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###############################################################################
# Copyright (c) 2015-2024 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.
# =============================================================================
#   @script
#       Input to MOS Gate Protection
#
#       Algorithm
#           1. Identify all MOS devices in the design.
#           3. Check if the toplevel input port and gate pin is connected via
#              a minimum 200 ohm resistor.
#           4. Add the devices that violate the above rule to the result list.
#
#       Example
#           demo/api/esd/testcase01.sp
###############################################################################


# -----------------------------------------------------------------------------
# check01Pins - inspect connected pins.
# -----------------------------------------------------------------------------
#
proc ESD:check01Pins {db port gatePinsVar resistorPinPairsVar extraPinsVar} {
    upvar 1 $gatePinsVar gatePins
    upvar 1 $resistorPinPairsVar resistorPinPairs
    upvar 1 $extraPinsVar extraPins

    ##
    # Init results
    #
    set gatePins {}
    set resistorPinPairs {}
    set extraPins {}

    ##
    # get connected net
    #
    set net [ESD:connectedNet $db $port]
    if {$net == {}} {
        return
    }

    ##
    # loop over all connected pins
    #
    $db flat foreach pin -addHier $net pin {
        ##
        # Ignore start
        #
        if {[$db oid isequal $pin $port]} {
            continue
        }

        ##
        # store hierPins
        #
        if {[$db oid type $pin] == "port"} {
            lappend extraPins $pin
            continue
        }

        ##
        # Get instance of pin
        #
        set inst [$db oid convertTo inst $pin]

        ##
        # Get primitive type
        #
        set func [$db primFuncOf $inst]

        ##
        # Check different function.
        #
        switch -- $func {
            "NMOS" -
            "PMOS" {
                ##
                # Report direct connected gate pin
                #
                if {[ESD:funcName $db $pin] eq "gate"} {
                    lappend gatePins $pin
                }
            }
            "RES" {
                ##
                # Get opposite resistor pin
                #
                set resistorPin [ESD:oppositePin $db $pin]
                if {$resistorPin != {}} {
                    lappend resistorPinPairs [list $pin $resistorPin]
                }
            }
            default {
                ##
                # all other pins (and hierpins) which might be connected
                #
                lappend extraPins $pin
            }
        }
    }
}


# -----------------------------------------------------------------------------
# check01Port - Check whether port is connected to minimum 200 ohm resistor.
# -----------------------------------------------------------------------------
#
proc ESD:check01Port {db port resultListVar} {
    upvar 1 $resultListVar resultList

    ##
    # Get connected gate pins
    #
    set gatePins {}
    set resistorPinPairs {}
    set extraPins {}
    ESD:check01Pins $db $port gatePins resistorPinPairs extraPins

    ##
    # Gate pins direct connected to port are invalid
    #
    if {[llength $gatePins] > 0} {
        foreach gatePin $gatePins {
            set msg "gate '[$db oid print $gatePin]' without resistor"
            set oids [ESD:filterOids $db $gatePin $port $extraPins]
            ESD:appendResult resultList $port $oids $msg
        }
        return
    }

    ##
    #
    # Check for invalid gates connected via resistor
    #
    foreach resistorPinPair $resistorPinPairs {
        set gatePins {}
        set moreResistorPinPairs {}

        ##
        # get both resistor pins
        #
        set resistorPin1 [lindex $resistorPinPair 0]
        set resistorPin2 [lindex $resistorPinPair 1]

        ##
        # check on other side of resistor
        #
        ESD:check01Pins $db $resistorPin2 gatePins moreResistorPinPairs \
                                          extraPins

        ##
        # Check resistor value for gate pins connected via resistor.
        #
        if {[llength $gatePins] > 0} {
            ##
            # Get instance of pin
            #
            set inst [$db oid convertTo inst $resistorPin1]

            ##
            # Get resistor value
            #
            set resValue [$db attr $inst getValue "R"]

            ##
            # list of oids
            #
            set otherOids [concat $gatePins $resistorPinPair $extraPins]

            ##
            # Gate pins connected via too small resistor is invalid
            #
            if {$resValue < 200} {
                set    msg "resistor '[$db oid print $inst]'"
                append msg " value $resValue too small"
                ESD:appendResult resultList $port $otherOids $msg
                return
            }

            ##
            # Port is ok
            #
            ESD:appendResult resultList $port $otherOids ""
        }
    }
}


# =============================================================================
# Check01 - Input to MOS Gate Protection.
# =============================================================================
#
proc ESD:Check01 {db} {
    ##
    # Initialize the result list.
    #
    set resultList {}

    ##
    # Get top module.
    #
    set top [$db get_top_design]

    ##
    # Count top level ports
    #
    set count 0
    $db foreach port $top port {
        incr count
    }

    ##
    # Loop over all top level ports
    #
    set i 0
    $db foreach port $top port {
        zprogress push "" [expr {double([incr i]) / $count}]

        ESD:check01Port $db $port resultList

        if {[zprogress pop]} {
            break
        }
    }

    ##
    # Return the calculated result.
    #
    return $resultList
}