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schematic vs schematic (SVS) not (LVS)

hycmoshycmos
in General

in manual, about LVS:

compare
This method (compare will extract the netlist (if not already done) and compare it against the schematic. 
It returns true on success and false otherwise, in case you like to take specific actions on success or failure.

It seems the command "compare" is used to compare(layout, old.cir)
sometimes, after I modified my schematic, I want to compare the new schematic (new.cir) to an old schematic (old.cir).
So can the command "compare" compare two netlists rather than layout-vs-schematic?
for example,
compare(new.cir, old.cir)

Thanks
Hycmos

Comments

  • MatthiasMatthias
    edited February 2020

    Hi,

    yes, that's possible. But not within the framework of LVS.

    LVS is just a wrapper around the scripting API, so you can basically code a script which does this.
    The problem is that there is no infrastructure for this application yet: no file format, no browser etc.
    The LVSDB format keeps a lot of information for layout back-annotation and probing which is
    not available in your case.

    A solution is either to tweak the LVS infrastructure (which can't be done without code changes
    at the core) or to rebuild a simple infrastructure for your purpose. The key element is the
    "NetlistCompareLogger" which is essentially a listener receiving events (success, mismatch)
    while the netlist compare happens.

    Here is a simple implementation taken from the unit tests. It will just print results as compare
    proceeds. You can basically tailor the output to your needs:

    # This class provides a receiver for netlist compare events
class NetlistCompareTestLogger < RBA::GenericNetlistCompareLogger

  def initialize
    @texts = []
  end

  def out(text)
    @texts << text
  end

  def device_class_mismatch(a, b)
    out("device_class_mismatch " + dc2str(a) + " " + dc2str(b))
  end

  def begin_circuit(a, b)
    out("begin_circuit " + circuit2str(a) + " " + circuit2str(b))
  end

  def end_circuit(a, b, matching)
    out("end_circuit " + circuit2str(a) + " " + circuit2str(b) + " " + (matching ? "MATCH" : "NOMATCH"))
  end

  def circuit_skipped(a, b)
    out("circuit_skipped " + circuit2str(a) + " " + circuit2str(b))
  end

  def circuit_mismatch(a, b)
    out("circuit_mismatch " + circuit2str(a) + " " + circuit2str(b))
  end

  def match_nets(a, b)
    out("match_nets " + net2str(a) + " " + net2str(b))
  end

  def match_ambiguous_nets(a, b)
    out("match_ambiguous_nets " + net2str(a) + " " + net2str(b))
  end

  def net_mismatch(a, b)
    out("net_mismatch " + net2str(a) + " " + net2str(b))
  end

  def match_devices(a, b)
    out("match_devices " + device2str(a) + " " + device2str(b))
  end

  def device_mismatch(a, b)
    out("device_mismatch " + device2str(a) + " " + device2str(b))
  end

  def match_devices_with_different_parameters(a, b)
    out("match_devices_with_different_parameters " + device2str(a) + " " + device2str(b))
  end

  def match_devices_with_different_device_classes(a, b)
    out("match_devices_with_different_device_classes " + device2str(a) + " " + device2str(b))
  end

  def match_pins(a, b)
    out("match_pins " + pin2str(a) + " " + pin2str(b))
  end

  def pin_mismatch(a, b)
    out("pin_mismatch " + pin2str(a) + " " + pin2str(b))
  end

  def match_subcircuits(a, b)
    out("match_subcircuits " + subcircuit2str(a) + " " + subcircuit2str(b))
  end

  def subcircuit_mismatch(a, b)
    out("subcircuit_mismatch " + subcircuit2str(a) + " " + subcircuit2str(b))
  end

  def text
    return @texts.join("\n") + "\n"
  end

  def clear
    @texts = []
  end

  def dc2str(x) 
    return x ? x.name : "(null)"
  end

  def circuit2str(x) 
    return x ? x.name : "(null)"
  end

  def device2str(x) 
    return x ? x.expanded_name : "(null)"
  end

  def net2str(x) 
    return x ? x.expanded_name : "(null)"
  end

  def pin2str(x) 
    return x ? x.expanded_name : "(null)"
  end

  def subcircuit2str(x) 
    return x ? x.expanded_name : "(null)"
  end

end


# This is the actual compare step

cir_path1 = ... # path to first Spice file
cir_path2 = ... # path to second Spice file

nl1 = RBA::Netlist::new
nl1.read(cir_path1, RBA::NetlistSpiceReader::new)

nl2 = RBA::Netlist::new
nl2.read(cir_path2, RBA::NetlistSpiceReader::new)

logger = NetlistCompareTestLogger::new
comp = RBA::NetlistComparer::new(logger)
# dump compare log
puts comp.text

    Regards,

    Matthias

  • hycmoshycmos

    Sir,
    Thank you very much for your patience.
    I plan to study the code to understand the method.
    hope I can implement this work. <3

  • MatthiasMatthias

    Good luck :)

    Please note I have added "puts comp.text" to dump the collected compare report.

    Matthias

  • hycmoshycmos

    get a script error:
    undefined method `text' for #-RBA::NetlistComparer:0x0000000030d94c18-

    can not run the line "puts comp.text".
    But I can see you defined the function text in class NetlistCompareTestLogger < RBA::GenericNetlistCompareLogger.

  • MatthiasMatthias
    edited March 2020

    Sorry, please replace the actual compare code by this:

    # This is the actual compare step

cir_path1 = ... # path to first Spice file
cir_path2 = ... # path to second Spice file

nl1 = RBA::Netlist::new
nl1.read(cir_path1, RBA::NetlistSpiceReader::new)

nl2 = RBA::Netlist::new
nl2.read(cir_path2, RBA::NetlistSpiceReader::new)

logger = NetlistCompareTestLogger::new
comp = RBA::NetlistComparer::new(logger)
comp.compare(nl1, nl2)
# dump compare log
puts logger.text

    (I cannot edit the code above as the editing period expired).

    The code is just a sketch ... there is a lot more to say about tweaking the compare step. Please study the methods provided by Netlist and NetlistComparer for various options that can be used for this purpose. SVS is a new application. Please don't expect it to work out of the box.

    Matthias

  • daidai

    Hi @Matthias
    Do you have any way to ignore or set tolerance for parameter for SVS check?. two my netlists has a different width of device so it flag connection mismatch also. It should be show property mismatch only.

    Thank you,
    dai

  • MatthiasMatthias

    Yes, that is basically possible. You can attach some criterion to a DeviceClass which tell the comparer whether devices are considered equal or not. If you skip a parameter in that definition it is not compared.

    See here for details and a code sample: https://www.klayout.de/doc-qt5/code/class_EqualDeviceParameters.html

    netlist is the first input netlist as I recall.

    Please note that such features may be subject to change. I focus on keeping LVS script stable, not the implementation details.

    Matthias

  • dick_freebirddick_freebird

    There is a "netgen" which performs any-to-any netlist compare.
    Not easy to find although it's part of the efabless / opencircuitdesign
    MAGIC-based toolchain (there are other "netgen" developments,
    newer and unrelated, which Bogart the search engine results). As
    I make it out, the results can be cryptic and not necessarily easy to
    get a graphical display, of. But people make it work on LSI / VLSI
    layouts from schematic and it seems netlist-source-agnostic.

    http://opencircuitdesign.com/netgen/

  • daidai

    Thank @Matthias.
    Thank @dick_freebird.

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