Embedded Software for SoC - Grupo de Mecatrônica EESC/USP

Exploring SW Performance 101
operation through a channel. Each encapsulated operation is called in two
steps, the first step is the decode phase to identify the serving slave
operation, and then the invocation of the operation through the channel.
This invocation adds new parameters to the slave operation which configures
the channel transactions to be generated. Note that a master access
only addresses a single channel, and that it can invocate a subset of the
operations of several slaves, so that it has its own interface which may
differ from the union of the slaves interfaces and doesn’t require to be an
explicit sc_interface.
2.1.2. Communication refinement
Defining the accesses module is very straight forward. They follow a simple
pattern. This is why our tool is able of generating the accesses code with
very little configuration information once the communication channel is
chosen. Figure 8-3 shows the example of accesses to a bus communication
channel. It combines UML class diagrams to describe modules and
SystemC2.0 [6] graphical notation for ports and interfaces. Furthermore a
graphical notation has been introduced to stereotype the accesses modules. It
can be used as a full replacement to the class diagram. Both the master and
the slave accesses can be customized by a policy. In the case of the master
access, this policy indicates whether the two concurrent operation calls by
the master IP are serialized or have interlaced transactions within the access.
The channel is indeed only capable of managing the concurrency between
master accesses, but remains a concurrency between the threads of the modules
sharing a master access. The slave access policy determines the concurrency
on the operations provided by the slave IP. Several masters can generate
several interleaved transactions to the same slave, especially when the slave
splits the transactions, requiring the slave to have a customizable concurrency
policy.
At last, one may think of composing channels. For example, a slave IP
can be first attached to a FIFO channel which master access could then become