Processing unit having decimal floating-point divider using Newton-Raphson iteration
First Claim
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1. A method comprising:
- receiving a decimal floating-point dividend and a decimal floating-point divisor with a decimal floating-point divider; and
performing Newton-Raphson iterations with the decimal floating-point divider to output a decimal floating-point quotient.
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Abstract
A decimal floating-point divider is described that implements efficient hardware-based techniques for performing decimal floating-point division. The divider uses an accurate piecewise linear approximation to obtain an initial estimate of a divisor'"'"'s reciprocal. The divider improves the initial estimate of the divisor'"'"'s reciprocal using a modified form of Newton-Raphson iteration. The divider multiplies the estimated divisor'"'"'s reciprocal by the dividend to produce a preliminary quotient. The preliminary quotient is rounded to produce the final decimal floating-point quotient.
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Citations
34 Claims
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1. A method comprising:
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receiving a decimal floating-point dividend and a decimal floating-point divisor with a decimal floating-point divider; and
performing Newton-Raphson iterations with the decimal floating-point divider to output a decimal floating-point quotient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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receiving a decimal dividend and a decimal divisor with a decimal floating-point divider;
accessing a lookup table to retrieve a decimal coefficient using a portion of the divisor as an index into the lookup table;
computing an initial approximation of the divisor'"'"'s reciprocal based on the coefficient;
iteratively computing an improved estimate of the divisor'"'"'s reciprocal with the decimal floating-point divider;
multiplying the dividend by the improved approximation of the divisor'"'"'s reciprocal to produce a preliminary decimal quotient;
computing a biased decimal quotient from the preliminary decimal quotient; and
outputting a decimal quotient based on the biased decimal quotient. - View Dependent Claims (11, 12)
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- 13. A processing unit comprising a decimal floating-point divider that performs Newton-Raphson iterations to output a decimal floating-point quotient.
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32. A decimal floating-point divider comprising:
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inputs to receive a decimal floating-point dividend and a decimal floating-point divisor;
a nine'"'"'s complement block;
a decimal multiplier;
wherein the nine'"'"'s complement block and the decimal multiplier compute an initial approximation of the divisor'"'"'s reciprocal, wherein the decimal multiplier further (a) performs Newton-Raphson iterations to compute an improved approximation of the divisor'"'"'s reciprocal based on the initial approximation, and (b) multiplies the dividend by the improved approximation to produce a preliminary decimal quotient, and (c) performs an adjustment to the preliminary decimal quotient to produce a biased decimal quotient, and (d) multiplies the divisor by the biased decimal quotient to generate signals for rounding and correction; and
a processing unit to output a decimal floating-point quotient based on the biased decimal quotient. - View Dependent Claims (33, 34)
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Specification