Intel® Quartus® Prime Pro Edition User Guide: Scripting

ID 683432
Date 10/04/2021
Public

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3.1.28.7. get_fanouts (::quartus::sdc_ext)

The following table displays information for the get_fanouts Tcl command:

Tcl Package and Version

Belongs to ::quartus::sdc_ext

Syntax get_fanouts [-h | -help] [-long_help] [-asynch] [-clock] [-inverting_paths] [-no_logic] [-non_inverting_paths] [-stop_at_clocks] [-synch] [-through <names> ] <filter>
Arguments -h | -help Short help
-long_help Long help with examples and possible return values
-asynch Traverse through asynchronous edges
-clock Traverse through clock edges
-inverting_paths Only follow inverting combinational paths
-no_logic Do not follow combinational paths
-non_inverting_paths Only follow non-inverting combinational paths
-stop_at_clocks Return clock targets as fanin/fanouts rather than traversing through them
-synch Traverse through synchronous edges
-through <names> Valid through nodes (string patterns are matched using Tcl string matching)
<filter> Valid starting nodes (string patterns are matched using Tcl string matching or collection)
Description

Returns a collection of fanout ports, registers (and optionally clock targets) reachable from the <filter> in the design. When the -no_logic option is used, get_fanouts ignores the paths that pass through combinational logic elements other than buffers and inverters. When you use the -synch, -asynch, or -clock options, get_fanouts traverses the netlist through corresponding edges. You can specify more than one of these options. If you do not specify any of these three options, the command does not ignore any paths. When the -non_inverting_paths option is used in conjunction with the -no_logic option, get_fanouts does not follow paths that include an odd number of inverters. Similarly, when the -inverting_paths option is used in conjunction with the -no_logic option, get_fanouts does not follow any paths that include an even number of inverters. Both the -non_inverting_paths and -inverting_paths options require the -no_logic option and are mutually exclusive. NOTE: The -no_logic option does not consider logic absorbed into the cells of the <filter> nor the cells of fanout registers, ports or clock targets. The -no_inversion option does not consider inversions absorbed into synchronous inputs of fanout registers, as the Intel Quartus Prime software register timing model always considers these edges as being positive unate. When the -through option is used, only the fanouts that can be reached by going through those nodes are returned. When -stop_at_clocks is used, combinational clock targets may be returned (in addition to clock or non-clock registers and ports), and registers or ports that can only be reached by traversing through a clock target will not be returned. The filter for the collection is a Tcl list of wildcards, and must follow standard Tcl or Timing Analyzer-extension substitution rules. See the help for use_timing_analyzer_style_escaping for details.

Example Usage
set fanouts [get_fanouts $item]
foreach_in_collection fanout_keeper $fanouts {
	lappend fanout_keeper_list [get_node_info $fanout_keeper -name]
}

set fanouts_no_logic [get_fanouts $item -no_logic]
foreach_in_collection fanout_keeper $fanouts_no_logic {
	lappend fanout_keeper_list_no_logic [get_node_info $fanout_keeper -name]
}

# Using through option to find the fanout registers whose enable input is 
# connected to the signal while ignoring the inverting paths.
get_fanouts inst1 -no_logic -non_inverting_paths -through [get_pins -hierarchical *|ena]
Return Value Code Name Code String Return
TCL_OK 0 INFO: Operation successful

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