Content
- 1 Introduction
- 2 Notation
- 3 Tool Usage
- 4 Top Level Elements
- 5 Control Flow Elements
- 6 Data Flow Elements
- 7 Location Attributes
- 8 Loop Bound Attributes
- 9 Time and Execution Attributes
- 10 Control Flow Properties
- 11 Control Flow Constraints
- 12 Data Flow Properties
- 13 Data Flow Constraints
- 14 Future Developments
- 15 Appendix A: FFX Grammar
- 16 Appendix B: Example – output of oRange tool
1 Introduction
FFX (Flow Fact in XML) is an XML-based file format used to represent flow facts. Flow facts are used in WCET (Worse Case Execution Time) tools used to verify the real-time systems. Such information is used either to help to achieve the computation, or to exhibit WCET in particular situations.
Main concepts that have driven the design and the development of FFX includes:
freedom – tools using FFX does not have to support all features what, at worse, may only induce a loss of precision,
extensibility – the use of XML allows to easily insert new elements or new attributes without breaking the compatibility with other tools,
soundness – all provided information must be ruled by a precision order ensuring that, at least, information in most generic cases must not be more precise than in particular cases.
These properties should ensure a maximum of usability for FFX.
This document describes the version 1.0 of FFX that may be separated in:
location information that identify the code parts the information apply to and when they apply during the execution of the program,
flow information that are used to perform the WCET computation (for example, loop bounds, range of varibale, etc).
The following standard documents applies to the description of FFX: