SpecC, HandelC, SystemC : A Comparative Study

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Spec-C, Handel-C, SystemC A Comparative Study

• By Nikola Rank
• 13 March 2006

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What is a Hardware Description Language(HDL)?

• A textual approach to describing electrical
  circuits.
• Not limited to circuit structure, can describe
  temporal/operational behavior.
• Popular examples VHDL, Verilog
• Handel C, SystemC, SpecC are not true HDLs!

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Motivation for Higher Level

• These System-level description languages are
  crucial for SOC design and testing.
• Work at varying levels of abstraction from the
  underlying hardware.
• Simplify hardware/software partitioning by
  describing both with a single, C-based language.
• Enhanced simulation and debugging
• performance.

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Handel C

• Developed by Oxford Hardware Compilation Group
• Based on the language Occam
• Goal Enable someone not familiar with H/W to do
  H/W design
• Currently, Celoxica provides a development suite
  called DK4 that uses Handel C.

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What does Handel add to ANSI-C?

• Parallelism
• Timing
• Interfaces
• Clocks
• RAM/ROM
• Shared expression
• Communications
• Handel-C libraries
• Floating Point component library
• Bit manipulation
• Macro functions for hardware block reuse

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What doesnt Handel C support

• Recursion
• Side effects
• Standard libraries
• Malloc()
• Standard floating point
• Pointers
• Aside from these, everything else in C is
  supported by Handel C

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Handel C design flow

• Sample Handel C design flow (Based on Celoxica
  toolset)
• Goal is implementation of JPEG 2000 algorithm

Image source Celoxica Presentation1
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System C

• Offered by the Open SystemC Initiative (OSCI)
• Implemented via C library, runs on any C
  compiler.
• Includes constructs for testing/simulation as
  well as synthesis.

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System C model
Image source Synthesizable SystemC 2
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Synthesizable Subset

• Only a subset of the SystemC library is suitable
  for synthesis of a circuit.
• This subset closely matches VHDL or another
  underlying HDL.
• In reality, most tools actually convert the
  SystemC to HDL for synthesis.

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System C design flow
Image source Synthesizable SystemC 2
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System C from UML?

• The next level of abstraction above C is UML.
• It may be possible to generate synthesizable
  SystemC code from a UML model.
• Leads to even shorter design times.

Image source Synthesizable SystemC Code from UML
Models3
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Spec C

• First developed in 1997 at University of
  California
• Uses its own special compiler, a reference
  compiler is freely available.
• Designed to be true superset of ANSI-C
• Allows timing specification.

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Spec C model

• Parallelism
• State Transition
• Structural Hierarchy
• Exception Handling
• Timing Constraints
• Synchronization
• Communication
• Data Path

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Spec-C design flow
Image source The SpecC Methodology4
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Conclusions

• There is no doubt a push in the direction of
  higher level languages for hardware design.
• Many more alternatives offered, SystemC, Spec C,
  Handel C, Impulse C, etc
• None are perfect, none are the industry standard
  (Some more prominent than others).
• Future will hold even higher levels of
  abstraction.

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References

• 1 Software-Compiled System DesignA Methodology
  for Field ProgrammableSystem-on-Chip Design.
• EDP paper presentation. Jeff Jussel. April 15,
  2003 (Celoxica)
• 2 Synthesizable SystemC. Federico Angiolini.
  2005-2006 DEIS University of Bologna.
• 3 Synthesizable SystemC Code from UML Models.
  W.H. Tan, P.S. Thiagarajan,W.F. Wong, Y. Zhu.
  School of ComputingNational University of
  Singapore. S.K. Pilakkat. Institute for Infocomm
  ResearchSingapore http//www.comp.nus.edu.sg/ctp/
  publications/UML_SoC.pdf
• 4 The SpecC Methodology. Andreas Gerstlauer.
  Center for Embedded Computer Systems University
  of California, Irvine. 2001. http//www.cecs.uci.e
  du/SpecC/
• 5 Handel-C Language Reference Manual. Embedded
  Solutions Limited Version 2.1
• 6 SpecC Language Reference Manual. SpecC
  Technology Open Consortium Version 2.0. December
  12, 2002
• 7 SystemC 2.0.1 Language Reference Manual. Open
  SystemC Initiative San Jose, California. 2003
• 8 Presentation by SpecC Technology Open
  Consortium http//www.specc.gr.jp/tech/stoc_dac00
  _presen.pdf
• 9 A Survey on the Handel-C Language. Altaf
  Abdul Gaffar. http//www.iis.ee.ic.ac.uk/frank/su
  rp99/article1/amag97