Magic VLSI Layout Tool Version 8.2 *

ext, extract


Circuit netlist extractor

Usage:

extract option

where option may be one of the following:
all
Extract the root cell and all its children. This bypasses the incremental extraction and ensures that a new .ext file is written for every cell definition.
cell name
Extract the currently selected cell into file name
do|no [option]
Enable or disable an extractor option, where option may be one of the following:
capacitance
Extract local parasitic capacitance values to substrate
resistance
Extract lumped resistance values. Note that this is not the same as full parasitic resistance. The values extracted are "lumped" resistance and indicate the value for which the delay through the net can be computed with R times C, where R is the lumped resistance and C is the parasitic capacitance. This is a very coarse approximation, as it assumes equal delay from the driver to any receiver. For full R-C extraction, see the extresist command. Lumped resistances have no meaning in SPICE netlists and will only be used when running ext2sim to generate a .sim netlist.
coupling
Extract the parasitic coupling capacitance between nodes.
length
Extract the length of the shortest path from a driver to a receiver, for computing more accurate parasitic resistances.
adjust
Adjust all capacitances for overlap between a parent cell and child instance, or between instances in an array. Parasitic capacitance is removed to account for the amount of overlap. Note that this method can produce negative capacitors in the parent. When the netlist is flattened for simulation, the total of all capacitances in parent and child, or between array instances, is guaranteed to be strictly positive.
all
Apply all standard options (does not include options "local", "labelcheck", or "aliases").
local
Write all .ext files to the current working directory. If not specified, each .ext file will be placed in the same directory as the .mag file from which it is derived, unless the .mag file is in a directory which is not writable. In that case, the .ext file will also be written to the current working directory.
labelcheck
Check for labels which have zero area and connect to a subcell on the edge; this case is rare but is computationally expensive to check for, so the feature is disabled by default.
aliases
By default (starting with version 8.3.217), magic only extracts a single name for a net, unless the net connects to a port, in which case the port name is extracted as well. With the aliases option enabled, all names for a net are extracted; this can be useful for debugging but will usually just slow down processing by commands like "ext2spice" that use the .ext file contents, so it is disabled by default.
These options (except for "local") determine how much information is written to the output file. By default, all options are selected. Normally, the options in ext2spice or ext2sim are used to select which information from the .ext file is used in the resulting netlist. There is no need to restrict the information being extracted. All options add relatively little overhead to the extraction time. The output file size can be reduced by not generating some extraction information.
length [option]
Control pathlength extraction information, where option may be one of the following:
driver termname
receiver termname
clear
help
Print help information
parents
Extract the selected cell and all its parents
showparents
List the cell and all parents of selected cell. Note that this is not really an extract option and is superceded by the cellname command.
[list|listall] style [stylename]
Set the current extraction style to stylename. Without arguments, print the current extraction style. With keyword list, return the current extraction style as a Tcl result. With keyword listall, return all valid extraction styles for the technology as a Tcl list.
unique [#]
Generate unique names when different nodes have the same name. When option "#" is present, only make unique names for labels tagged by ending with the "#" character.
Warning: This operation immediately modifies the existing layout in preparation for extraction. Label modifications are permanent, and cannot be undone. All cells in the hierarchy may potentially be modified.
unique [option]
(From Magic 8.1.24) With no option, generate unique names when different nodes have the same name. option may be one of the following:
all
Equivalent to no option; all labels with the same name on different nets are given unique names.
#
Labels that are tagged by ending with the character "#" are made unique for each instance on an electrically unique node.
noports
Labels that are not ports are made unique when on different nets. Ports, however, are ignored. This option is useful for standard cells which may be hiding internal connectivity.
notopports
This option behaves like extract unique noports on the topmost cell in the hierarchy, and otherwise behaves like extract unique all on all cells below the top (available from magic 8.3.205).
Warning: This operation immediately modifies the existing layout in preparation for extraction. Label modifications are permanent, and cannot be undone. All cells in the hierarchy may potentially be modified.
warn [[no] option]
Enable/disable reporting of non-fatal errors, where option may be one of the following:
fets
labels
dup
all

Summary:

With no options given, the extract command incrementally extracts the root cell and all its children into separate .ext files. With options, the effect is as described in the Usage section above.

Implementation Notes:

extract is implemented as a built-in magic command.

ext is an alias for command extract (allowed abbreviation where the usage would otherwise be ambiguous).

See Also:

extresist
ext2spice
ext2sim

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Last updated: October 8, 2021 at 4:56pm