Square root digit recurrence
AssigneeArm Limited
InventorsJavier Diaz Bruguera, David M. Russinoff
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Abstract
A data processing apparatus is provided, for performing a digit-recurrence square root operation on an input value. Receiver circuitry receives a remainder value of a previous iteration of the digit-recurrence square root operation. Comparison circuitry compares most significant bits of the remainder value of the previous iteration with a number of selection constants, in order to output a next digit of a result of the digit-recurrence square root operation. The comparison circuitry compares at most 3 fractional bits of the remainder value of the previous iteration with the plurality of selection constants.
Claims12
A data processing apparatus to perform a digit-recurrence square root operation on an input value, comprising:
- receiver circuitry to receive a remainder value of a previous iteration of said digit-recurrence square root operation, and a partial result of said digit-recurrence square root operation from a previous iteration;
- and
- comparison circuitry comprising comparators configured to communicate with said receiver circuitry and to compare most significant bits of said remainder value of said previous iteration of said digit-recurrence square root operation with a plurality of selection constants of said digit-recurrence square root operation, to output a next digit of a result of said digit-recurrence square root operation,
- said comparison circuitry further comprising selection circuitry to select one of a plurality of subsets of said plurality of selection constants to compare to a predetermined number of fractional bits of said remainder value based on most significant bits of said partial result of said digit-recurrence square root operation from a previous iteration;
- and
- storage circuitry, accessible to said selection circuitry, to store said plurality of selection constants of said digit-recurrence square root operation, wherein:
- said most significant bits of said remainder value comprise said predetermined number of fractional bits,
- said predetermined number is at most 3, and
- said selection constants comprise at most 3 fractional bits
- said comparison circuitry comprises deviation circuitry to replace a single selection constant in said one of said plurality of subsets in response to a current iteration of said digit-recurrence square root operation being a predetermined iteration.
A data processing method for performing a digit-recurrence square root operation on an input value, comprising:
- receiving, by receiver circuitry, a remainder value of a previous iteration of said digit-recurrence square root operation, and a partial result of said digit-recurrence square root operation from a previous iteration;
- comparing, by comparison circuitry including comparators communicating with said receiver circuitry, most significant bits of said remainder value of said previous iteration of said digit-recurrence square root operation with a plurality of selection constants of said digit-recurrence square root operation, to output a next digit of a result of said digit-recurrence square root operation;
- selecting, by selection circuitry included the comparison circuitry, one of a plurality of subsets of said plurality of selection constants to compare to a predetermined number of fractional bits of said remainder value based on most significant bits of said partial result of said digit-recurrence square root operation from a previous iteration;
- and
- storing, by storage circuitry accessible to said selection circuitry, said plurality of selection constants of said digit-recurrence square root operation, wherein:
- said most significant bits of said remainder value comprise said predetermined number of fractional bits,
- said predetermined number is at most 3,
- said selection constants comprise at most 3 fractional bits, and
- said step of comparing comprises replacing a single selection constant in said one of said plurality of subsets in response to a current iteration of said digit-recurrence square root operation being a predetermined iteration.
Dependencies are inferred from the claim text.