report_carry_chains - 2023.2 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

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2023.2 English

Report carry chains


report_carry_chains [‑file <arg>] [‑append] [‑return_string] [‑cell <args>]
    [‑max_chains <arg>] [‑quiet] [‑verbose]




Name Description
[-file] Filename to output results to. (send output to console if -file is not used)
[-append] Append to existing file
[-return_string] Return report as string
[-cell] Report Carry Chains only for given cell
[-max_chains] Number of chains for which report is to be generated Default: 1
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution




Report the details of the carry chains used by the current open design. The report includes the average depth of all carry chains, as well as the specific depth of each carry chain reported.

By default, the longest carry chain is reported, but the number of chains reported can be specified.

The command returns the carry chain report.


-file <arg> - (Optional) Write the report into the specified file. The specified file will be overwritten if one already exists.

Note: If the path is not specified as part of the file name, the file will be written into the current working directory, or the directory from which the tool was launched.

-append - (Optional) Append the output of the report to the specified file rather than overwriting it.

Note: The -append option can only be used with the -file option.

-return_string - (Optional) Directs the output to a Tcl string rather than to the standard output. The Tcl string can be captured by a variable definition and parsed or otherwise processed.

Note: This argument cannot be used with the -file option.

-cell <arg> - (Optional) Specify a cell to use when analyzing carry chains. When specified, analysis is limited to only the hierarchical cell specified and to any sub-modules of that cell.

-max_chains <arg> - (Optional) Number of chains to report. By default the longest carry chain is reported.

-quiet - (Optional) Execute the command quietly, returning no messages from the command. The command also returns TCL_OK regardless of any errors encountered during execution.
Note: Any errors encountered on the command-line, while launching the command, will be returned. Only errors occurring inside the command will be trapped.
-verbose - (Optional) Temporarily override any message limits and return all messages from this command.
Note: Message limits can be defined with the set_msg_config command.


The following example returns the 10 longest carry chains in the design:

report_carry_chains -max_chains 10