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lvx.1alc - Man Page

Logical Versus eXtracted net-list comparator


lvx format1 format2 filename1 filename2 [ -a ] [ -u ] [ -o ] [ -f ]


lvx compares two gate-level or block level net-list. The goal is to compare a specification net-list (logical net-list), the input to a place and route tool, with the physical net-list (extracted net-list) obtained by the cougar(1) extractor.
The net-list 1 is considered as the logical net-list and net-list 2 as the extracted net-list.

lvx is an one-level hierarchical tool:

The two net-list are flattened, if the -f option is present, to the cells contained in the catalog file. The path to the catalog file is indicated in the MBK_CATA_LIB(1) variable for the cell library, and in the MBK_WORK_LIB(1) variable with the name MBK_CATAL_NAME(1) for user blocks ( catal(5) ) that are not to be flattened.

For both net-list, the instances are considered as black-boxes.

The two net-list must have the same external connectors names.

The two net-list must have the same instances names.

The two net-list must have the same signals names for unconnected signals.

The two net-list cannot directly contain transistors.

Comparison is performed in three steps:

Compare terminals.

Compare instances.

Compare connections.

Compare unconnected signals.

If an error occurs during first or second step, a message is immediately displayed and the third step will not start: lvx cannot compare connections (signals) if terminals or instances are not equivalent.
The -o option allows to order connectors if the steps described before have been reached successfully. Extracted_netlist is then saved on disk. The file get the name filename2 suffixed by the value of MBK_OUT_LO(1) variable.
Routers add automatically empty feed-through cells. These cells must not be taken into account in the comparison. A cell that have the F attribute in the catalog file ( catal (5) ) is considered as feed-through cell, and are deleted, in memory, from the net-list where it appears.



Some routers generate layout with several physical connectors for power and ground ( VDD or VSS ). If those connectors are not internally connected, they will have different indexed names ( VDD1 , VDD2 etc...) in the extracted net-list. It is possible to perform reduction on those power and ground connectors before comparison, using the -a option. After reduction, each instance contains only one VDD connector and one VSS connector, as the main figure.


In this case, lvx produces a modified net-list (saved with the name filename2 ), which is a copy of net-list 2 with ordered connectors. Terminals and instance connectors are relisted in the order of the models in net-list 1. The saved net-list is done with the MBK_OUT_LO(1) format, so user has to set this variable before running lvx . If he does not, default value is used, and net-list 1 could be lost if filename are identical and input format same as output format.
If -a option is used, then the saved net-list is the reduced net-list with only one VDD and one VSS .


This option force lvx to check the consistency of unassigned signals between the two netlists.


The two net-lists are flattened to the leaf cells contained in the catalog file. Usually the extracted net-list is a flatten net-list, while the logical one can be a hierarchical net-list.


With logical_netlist named amd2901.vst and the corresponding extracted_netlist as amd2901.al containing multiple power connectors, the command line is :

lvx vst al amd2901 amd2901 -a

Output Files


Netlist view saved when the -o option is present. The suffixe depend on the MBK_OUT_LO(1) environment variable.

Environment Variables


contains the directories where the cell librtaries are. MBK_WORK_LIB contains the directory path of the working directory, usually set to . (dot).


contains the expected format of the netlist output.


contains the name of the user cell catalog.

See Also

cougar(1), MBK_OUT_LO(1), MBK_WORK_LIB(1), MBK_CATA_LIB(1), MBK_CATAL_NAME(1), catal(5) .


The string "_logic" is appended to the net-list 1 and the string "_extract", is appended to the net-list 2.

Two kinds of error message can occur:

A fatal error causes the program to exit. It happens when one of the net-lists is not correct, lvx cannot construct internal structure for compare.

A compare error occurs when the figures are not identical. It happens when basic objects (instances, connectors) do not exist in both net-list, or when connections (signals) do not connect same terminals or instances in the two net-lists.

Exit code 0 is returned for identical net-lists.

Referenced By