Digital division device and method using a reduced-sized lookup table
AssigneeSeagate Technology LLC
InventorsTravis E. Ell, John C. Morris
Life of this patent
Estimating the term…
Abstract
Devices and methods are provided for estimating a high-precision quotient using a smaller-than-conventional lookup table. The devices include a numerator register feeding a numerator value (as a succession of bits or words) into a forward signal path. The forward path includes a partial quotient generator, an accumulator, and a latch. The devices further include a feedback signal path emerging from the latch output, undergoing division by bit-shifting, and terminating as an input to the accumulator. A multiple divide implementation for use in a particular servo control system is also presented.
Claims12
A device for estimating a quotient of a numerator and a denominator, comprising:
- a numerator register able to provide successive portions of the numerator;
- a denominator register operatively able to provide the denominator;
- a partial quotient generator (PQG) operatively coupled to the registers and able to receive the portions and the denominator and to generate a succession of signals indicative of portions of the quotient;
- an accumulator having a first input port, a second input port, and an output, the first input port operatively coupled to the PQG and able to receive the signals;
- a latch operatively coupled to the output of the accumulator so as to receive accumulated values;
- and
- a shifter operatively coupled to the latch so as to receive latched values, the shifter also operatively coupled to the accumulator's second input port so as to feed back shifted latched values to the accumulator.
A disc drive comprising:
- a rotatable disc include a plurality of tracks, each track having a plurality of servo position fields;
- a controllably positionable head adjacent the disc which reads the servo position fields to provide servo burst signals indicative of relative position of the head with respect to the servo position fields;
- and
- a servo processor including the device of claim 4 operably coupled to the head to receive the burst signals and derive therefrom the numerator and denominator, the processor configured to generate a head control signal from the estimated quotient.
A device for estimating a quotient of a numerator and a denominator, comprising:
- a forward signal path comprising a partial quotient generator (PQG), an accumulator, and a latch having a synchronous input, the PQG configured to generate a succession of signals indicative of portions of the quotient;
- a feedback signal path comprising a reducing bit shifter, the feedback path operatively coupled to receive the portions and to provide reduced portions to the accumulator;
- a denominator register operatively coupled to provide the denominator to the PQG;
- a numerator register having a synchronous input, configured to provide successive portions of the numerator to the PQG;
- and
- a controller operatively coupled to each of the synchronous inputs.
A device for estimating a quotient of a numerator and a denominator comprising:
- two multi-bit registers configured for receiving and outputting the denominator, and for receiving and outputting the numerator in successive portions;
- and
- means for receiving the denominator and the successive portions of the numerator and generating therefrom an estimate by iterative calculation.
A method for generating an estimated quotient value from a numerator value and a denominator value, comprising:
- electronically storing the numerator value and the denominator value as multi-bit representations in a memory;
- parsing the numerator value into a series of portions including a least significant (LS) portion and a next-least significant (NLS) portion each comprising at least one bit;
- electronically transmitting the LS portion and the denominator value to a partial quotient generator (PQG) which utilizes a lookup table to output a first partial quotient value comprising a multi-bit representation of a quotient of the LS portion and the denominator value;
- electronically transmitting the NLS portion to the PQG which utilizes the lookup table to output a second partial quotient value comprising a multi-bit representation of a quotient of the NLS portion and the denominator value;
- and
- using an accumulator to generate the estimated quotient value as a multi-bit representation in relation to the first and second partial quotient values.
Dependencies are inferred from the claim text.