Browse Prior Art Database

Use of the Cipher in Program Analysis

IP.com Disclosure Number: IPCOM000080501D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bouricius, WG: AUTHOR [+2]

Abstract

The use of the cipher, or two-sided algebraic zero, to represent nonnumbers will enable the analysis and debugging of computer programs to be simplified and speeded up.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 92% of the total text.

Page 1 of 1

Use of the Cipher in Program Analysis

The use of the cipher, or two-sided algebraic zero, to represent nonnumbers will enable the analysis and debugging of computer programs to be simplified and speeded up.

Where the result of an arithmetic operation is undefined (for example, the result of dividing an integer by zero), it can be represented by the cipher. All logical, relational and arithmetic operations (other than "equals") in which the cipher is an argument will yield the cipher as a result. Equality between ciphers yields the number 1, representing truth.

In present computer systems, the occurrence of a condition which would result in the cipher causes an interrupt and invokes a remedial software routine, inasmuch as the cipher is not represented in the notation of such systems. However, if the cipher were represented by a distinctive bit pattern, then it could be handled by hardware in a faster and cheaper manner than is done at present in software. Furthermore, by not suppressing the conditions that yielded the cipher results, the system could preserve a record of those conditions for more comprehensive analysis at a later and more convenient time.

It is proposed herein to preempt a particular bit pattern that presently is handled as an exception by most computer systems, and employ it to represent the cipher. The bit pattern suggested for this purpose is 1 followed by all 0's, which represents the largest negative integer and also the negative floating-po...