CHISSA Demonstration Facility

This tool is being presented as a part of the CHISSA DEMONSTRATION FACILITY. NIST/CHISSA does not assume any responsibility for any inaccuracies found in this tool or information presented by this tool. In no case does demonstration of a tool or use of trade names associated with it, imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the products are necessarily the best available for the purpose.

Unravel Information

Name: Unravel
Description:
Unravel is a Computer Aided Software Engineering (CASE) tool, for software written in ANSI C. Unravel can assist evaluation of high integrity software by using program slices to extract computations for examination.
Documentation:
NISTIR 5691: A CASE Tool to Assist Evaluation of High Integrity Software . This publication includes a description of unravel's requirements, design and use.
Source:
A copy of the source code is available. It requires a UNIX or POSIX environment, an ANSI C compiler and the MIT X Window System, version 11 release 5 or later.
More Information:
Jim Lyle
National Institutes of Standards and Technology
Computer Systems Laboratory
Building 255, Room B266
Gaitherburg, MD 20899
Phone: 1-301-975-3270
Fax: 1-301-926-3696
Email: jlyle@nist.gov
You are the person to see this demonstration.

Unravel Demonstration

An informal definition of a program slice taken at statement n on variable v is all statements that might affect the value that v has just before control reaches statement n.

Unravel's value can help a reviewer to understand the logic flow of the program being examined.

The program unravel contains three main components: the Analyzer, which is a preprocessor to convert ANSI C source code into a language independent format (LIF); the Linker, which merges LIF codes taken from multiple source files; and the Slicer which performs the slices of variables.

In this demonstration, we will show how to prepare and compute program slices for a sample program.

Unravel is an X Windows based tool. Because not every person accessing this demo has a computer running X Windows, there are two versions of this demonstration.

  1. One for those who are accessing it from a computer running X Windows.
  2. One for those who are accessing it from any other system.
If you are not using X Windows, click here to begin the demonstration. If you are using X Windows, please input your X display name here and then press the submit button. (An X display name will look something like site.com:0. If you are unsure of what your display name is, you might try typing printenv DISPLAY to your Unix based system, or ask your system administrator. You may also need to allow our X-server to connect to your X-server, to do this execute the following command xhost +hissa.ncsl.nist.gov) Shortly after you press the submit button, the Unravel control panel will appear on your screen and you'll be ready to proceed with the demonstration.