Automating WCET analysis for DO-178B/C | page 3
Introduction
Determination of worst-case execution time (WCET) is an
activity that is recommended in DO-178B and DO-178C
6.3.4f. Here we consider the current state of practice for
determining WCET and present the benefits available from
automating the process. Thanks to its DO-178B/DO-330
qualification pack, RapiTime uniquely allows these benefits
to be realised in DO-178B/C projects.
RapiTime is a tool to
determine the
execution time of
embedded software.
It reports measured
maximum, high-
water-mark and
calculated worst-
case times. The
WCET calculation is
based on measured
data, annotations
and the source code
structure.
To use RapiTime’s
calculated WCET in
support of DO-178B
or DO-178C
objective 6.3.4f, it is
necessary both to
qualify the tool and
to provide a
corresponding
analysis process.
What is RapiTime?
One approach to determining WCET
that is widely used and currently
accepted by certification authorities is
manual analysis and measurement.
Manual analysis and measurement is
an effort-intensive task and requires an
extremely high level of care to ensure
measurements are correctly captured.
By using automation to reduce the
level of effort required and increase the
accuracy of results, RapiTime represents
an evolution of the manual analysis
and measurement approach. With the
introduction of the DO-178B/DO-330
qualification pack, RapiTime can
replace manual activities in projects
requiring DO-178B/DO-178C certification.
The development of the new qualification
pack means RapiTime is the only
tool in the marketplace capable of
measurement-based WCET analysis
for DO-178B.
In this document we describe:
■ What is required for WCET in
DO-178B projects.
■ The current state of practice, and its
limitations.
■ How RapiTime represents an
improvement on the state of practice.
■ How to use RapiTime in a DO-178B
environment.
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