Abstract: An apparatus and method for calculating a square root of an operand in a microprocessor are provided. The microprocessor has a plurality of square root instructions, each of which specifies a square root calculation precision. The apparatus includes translation logic and execution logic. The translation logic decodes the square root macro instruction into a plurality of prescribed-precision machine instructions according to the square root calculation precision specified by the plurality of square root instructions. The execution logic, coupled to the translation logic, receives the plurality of prescribed-precision machine instructions and calculates the square root of the operand according to the specified square root calculation precision. At least one of the plurality of square root instructions specifies the square root calculation precision such that less significant bits are calculated in the square root than are provided in the operand.

Abstract: A microprocessor is provided having selective control features to determine its core-to-bus clock ratio. The microprocessor includes a fuse and buffer/control logic. The fuse, fabricated on the microprocessor's metalization or poly layer, can be blown with a laser during fabrication. When blown, the fuse provides a permanent state that prescribes a fixed core-to-bus clock ratio. The buffer/control logic is coupled to the fuse. The buffer/control logic accepts the permanent state and directs the microprocessor to set the core-to-bus clock ratio to a fix value, thus disabling control of the core-to-bus clock ratio via external clock ratio control signals.

Abstract: An apparatus and method for exchanging operands within a microprocessor is provided. The apparatus contains a translator for generating a micro instruction that loads a first operand into a second location, and a second operand into a first location without specifying intermediate storage of either operand. In addition, interlock control is provided to disable interlock delay when executing an exchange instruction. Disabling the interlock control allows an exchange operation to be performed in 2 or less clock cycles. Also, a register file is used that allows two operands to be written to it in parallel. Operand write control is used with the register file to switch the operand specifiers in an exchange instruction during write back, to allow the specifiers used to retrieve operands from the register file to also be used for the exchange.

Abstract: An apparatus and method for improving the execution of floating point instructions in a microprocessor is provided. During decode of a floating point instruction, translation logic generates absolute addresses of specified registers in a floating point register file. These absolute references, as opposed to relative references to a top-of-stack, are inserted into associated micro instructions. In the event of an exception, synchronization logic provides an architected top-of-stack for the floating point instruction associated with the exception to the translation logic so that subsequent instructions will properly reference floating point registers.

Abstract: A method for improving the execution of significant bit scans on a data entity in a computer system is provided. The data entity is examined in a number of iterations equal to the base two logarithm of the size of the data entity in bits, N. Initially, half of the data entity is examined to determine if the significant bit is present. If not, the other half of the data entity is examined. The half within which the significant data entity resides is then iteratively halved and examined in each successive iteration of the method until the number of bits examined is equal to one.