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# Nonsymmetrical Feedback Algorithm

IP.com Disclosure Number: IPCOM000088807D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 12K

IBM

## Related People

Reddi, UP: AUTHOR

## Abstract

The method described herein allows one to determine nonsymmetrical feedback paths in a given set of microsequential logic. As used herein, a circular path containing three or more unique nets is characterized as a nonsymmetrical feedback path. To determine such feedback paths, one must consider all of the possible paths of each net.

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Nonsymmetrical Feedback Algorithm

The method described herein allows one to determine nonsymmetrical feedback paths in a given set of microsequential logic. As used herein, a circular path containing three or more unique nets is characterized as a nonsymmetrical feedback path. To determine such feedback paths, one must consider all of the possible paths of each net.

To insure that every path is considered once and only once, a check vector of the same length as the number of unique nets is established which will initially contain all zeroes. For each path considered for the nets spanning this path, a "0" in the check vector is changed to a "1". When all of the paths have been considered, the check vector will contain only ones. The search for nonsymmetrical feedback paths becomes bounded in that once a "1" appears in the given net for the check vector, corresponding paths in which this net is an element need not be reconsidered. The problem is further bounded in that once a feedback loop is recognized, a "1" is automatically placed in the appropriate place of the check vector, regardless of other possible paths within that net.

The nonsymmetrical feedback algorithm comprises the following steps: 1. Give each unique net in the given logic function a positive decimal integer number same as its position in the alphanumeric ordering with the other nets. 2. Find sinks of each net. 3. Initialize check vector to zeroes. 4. Pickup an unprocessed net and check whether it...