×

Reciprocal generator using piece-wise-linear segments of varying width with floating-point format

  • US 6,260,054 B1
  • Filed: 10/29/1998
  • Issued: 07/10/2001
  • Est. Priority Date: 10/29/1998
  • Status: Expired due to Term
First Claim
Patent Images

1. A reciprocal generator comprising:

  • an input bus;

    a leading-zero detector, coupled to the input bus, for generating a scale factor indicating a number of leading zeros of an input value on the input bus;

    wherein the leading-zero detector is coupled to only upper bits of the input bus and not connected to lower bits of the input bus;

    a shifter, responsive to the leading-zero detector, for shifting the input bus by a number of bit-positions indicated by the leading-zero detector to produce a shifted input;

    a lookup table, coupled to the shifter, having a plurality of entries, each entry having an initial reciprocal field and a slope field, the lookup table for outputting an initial reciprocal and a slope for an entry selected by a portion of the shifted input; and

    an interpolator, coupled to the lookup table, for generating a reciprocal base from the initial reciprocal and the slope output by the lookup table, wherein the reciprocal of the input bus is the reciprocal base from the interpolator scaled by the scale factor from the leading-zero detector, wherein the input bus has an input range, the input range being divided into a plurality of sections;

    wherein the lookup table does not have separate entries for each of the plurality of sections, the lookup table having entries for a last section, the last section having largest input values, whereby the reciprocal is generated from the lookup table and the scale factor from the leading-zero detector and entries for the last section but not all sections are stored in the lookup table and the leading-zero detector detects a limited number of leading zeros.

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×