Evaluation Environment for AUTOSAR-Autocode in Motor Control ...

2.4 Basic Concepts
by the owning task. If the task waits for an event and the event is set from another
routine, the task will switch into the state “ready”. At the beginning of an extended
task, that means at the transition from “suspended” to “ready”, all events of this task
will be cleared from the operating system.
2.3.3 Resources
The resources of the operating system provide mutual exclusive access of tasks with
different priorities to shared resources. If a task occupies a resource, no other task can
do the same. So the task have to wait until the resource is released. That this waiting
cannot only be done in an extended task, the priority ceiling protocol is used. This
protocol increases the priority of the task that occupies a resource. This is done during
the time, the resource is accessed. The priority is increased to the highest priority of
all tasks that can also access this resource. So it is prevented that another task, which
can also access the resource, runs during this time.
2.4 Basic Concepts
Some basic concepts and terms are now described in more detail. They are necessary
for this work and to understand the RTE and the generating of the RTE. This description
is based on the documents [6, 7, 3]. The second document is a specification
of the VFB for release 3.0, because a version of this document for 2.1 does not exist.
However, it contains the same mechanisms as release 2.1 and something more that is
not used here.
2.4.1 Types
To use data types in the software and especially with AUTOSAR mechanisms like the
communication, this data types have to be specified. The simplest types that can be
specified are the primitive types, which can be integers, strings, characters or Boolean
types. This types are additionally specified with a range (or a length for strings), that
says which values are possible. Existing types can be combined to composite data
types, which are an array or a record.
2.4.2 Ports
Ports are the mechanism of software components to communicate between each other.
They define interaction points of a SWC. Several kinds of ports are distinguished. A
port is either a required port or a provided port. A provided port offers data elements
or services, a required port is the counterpart, which uses the data elements or services.
This distinction describes the direction of the communication. Another classification is
the kind of the communication, which is divided into sender–receiver and client–server
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