INSTRUCTIONS - A method for converting a signed fixed point number into a floating point number that includes reading an input number corresponding to a signed fixed point number to be converted, determining whether the input number is less than zero, setting a sign bit based upon whether the input number is less than zero or greater than or equal to zero, computing a first intermediate result by exclusive-ORing the input number with the sign bit, computing leading zeros of the first intermediate result, padding the first intermediate result based upon the sign bit, computing a second intermediate result by shifting the padded first intermediate result to the left by the leading zeros, computing an exponent portion and a fraction portion, conditionally incrementing the fraction portion based on the sign bit, correcting the exponent portion and the fraction portion if the incremented fraction portion overflows, and returning the floating point number. | 07-08-2010 |
20110320512 | Decimal Floating Point Mechanism and Process of Multiplication without Resultant Leading Zero Detection - A decimal multiplication mechanism for fixed and floating point computation in a computer having a coefficient mechanism without resulting leading zero detection (LZD) and process which assumes that the final product will be M+N digits in length and performs all calculations based on this assumption. Least significant digits that would be truncated are no longer stored, but retained as sticky information which is used to finalize the result product. Once the computation of the product is complete, a final check based on the examination of key bits observed during partial product accumulation is used to determine if the final product is truly M+N digits in length, or M+N−1 digits. If the latter is true, then corrective final product shifting is employed to obtain the proper result. This eliminates the need for dedicated leading zero detection hardware used to determine the number of significant digits in the final product. The corrective final product shifting also incorporates adjustments to the coefficient of the product when the product's exponent is at its extremes and the final product must be brought to be within the precision and range of a given format. | 12-29-2011 |
20130173681 | Range Check Based Lookup Tables - Mechanisms for utilizing a reduced lookup table circuit to perform an operation in a data processing device are provided. A first input value is input for selecting a subset of values from the reduced lookup table circuit. The reduced lookup table circuit stores only boundary cell values from a fully filled lookup table corresponding to the reduced lookup table circuit. The subset of values comprises only a subset of boundary cell values corresponding to the first input value. A second value is input and a comparison, by the reduced lookup table circuit, of the second value to each of the boundary cell values in the subset of boundary cell values is performed. The reduced lookup table circuit outputs an output value based on results of the comparison of the second value to each of the boundary cell values in the subset of boundary cell values. | 07-04-2013 |
20130173683 | Range Check Based Lookup Tables - Mechanisms for utilizing a reduced lookup table circuit to perform an operation in a data processing device are provided. A first input value is input for selecting a subset of values from the reduced lookup table circuit. The reduced lookup table circuit stores only boundary cell values from a fully filled lookup table corresponding to the reduced lookup table circuit. The subset of values comprises only a subset of boundary cell values corresponding to the first input value. A second value is input and a comparison, by the reduced lookup table circuit, of the second value to each of the boundary cell values in the subset of boundary cell values is performed. The reduced lookup table circuit outputs an output value based on results of the comparison of the second value to each of the boundary cell values in the subset of boundary cell values. | 07-04-2013 |