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  1. #1
    Advanced Member level 5
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    Active HDL vs Models performance


    The company I'm working for is in the process of deciding on a new simulation software.
    We're designing a product around a Medium / Large Xilinx Kintex Ultrascale FPGA.

    Currently we're using Modelsim PE but thinking about
    moving to Active HDL...

    To people that have a lot of experience with both - which one works faster (assuming the same design and logging)?
    Which one is less buggy?
    Are there important features that one has and the other doesn't ?

    •   Alt3rd November 2017, 15:45



  2. #2
    Advanced Member level 5
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    1924 / 1924

    Re: Active HDL vs Models performance

    Since moving to ActiveHDL, Ive found a load of bugs, but these are mostly on some more eosoteric VHDL 2008 stuff. But they were quite serious (simulator not mapping unconstrained record access types to system memory properly - so populating my records with data from adjacent fields/rubbish, and then eventually crashing).
    Currently, active HDL doesnt like having constant records with Null arrays = vsim crash

    This is the kind of stuff I had working in Modelsim previously.

    ActiveHDL really likes you to use their tool as a full development environment - which is very annoying if you're using to driving everything from modelsim's command line. ActiveHDL inisists you have a "workspace" open to function when in the gui. Luckily, you can run it in batchmode and view the waveform without having a workspace open.

    ActiveHDL is stricter to the VHDL LRM than modelsim. I had some code I ported that worked in modelsim ended up failing in ActiveHDL (for correct reasons). They werent even warned in Modelsim, so I suspect it is actually a bug in MS and a SV carry over.

    But at the end of the day, ActiveHDL is much cheaper.

    Both are good at dealing with support requests, but Aldec are pretty quiet - they tend to just pick up the case without any response other than the auto-generated reply. MS would at least give me some sort of "thanks" reply.

    - - - Updated - - -

    As for performace - I cannot say. Without running the same design through both I cant say

    - - - Updated - - -

    And finally - ActiveHDL is a native application. Modelsim GUI runs inside a Tcl.TK gui - hence rather slow and has always been a problem for it. I think the newer versions are moving away from tcl.tk

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