General purpose computer program for access and use of alternate library file with minimum programming effort by user is described. Manner in which program is implemented after determining external requirements is analyzed. Program was developed for use with CDC-6400 computer

Drozdowski, J. M.

English

NASA Technical Reports Server

October 1972	 B72-10607 
NASA TECH BRIEF 
Langley Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Automatic Computer Subprogram Selection From Application-

Program Libra nes-ALTLIB 
The problem: 
Modular programming techniques are currently in 
widespread use in the development of scientific and 
engineering computer programs at the NASA Langley 
Research Center. These techniques involve the develop-
ment of frequently used algorithms into modular (sub-
program) form and the collection of application modules 
supporting a particular area into an application-oriented 
library. This library can then be employed repeatedly by 
programmers working in the same area of application 
to simplify new-program development. 
A major problem, however, for people maintaining 
their own application-oriented library is the complex-
ity and volume of control-card programming that must 
be performed to achieve subprogram selection. 
The solution: 
A general-purpose program that enables access and 
use of an alternate library file with minimum pro-
gramming effort by the user was developed. 
How it's done: 
The program is used, prior to loading, to select and 
combine required subprograms from an alternate library 
file with the user's object file. It employs the user's 
program field length and is called into operation by a 
control card. The program structure that the user pro-
gram can utilize includes overlay or segmentation. 
ALTLIB is a general-purpose program that automates 
the subprogram selection process. ALTLIB analyzes the 
user's program to determine all external requirements; 
ALTLIB then proceeds to select from the alternate 
library file all subprograms that a user's program requires. 
The selected subprograms and the user's object file are 
then merged onto a file designated by the user for sub-
sequent loading and execution. 
Notes: 
1. This program was developed for the CDC-6400 com-
puter, Scope 3.2, but should be usable on any 6000 
series computer. The program is programmed in 
FORTRAN IV (53%) and COMPAS (4717o). 
2. Inquiries concerning this program should be directed 
to:
COSMIC 
112 Barrow Hall 
University of Georgia 
Athens, Georgia 30601 
Reference: LAR-1 1124 
Source: Joseph M. Drozdowski 
Langley Research Center 
(LAR-1 1124) 
Category 09 
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	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
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Automatic computer subprogram selection from application-program libraries - ALTLIB

The program ALTLIB (ALTernate LIBrary) which allows a user access to an alternate subprogram library with a minimum effort is discussed. The ALTLIB program selects subprograms from an alternate library file and merges them with the user's program load file. Only subprograms that are called for (directly or indirectly) by the user's programs and that are available on the alternate library file will be selected. ALTLIB eliminates the need for elaborate control-card manipulations to add subprograms from a subprogram file. ALTLIB returns to the user his binary file and the selected subprograms in correct order for a call to the loader. The user supplies the alternate library file. Subprogram requests which are not satisfied from the alternate library file will be satisfied at load time from the system library

Automatic computer subprogram selection from application-program libraries - ALTLIB

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