Digit-Recurrence Algorithm for Computing Reciprocal Square-Root

Naofumi TAKAGI  Daisuke MATSUOKA  Kazuyoshi TAKAGI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E86-A   No.1   pp.221-228
Publication Date: 2003/01/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: VLSI Design Technology and CAD
computer arithmetic,  reciprocal square-root,  hardware algorithm,  digit-recurrence,  computer graphics,  

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A digit-recurrence algorithm for computing reciprocal square-root which appears frequently in multimedia and graphics applications is proposed. The reciprocal square-root is computed by iteration of carry-propagation-free additions, shifts, and multiplications by one digit. Different specific versions of the algorithm are possible, depending on the radix, the redundancy factor of the digit set, and etc. Details of a radix-2 version and a radix-4 version and designs of a floating-point reciprocal square-root circuit based on them are shown.