1. OCAPI versus SYSTEMC a case study comparing two class libraries for object oriented hardware design
Made by
Benny Thörnberg
Mid Sweden University

2. Copyright Benny Thörnberg 2001
Task description
Comparison of modeling a multimedia system in both Ocapi and SystemC.
Investigate how good the memory part of the multimedia system is modeled
by these two object oriented approaches.
Comparison of simulation performance in both Ocapi and SystemC.
How is hardware synthesis handled for Ocapi and SystemC?
Suggest improvements to the memory handling.
Copyright Benny Thörnberg 2001

3. Copyright Benny Thörnberg 2001
Method
Creating test stimuli to be used for functional verification and comparison
of simulation performance.
Defining a suitable video file format.
Design of viewing and creation tools to support it.
Model the selected filter in Ocapi.
Model the filter in SystemC.
Compare modeling capabilities and simulation performance.
Copyright Benny Thörnberg 2001

4. Selected filter algorithm
Scene change indication
Median filter
MUX
Output
Pixel
Thresholds
Copyright Benny Thörnberg

5. High-level model of the video filter
Algorithm
DO DI col row frnum
Frame memory
Output video stream
Input video stream
fsync
PARAMETER
TIME AT INITIALIZATION
No of rows
Run time
No of columns
No of frames
Compile time
Chrominance threshold
Luminance threshold
Copyright Benny Thörnberg 2001

6. RTL-model of the video filter
Controller
DO DI col row frnum
Frame memory
Output video stream
Input video stream
Frame sync DO DI
pix
slice rd wr T U B E
Internal memory
DO DI col row frnum
Row sync
Copyright Benny Thörnberg 2001

7. Copyright Benny Thörnberg 2001
Simulation result
Stimuli
199 x 119
sized frames
5% salt&pepper noise
PSNR = 18.8 dB
Luminance threshold:
Chrominance threshold:
PSNR [dB]
Filter output
Copyright Benny Thörnberg 2001

8. Copyright Benny Thörnberg 2001
Results
Parameter
Ocapi
SystemC
Simulation scheduler
Linear programming
Real time kernel
Models needed for simulation
Design, test bench and parts of the simulator
Design and test bench
Resolved signals for memory interface
No (implicit)
Yes
Supports hierarchical design No
Explicit support for memory hierarchies
Memory usage for 576 x 705 sized frames (PAL)
325 Mb
43 Mb
Simulation performance, RTL-model
120x200 frame
95 [sec./frame]
515 [sec./frame]
Hardware synthesis
Transformations and external tool
Compiler
Lines of code
4160
2670
Copyright Benny Thörnberg 2001

9. Copyright Benny Thörnberg 2001
Conclusions
This thesis shows that SystemC is more suitable than Ocapi for modeling video
systems, based on several facts:
It is easier to conceptualize memory hierarchy and IP-reuse in SystemC.
There is a huge difference in memory usage that significantly points out
SystemC to be the winner.
Simulation is faster in Ocapi for our test setup. Changing SystemC
modeling style from threads to methods will reduce the difference.
The SystemC initiative is based on cooperation between the worlds
leading EDA-companies and should have a fair chance of becoming
a standardized specification language.
Copyright Benny Thörnberg 2001

10. Copyright Benny Thörnberg 2001
Future work
Copyright Benny Thörnberg 2001