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Arithmetic Algorithm for Determining Computer Program Execution Sequences

IP.com Disclosure Number: IPCOM000088226D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Thomas, DR: AUTHOR

Abstract

This algorithm "records", via a simple arithmetic computation, the logical path followed by a computer program. Hence, numerical data concerning program sequences may be obtained (e.g., the order in which modules are "called" during input/output operations), and faults detected (if the failure alters the sequences).

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Arithmetic Algorithm for Determining Computer Program Execution Sequences

This algorithm "records", via a simple arithmetic computation, the logical path followed by a computer program. Hence, numerical data concerning program sequences may be obtained (e.g., the order in which modules are "called" during input/output operations), and faults detected (if the failure alters the sequences).

More precisely, suppose that there are n events (e.g., module "calls" or procedure "openings") which may or may not occur during program execution. An algorithm will be given which determines after the fact, the order in which these events actually occurred (possibly with some occurring more than once or not at all).

With each event, "associate" a unique positive integer (e.g., when the events are procedure openings, association could be via a table to be used by the executive program). Let m be any integer strictly greater than all of the aforementioned integers (e.g., if the events are denoted by E(1), E(2),..., E(n), associate i with E(i) and let m = n+1). An integer P shall now be computed based upon the order of occurrence of some of these events.

Initially, let P = 0. Upon the occurrence of an event, replace P by Pm+a, where "a" is the integer previously associated with that event. Notice that after k> or = 1 events have occurred, P is given by the following expression: (1) P = a(k) + a(k-1)m + a(k-2)m/2/ + ... + a(i)m/-i/ + ... + a(1)m/k-1/. where a(i) denotes the integer...