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Method for Table Search Processing

IP.com Disclosure Number: IPCOM000081925D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Tobias, RL: AUTHOR

Abstract

This table searching process is a simple but efficient machine-independent method for coding a table search in which the search argument is not known to exist in the table, such as is sometimes encountered during source character string syntax checking. The method is valid, in terms of efficiency, in either a structured or a nonstructured programming environment, and is demonstrated here using assembler language for the IBM System/7.

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Method for Table Search Processing

This table searching process is a simple but efficient machine-independent method for coding a table search in which the search argument is not known to exist in the table, such as is sometimes encountered during source character string syntax checking.

The method is valid, in terms of efficiency, in either a structured or a nonstructured programming environment, and is demonstrated here using assembler language for the IBM System/7.

This method is based on the use of the search argument to operate also as an end-of-table delimiter, eliminating the requirement for a separate end-of-table test. An entry position is reserved at the end of the usual table, and the argument is stored in this terminal position before execution of the search loop. The table is thus guaranteed to contain the search argument. Since the search begins with the first table entry, the first encountered argument-entry match (whether occurring within the valid entry section of the table or at the terminal entry position) always ends the search loop.

In the following example, a source character (x) coupled with a blank character (b) has previously been stored at location CHAR in the format `xb'. This search argument is moved to table guard position TEND, table entry pointer REG5 is initialized, and a 4-instruction search loop is executed. Should the search argument be valid (e.g., `*b') then the associated function processor (FMUL) is executed. An invalid sear...