Integrated Modeling Using Finite State Machines and Dataflow Graphs - Signal Processing Systems - page 983

CAL2C synthesis flow

*.cpp
*.hpp

trans−
formations

code
generation

*.cpp
*.hpp

CAL source

parser

CAL AST C * p

*.hpp

actor
parameter

code
generation

NL network
description

NL AST NL AST *.hpp

parser

elaboration

Fig. 19 Design flow using of the CAL2C utility compiling CAL into C ++ code

level of the clustered graphs is associated with a certain MoC. For the analysis of
such a hierarchy level, the classical approaches known for the corresponding MoC
are employed.
However, the decomposition of an application into hierarchy levels with explicit
MoC assignments can be problematic for the designer. Therefore, a tendency to
select the most general MoC, e.g., process networks instead of synchronous dataflow
for the hierarchy levels can be observed. Furthermore, Ptolemy II only allows
simulation and target code generation. Also, there is currently no support for mixed
hardware/software implementations.
In the following, we will discuss OpenDF , a design framework based on CAL ,
and SystemCoDesigner , a design methodology based on S YSTE M O C. Both of these
frameworks support the synthesis of integrated FSM and dataflow models into
hardware/software implementations.

4.2 The OpenDF Design Flow

The OpenDF project [ 4 ] provides design entry, simulation, and debugging support
for the CAL language [ 11 ] . Dataflow graphs are specified via network language ( NL )
which instantiates the CAL actors. The actor parameters derived from the instantia-
tion of the actors in the NL file are inserted and the CAL source code is parsed and
transformed into an XML intermediate representation. This representation is used for
various transformations, e.g., type inference, type checking, constant propagation,
and dataflow analysis. The result is an intermediate representation of the CAL source
code in static single assignment form ( SSA ). From this result, either a simulation can
be executed or two different synthesis backends generating C

++ or verilog source

code can be started . 8
The software synthesis tool CAL2C [ 24 ] supports two synthesis targets one
targeting POSIX threads and software FIFOs , the other one targeting the SystemC
environment, using it as a process network ( PN ) simulation framework. The
synthesis process, also depicted in Fig. 19 , is done by (i) translating the NL dataflow

8 The CAL simulator component of the OpenDF environment can be downloaded from sourceforge
[ 23 ] .