SystemC from scratch. Part 3 « New Horizons - FPGA design - SystemC - Wild Skating - Mac

Jun 20, 2008

SystemC from scratch. Part 3

Our first example

The best way to learn a new tool or language is to look at some examples already available. The SystemC installation includes a number of examples. Let's take a look at one of them. Here is the example directory.

The FIR filter

We will start with the FIR example. But before we do let's find out a little bit more about FIR filter design. Here is a good place to start: http://www.dspguru.com/info/faqs/firfaq.htm

FIR (Finite Impulse Response) filters are one of two primary types of digital filters used in Digital Signal Processing (DSP) applications (the other type being IIR). Compared to IIR filters, FIR filters offer the following advantages:

They can easily be designed to be "linear phase" (and usually are). Put simply, linear-phase filters delay the input signal, but don't distort its phase.
They are simple to implement. On most DSP microprocessors, the FIR calculation can be done by looping a single instruction.
They are suited to multi-rate applications. By multi-rate, we mean either "decimation" (reducing the sampling rate), "interpolation" (increasing the sampling rate), or both. Whether decimating or interpolating, the use of FIR filters allows some of the calculations to be omitted, thus providing an important computational efficiency. In contrast, if IIR filters are used, each output must be individually calculated, even if it that output will discarded (so the feedback will be incorporated into the filter).
They have desireable numeric properties. In practice, all DSP filters must be implemented using "finite-precision" arithmetic, that is, a limited number of bits. The use of finite-precision arithmetic in IIR filters can cause significant problems due to the use of feedback, but FIR filters have no feedback, so they can usually be implemented using fewer bits, and the designer has fewer practical problems to solve related to non-ideal arithmetic.
They can be implemented using fractional arithmetic. Unlike IIR filters, it is always possible to implement a FIR filter using coefficients with magnitude of less than 1.0. (The overall gain of the FIR filter can be adjusted at its output, if desired.) This is an important considertaion when using fixed-point DSP's, because it makes the implementation much simpler.

SystemC FIR example

The SystemC example implements the following program structure:

Running a SystemC simulation

We will start by running a complete SystemC simulation to verify that everything is working. First we goto to the FIR simulation directory:
-> cd /home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/objdir/examples/sysc/fir
We will start by removing all object files: -> rm *.o

Now we can use the makefile that comes with the installation to compile and run the FIR simulation: -> make check
Here is the result:

==> make check
make fir fir_rtl
make[1]: Entering directory `/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/objdir/examples/sysc/fir'
g++ -DPACKAGE_NAME="" -DPACKAGE_TARNAME="" -DPACKAGE_VERSION="" -DPACKAGE_STRING="" -DPACKAGE_BUGREPORT="" -I. -I../../../../examples/sysc/fir -I/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/include    -Wall -DSC_INCLUDE_FX -O3 -c -o stimulus.o `test -f 'stimulus.cpp' || echo '../../../../examples/sysc/fir/'`stimulus.cpp
g++ -DPACKAGE_NAME="" -DPACKAGE_TARNAME="" -DPACKAGE_VERSION="" -DPACKAGE_STRING="" -DPACKAGE_BUGREPORT="" -I. -I../../../../examples/sysc/fir -I/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/include    -Wall -DSC_INCLUDE_FX -O3 -c -o display.o `test -f 'display.cpp' || echo '../../../../examples/sysc/fir/'`display.cpp
g++ -DPACKAGE_NAME="" -DPACKAGE_TARNAME="" -DPACKAGE_VERSION="" -DPACKAGE_STRING="" -DPACKAGE_BUGREPORT="" -I. -I../../../../examples/sysc/fir -I/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/include    -Wall -DSC_INCLUDE_FX -O3 -c -o fir.o `test -f 'fir.cpp' || echo '../../../../examples/sysc/fir/'`fir.cpp
g++ -DPACKAGE_NAME="" -DPACKAGE_TARNAME="" -DPACKAGE_VERSION="" -DPACKAGE_STRING="" -DPACKAGE_BUGREPORT="" -I. -I../../../../examples/sysc/fir -I/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/include    -Wall -DSC_INCLUDE_FX -O3 -c -o main.o `test -f 'main.cpp' || echo '../../../../examples/sysc/fir/'`main.cpp
g++ -Wall -DSC_INCLUDE_FX -O3   -o fir stimulus.o display.o fir.o main.o -L/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/lib-linux -lsystemc -lm
g++ -DPACKAGE_NAME="" -DPACKAGE_TARNAME="" -DPACKAGE_VERSION="" -DPACKAGE_STRING="" -DPACKAGE_BUGREPORT="" -I. -I../../../../examples/sysc/fir -I/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/include    -Wall -DSC_INCLUDE_FX -O3 -c -o fir_fsm.o `test -f 'fir_fsm.cpp' || echo '../../../../examples/sysc/fir/'`fir_fsm.cpp
g++ -DPACKAGE_NAME="" -DPACKAGE_TARNAME="" -DPACKAGE_VERSION="" -DPACKAGE_STRING="" -DPACKAGE_BUGREPORT="" -I. -I../../../../examples/sysc/fir -I/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/include    -Wall -DSC_INCLUDE_FX -O3 -c -o fir_data.o `test -f 'fir_data.cpp' || echo '../../../../examples/sysc/fir/'`fir_data.cpp
g++ -DPACKAGE_NAME="" -DPACKAGE_TARNAME="" -DPACKAGE_VERSION="" -DPACKAGE_STRING="" -DPACKAGE_BUGREPORT="" -I. -I../../../../examples/sysc/fir -I/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/include    -Wall -DSC_INCLUDE_FX -O3 -c -o main_rtl.o `test -f 'main_rtl.cpp' || echo '../../../../examples/sysc/fir/'`main_rtl.cpp
g++ -Wall -DSC_INCLUDE_FX -O3   -o fir_rtl stimulus.o display.o fir_fsm.o fir_data.o main_rtl.o -L/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/lib-linux -lsystemc -lm
make[1]: Leaving directory `/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/objdir/examples/sysc/fir'
make check-TESTS
make[1]: Entering directory `/home/svenand/root/projects/SystemC/libraries/systemc-2.2.0/objdir/examples/sysc/fir'

             SystemC 2.2.0 --- Jun 8 2008 12:54:47
        Copyright (c) 1996-2006 by all Contributors
                    ALL RIGHTS RESERVED
Stimuli : 0 at time 9000
Display : 0 at time 10000
Stimuli : 1 at time 19000
Display : -6 at time 20000
Stimuli : 2 at time 29000
Display : -16 at time 30000
Stimuli : 3 at time 39000
Display : -13 at time 40000
Stimuli : 4 at time 49000
Display : 6 at time 50000
Stimuli : 5 at time 59000
Display : 7 at time 60000
Stimuli : 6 at time 69000
Display : -33 at time 70000
Stimuli : 7 at time 79000
Display : -50 at time 80000
Stimuli : 8 at time 89000
Display : 87 at time 90000
Stimuli : 9 at time 99000
Display : 446 at time 100000
Stimuli : 10 at time 109000
Display : 959 at time 110000
Stimuli : 11 at time 119000
Display : 1495 at time 120000
Stimuli : 12 at time 129000
Display : 1990 at time 130000
Stimuli : 13 at time 139000
Display : 2467 at time 140000
Stimuli : 14 at time 149000
Display : 2960 at time 150000
Stimuli : 15 at time 159000
Display : 3466 at time 160000
Stimuli : 16 at time 169000
Display : 3968 at time 170000
Stimuli : 17 at time 179000
Display : 4470 at time 180000
Stimuli : 18 at time 189000
Display : 4972 at time 190000
Stimuli : 19 at time 199000
Display : 5474 at time 200000
Stimuli : 20 at time 209000
Display : 5976 at time 210000
Stimuli : 21 at time 219000
Display : 6478 at time 220000
Stimuli : 22 at time 229000
Display : 6980 at time 230000
Stimuli : 23 at time 239000
Display : 7482 at time 240000
Simulation of 24 items finished at time 240000
SystemC: simulation stopped by user.
PASS: fir

Congratulations! We have run our first SystemC simulation.

Posted at 11:21 am by svenand


	robin_ny July 16, 2009 06:38 AM PDT Hello. First thank you for your efforts. I am learning SystemC and I ran into a trouble trying to installing SCV (SystemC verification) library in Ubuntu 8.04. I followed the INSTALL guides. The SystemC is already installed in the /usr/local/systemc-2.2 directory. I was attemting to install SVC in the /usr/local/svc folder. The ../configure with the prefix and other stuff worked fine. But when I tried "make" it, it gave me two errors. I have used g++ version 4.2.4 for SystemC. I am not sure if this is related to gcc or it is a script issue with sh -h. I run ubuntu is in Sun's virtualbox as well as on a stand alone desktop. (not that it makes any difference). Any help would be appreciated.


	svenand June 24, 2008 07:25 AM PDT I have not planned any SystemC to RTL synthesis. My idea about using SystemC is to build a virtual platform where I can simulate my design using TLM methods. Any inputs on how to do SystemC to RTL synthesis are welcomed. Sven


	robin June 22, 2008 10:30 PM PDT Just was wondering what is your planned approach to RTL synthesis from SystemC. I am on similar track to learn SystemC, but have a limited budget and so I have been trying to find open-source tools. So far the only one I have found is sv2v, a translator from SystemC to Verilog. Unfortunately, this tool does not appear to handle all of SystemC's (V2.2.0) syntax and semantics. I have looked in SystemCrafter, but only allows for a 2 (?!) day trial period, then it's 3K USD. Anyway, I would be interested in your thoughts on this.

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