摘要:
An apparatus, a method and a computer program are provided to reduce leakage current in a processor. Traditionally, extra logic is employed to reduce leakage currents. However, reducing leakage current without sacrificing fine grain operations and speed can be difficult. Achieving such a goal can be accomplished by incorporating a multiplexer (mux) into the scan-in path of scan registers so that units or sub-units of the processor can be powered down individually. Additionally, the muxes are not incorporated into time paths, so speed can be preserved.
摘要:
A disclosed byte execution unit receives byte instruction information and two operands, and performs an operation specified by the byte instruction information upon one or both of the operands, thereby producing a result. The byte instruction specifies either a count ones in bytes operation, an average bytes operation, an absolute differences of bytes operation, or a sum bytes into halfwords operation. In one embodiment, the byte execution unit includes multiple byte units. Each byte unit includes multiple population counters, two compressor units, adder input multiplexer logic, adder logic, and result multiplexer logic. A data processing system is described including a processor coupled to a memory system. The processor includes the byte execution unit. The memory system includes a byte instruction, wherein the byte instruction specifies either the count ones in bytes operation, the average bytes operation, the absolute differences of bytes operation, or the sum bytes into halfwords operation.
摘要:
An apparatus 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.
摘要:
The present invention provides for calculating a shift amount as a function of a plurality of numbers. At least one decoder and the at least one adder are coupled in parallel. A shifter is configured to compute a value in a plurality of shift stages, and wherein a bit group of the shift amount is employable to affect at least one of the plurality of shift stages, thereby decreasing processing time.
摘要:
A disclosed byte execution unit receives byte instruction information and two operands, and performs an operation specified by the byte instruction information upon one or both of the operands, thereby producing a result. The byte instruction specifies either a count ones in bytes operation, an average bytes operation, an absolute differences of bytes operation, or a sum bytes into halfwords operation. In one embodiment, the byte execution unit includes multiple byte units. Each byte unit includes multiple population counters, two compressor units, adder input multiplexer logic, adder logic, and result multiplexer logic. A data processing system is described including a processor coupled to a memory system. The processor includes the byte execution unit. The memory system includes a byte instruction, wherein the byte instruction specifies either the count ones in bytes operation, the average bytes operation, the absolute differences of bytes operation, or the sum bytes into halfwords operation.
摘要:
A preferred embodiment of the present invention provides a method, computer program product, and processor design for supporting 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, a preferred embodiment of the present invention incurs significantly less overhead than would specialized hardware, while still maintaining a uniform FPU latency, which allows for much simpler control logic.
摘要:
An apparatus, a method, and a computer program are provided for fully utilizing a double precision Floating Point (FP) alignment shifter. In conventional FP adders, and other FP computational units, double precision FP alignment shifters are utilized to perform both double and single precision alignment shifts. However, when a conventional double precision FP alignment shifter is utilized for a single precision calculation, half of the available capacity of the double precision FP alignment shifter is wasted. Therefore, to better utilize the capacity of double precision FP alignment shifter, a modified alignment shifter is utilized that can perform either an alignment shift for a double precision calculation or two simultaneous (or nearly simultaneous) alignment shifts for two single precision calculations.
摘要:
A method, a computer program, and an apparatus are provided to protect transmission gates in a multiplexer (mux). Because transmission gates are much faster than the more convention AND-OR arrays, transmission gate usage in muxes are being used more often in high speed circuitry. However, transmission gate have a significant problem in that short circuit are possible for situations where there is not a one-hot select signal. Therefore, to eliminate the problem, logic gates are utilized specifically during Power-On Reset (POR) to force a one-hot selection to prevent any possible short circuits.
摘要:
An apparatus and computer program product are provided for improving a high-speed adder for Floating-Point Units (FPU) in a given computer system. The improved adder utilizes a compound incrementer, a compound adder, a carry network, an adder control/selector, and series of multiplexers (muxes). The carry network performs the end-around-carry function simultaneously to and independent of other required functions optimizing the functioning of the adder. Also, the use of a minimum number of muxes is also utilized to reduce mux delays.
摘要:
A method, an apparatus, and a computer program are provided to more efficiently generate a sticky bit in a Floating Point Design. Traditionally, separate ORing logic or OR trees were employed to compress the stick outputs of a normalization shifter into at least one sticky bit. However, this design has power consumption and area costs associated with it. To overcome these disadvantages, the OR trees of Leading Zero Counters (CLZs) are employed in conjunction with the Edge Vector logic of a Leading Sign Anticipator and an additional OR gate to determine the sticky bit.