create_drc_violation - 2023.2 English

Description

Create a DRC violation object and manage the list of design objects associated with the violation for reporting by the report_drc command.

The create_drc_violation command is specified as part of the Tcl checker procedure that defines and implements the checking feature of a user-defined design rule check created by the create_drc_check command. A violation object is created by the Tcl checker each time a violation of the design rule is encountered.

The process in brief is:

• Write a Tcl checker procedure to define the method applied when checking the user-defined rule, and the objects to check against the rule. The Tcl checker procedure is defined in a separate Tcl script that must be loaded by the source command prior to running report_drc.
• Use create_drc_violation in the Tcl checker to identify and flag violations found when checking the rule against a design.
• Define a user-defined DRC rule check using the create_drc_check command that calls the Tcl checker proc from the -rule_body.
• Create a rule deck using the create_drc_ruledeck command, and add the user-defined rule check to the rule deck using the add_drc_checks command.
• Run report_drc, and specify either the rule deck, or the user-defined rule check to check for violations.

Violations are reported by the report_drc command, and violation objects can be returned by the get_drc_violations command. The design objects associated with a DRC violation object can be obtained using the -of_objects option of the appropriate get_* command, such as get_cells, get_nets, or get_ports for instance:

get_ports -of_objects [get_drc_violations -name drc_1 NSTD*]

Arguments

-name <arg> - (Required) The name of the design rule check associated with the violation. This should be the same name used by the create_drc_check command which calls the associated Tcl checker procedure from its -rule_body argument. Messages from the create_drc_violation command are passed up to the drc_check with the same -name.

-severity <arg> - (Optional) The severity of the created violation. This allows individual DRC violations to override the default severity of a specific rule check. The default severity for user-defined DRCs is determined by the definition of -severity in the create_drc_check command. The supported values are:

• ERROR
• "CRITICAL WARNING"
• WARNING
• ADVISORY

-msg <arg> - (Optional) This is a violation specific message that is substituted for the general string variable (%STR) specified in the optional placeholder message defined in the create_drc_check command.

<objects> - (Optional) Cell, port, pin, net, clock region, site, and package I/O bank objects associated with violations found by the Tcl checker procedure that are substituted into the placeholder message of the drc_object with the same -name. Design objects map to substitution keys in the message as follows:

• %ELG - netlist elements such as cells, ports, pins, and nets.
• %CRG - clock regions.
• %SIG - device sites.
• %PBG - package I/O banks.

Examples

The following Tcl script defines the dataWidthCheck procedure which is called by the -rule_body argument of the RAMW-1 check. This Tcl script file must be loaded into the tool using the source command, prior to running the report_drc command.

Some features of the Tcl checker proc to notice are:

• A list variable is created to store violations ($vios )
• A violation object is created, and added to the list variable, each time a violation is found.
• The placeholder key %ELG in the $msg string is dynamically substituted with the specific $bram cell associated with the violation.
• The dataWidthCheck proc returns an error code when any violations are found ($vios >0) to inform the report_drc command of the results of the check.
• The list of violations is passed along with the return code, and the violations are reported by report_drc.

# This is a simplistic check -- report BRAM cells with WRITE_WIDTH_B
# wider than 36.
proc dataWidthCheck {} {
  # list to hold violations
  set vios {}
  # iterate through the objects to be checked
  foreach bram [get_cells -hier -filter {PRIMITIVE_SUBGROUP == bram}] {
    set bwidth [get_property WRITE_WIDTH_B $bram]
    if { $bwidth > 36} {
      # define the message to report when violations are found
      set msg "On cell %ELG, WRITE_WIDTH_B is $bwidth"
      set vio [ create_drc_violation -name {RAMW-1} -msg $msg $bram ]
      lappend vios $vio
    }
  }
  if {[llength $vios] > 0} {
    return -code error $vios
  } else {
    return {}
  }
}
create_drc_check -name {RAMW-1} -hiername {RAMB Checks} \
   -desc {Data Width Check} -rule_body dataWidthCheck \
   -severity Advisory

See Also

• add_drc_checks
• create_drc_ruledeck
• create_drc_check
• get_cells
• get_drc_checks
• get_drc_violations
• get_nets
• get_pins
• get_ports
• get_sites
• report_drc
• set_property