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maehne

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maehne last won the day on November 1

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About maehne

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  1. maehne

    tlm_socket_base_if

    Thanks for the clarification and feedback on the fix suggested by Philipp!
  2. maehne

    tlm_socket_base_if

    Dear Guillaume, thanks for reporting this issue! I have forwarded your report to the Language Working Group for further analysis. From a first look, this is indeed a change in behaviour of the SystemC proof-of-concept implementation from version 2.3.1 to 2.3.2. However, it does not seem to touch the standard IEEE Std 1666-2011, as the latter does not mention member function `get_protocol_types()`. Regards, Torsten
  3. maehne

    Direct Digital Synthesis

    As you can see from the DDS block diagram, which you posted, the structure of DDS block is quite simple. I therefore would model it as a single TDF module containing the accumulator register as a state variable. As input, you will have your frequency control and phase offset control signals. The frequency control signal basically is the value, which you continuously add to the value in your accumulator register to generate a periodic sawtooth signal (due to the overflow of the accumulator). The phase offset control signal gets added to the accumulator register to enable shifting the phase of the sawtooth signal. This sawtooth signal is interpreted as the angle operand of a sine function. The period of the sawtooth signal represents a full revolution on the phase circle, i.e., the 2^L possible sawtooth signal values are evenly mapped to phase angles in the range of 0 rad to 2 pi rad (0° to 360°). To avoid repeated calculations of the sine function, the sine amplitudes for all possible angles are pre-calculated and stored in a look-up table (LUT). The current value of the sawtooth signal is then used as the index into that look-up table to find the corresponding output amplitude. To implement this in a generic DDS TDF module, I would choose M, L, and K (bit widths) as generic parameters, which can be passed upon DDS module instantiation to the DDS module's constructor. From M and L, you can calculate the value for the modulo operation, which models in software your overflowing of a M-bits-wide and L-bits-wide addition operation. The difference of M and L gives you the shift distance needed to implement your accumulator output quantisation. The sine LUT needs to have 2^L entries. The sine function should be scaled by 2^(k-1)-1 to use the full range of a k bit wide signed output. All these preparatory calculations, you can do in your DDS module's constructor. The processing function then only needs to only implement the two additions and the amplitude look-up based on the current values of the frequency and phase control inputs and the current value stored in the accumulator register. If you plan to use this kind of module in a model of communication system, you might consider having a look to the Vienna SystemC AMS Building Block Library, which is available for download from systems-ams.org. The latter web site contains also other useful SystemC AMS resources.
  4. maehne

    ELN Low pass filter

    Well, you will have to write a test bench, which provides your RC filter with some stimuli for transient simulation or sets up an AC analysis. However, I recommend you to have first a closer look to the fundamental concepts and ideas of SystemC AMS. A good introduction to SystemC AMS is provided by the SystemC AMS extensions User's Guide, which is part of the SystemC AMS extensions 1.0 release. Even though, this discusses only the features available sind SystemC AMS 1.0, it is a good start as SystemC AMS 2.0 and IEEE Std 1666.1 added mainly advanced features related to Dynamic TDF and bug fixes. Also, the SystemC AMS community pages provide some good links to introductory resources to get started with SystemC AMS.
  5. maehne

    tlm_fifo nb_peek

    Thanks for providing this feedback on the SystemC PoC implementation! It would help if you could share some more details about the exact error messages as well as a minimal self-contained example exposing the problem you are observing. Then, we may discuss the issue more seriously.
  6. Thanks for reporting this Aarm64-specific issue! I have forwarded it to the Language Working Group's bug tracker so that we can have a look. Support for Aarm64 in SystemC is relatively new. To help localise the source of the problem, could you try whether it helps to configure SystemC to use Pthreads instead of QuickThreads in addition to `--enable-debug --disable-optimize`?
  7. maehne

    SystemVerilog "program" scope

    It is up to the IEEE P1666 working group to decide, which currently experimental SystemC API features become official part of a future IEEE Std 1666 revision. The companies/people involved in the maintenance of the SystemC PoC simulator are also actively involved in this standardisation effort. The implementation of experimental features into the PoC implementation serve as a testbed to gain experience with them and collect feedback on their functionality, usability, and usefulness and real world applications. That is important input for the standardisation process.
  8. maehne

    A SystemC installl problem on Ubuntu

    If it is necessary for you to stick with SystemC 2.3.1, you can simply comment out the offending line in systemc.h. The function is nowhere used inside the proof-of-concept implementation of SystemC.
  9. Yes, this change in behaviour of SystemC 2.3.2 with respect to SystemC 2.3.1 is intentional to better conform to IEEE Std 1666-2011, which states in clause 6.4.4 about signal writes under the SC_MANY_WRITERS policy: This fix by @Philipp A Hartmann is documented in the RELEASENOTES of SystemC 2.3.2:
  10. maehne

    make check return fail

    @David Black: Did you yet find the time to attempt to fix the sem_init issue on macOS?
  11. maehne

    Static Analyzer Report of SystemC-2.3.2

    Thanks Sumit for reporting these issues! I have reported them to the Language Working Group so that we can try to fix them in the proof-of-concept implementation. Regards, Torsten
  12. maehne

    How SystemC kernel is implemented !!

    Regarding sc_simcontext, this class is not part of IEEE Std 1666-2011! It is an implementation artefact, which should not concern you as a user. The proof-of-concept implementation uses it for house-keeping and managing the global state of the simulation kernel.
  13. maehne

    How SystemC kernel is implemented !!

    If you are interested in the elaboration and simulation semantics of SystemC, have a look to clause 4 of IEEE Std 1666-2011. The simulation semantics are based on the discrete-event model of computation and employ the concept of delta cycles to achieve determinism of the simulation results. This is very close to other hardware description languages such as VHDL. Using your favourite search engine, you can find additional information such as the following two tutorials: John Moondanos "SystemC Tutorial" Federico Angiolini "SystemC Tutorial" which give a brief summary of these semantics and the core ideas of SystemC. Though, please take into account that both tutorials are 10+ years old, which means that certain aspects have evolved considerably. For a good introduction to SystemC, I suggest that you read a good book on the topic, such as "SystemC from the Ground Up" by David Black et al. To efficiently use SystemC, you have to master the core concepts of C++ first.
  14. maehne

    A SystemC installl problem on Ubuntu

    This issue has been fixed in the SystemC 2.3.2 release available from the Accellera website. The function std::gets was definitely removed in the C'11 standard and deprecated in the C++'11 standard so that recent compilers do not provide it anymore as its semantics constitutes a security risk due to buffer overflows.
  15. I am afraid, this is a question, which only @David Black or one of his co-authors of the book can answer. As far as I can remember, I could never find the advertised online material under the URL mentioned in the book. Nevertheless, I still consider it one of the best books on the topic of SystemC.
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