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###############################################################################
# Copyright (c) 2013-2024 by Altair Engineering, Inc.
# All rights reserved.
#
# Altair Engineering, Inc. makes this software available as part of the Vision
# tool platform.  As long as you are a licensee of the Vision tool platform
# you may make copies of the software and modify it to be used within the
# Vision tool platform, but you must include all of this notice on any copy.
# Redistribution without written permission to any third party, with or
# without modification, is not permitted.
# Altair Engineering, Inc. does not warrant that this software is error free
# or fit for any purpose.  Altair Engineering, Inc. disclaims any liability for
# all claims, expenses, losses, damages and costs any user may incur as a
# result of using, copying or modifying the software.
# =============================================================================
#   @userware
#       Find Parasitic Nets With No Driver
#   @section
#       Analyze the Loaded Database
#   @description
#       Find parasitic nets with no driver.
#       A driver is either:
#
#       - a top level input port or
#       - an output pin or
#       - a pin with the name `Y`.
#   @files
#       parasitic/undriven.tcl
#   @tag
#       dspf parasitic spf spef
###############################################################################


##
# Create a menu entry to start the code.
#
gui menu command {"Parasitic" "Find Undriven Nets"} {_findUndrivenNets}


# -----------------------------------------------------------------------------
# _findUndrivenNets - Find undriven nets not connected to a pin named 'Y'.
# -----------------------------------------------------------------------------
#
proc _findUndrivenNets {} {
    ##
    # Get the corresponding database.
    #
    set db [gui database get]

    ##
    # Return if the database is empty.
    #
    if {$db == {}} {
        return
    }

    ##
    # Initialize the result list as an empty list.
    #
    set resList {}

    ##
    # Build a list of all nets.
    #
    set netList {}
    $db foreach top top {$db foreach net $top net {lappend netList $net}}

    ##
    # Loop over all nets.
    #
    foreach net $netList {
        ##
        # Set a flag that this net is not driven.
        #
        set isDriven 0

        ##
        # Loop over each pin this net connects to.
        #
        $db foreach pin $net pin {
            ##
            # The default direction of a driver pin is 'output'. If the
            # driver is a top level port then the direction is input.
            #
            set driverDir "output"
            if {[$db oid type $pin] == "port"} {
                set driverDir "input"
            }

            ##
            # If the direction of this pin identify the connection as a
            # driver or the pin name is 'Y' then a driver has been
            # identified - break the loop.
            #
            if {[$db directionOf $pin] == $driverDir || \
                    ([$db oid type  $pin] == "pin"   && \
                     [$db oid pname $pin] == "Y")} {
                set isDriven 1
                break
            }
        }

        ##
        # If this net is not driven then add it to the result list.
        #
        if {!$isDriven} {
            lappend resList $net
        }
    }

    ##
    # Store the result into the Mem Window.
    #
    gui mem clear
    gui mem append $resList

    ##
    # Activate the Mem Window.
    #
    gui window show Mem
}