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Double Double Operation Using Multiply-Addition Dataflow

IP.com Disclosure Number: IPCOM000039842D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01

Publishing Venue

IBM

Related People

Authors:
Desrosiers, DP Montoye, RK [+details]

Abstract

A technique is described whereby the Multiply-ADdition (M.A.D.) dataflow is used to perform double double operations, such as D = (A,B) + C, where A, B and C are 56-bit numbers. The double _ double operation is an addition to the M.A.D.dataflow concept discussed in the article on pages 982-987. First, the two Booth encoder inputs will be A and a true "1" number, i.e., 56 "1". All the Booth coefficients will be null except the last one, bits 55 and 56, which will be -1. Using a "classical" Booth encoder, a "0" is forced by setting the EXT signal, as shown in Fig. 1, to "1". The 20 term, called the 29th term, is 20 * A = A. Therefore, the 29 terms out by the Booth encoder will be: (Image Omitted) Secondly, using the dataflow as shown in Fig.