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.\"  * $Source: /vol/opua/opua2/sis/sis-1.1/common/src/sis/sis_lib/help/RCS/stg_extract.1,v $
.\"  * $Author: sis $
.\"  * $Revision: 1.2 $
.\"  * $Date: 1992/05/06 19:04:01 $
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.XX
stg_extract [-a] [-e] [-c]
.PP
Takes the current network and extracts the state transition graph from it.  
.PP
If the \fB-a\fP option is not specified, the values on the latches are taken
to be the start state, and every state reachable from the
start state is explored.  This is the normal method of execution.
.PP
If the \fB-a\fP option is specified, the state transition graph is extracted
for all possible start states, provided the number of latches does not
exceed 16.  This limitation cannot be overridden (there are too many
states to store).
.PP
Extraction of the STG could take an enormous amount of time.
If there are more than 16 latches in the network, \fBstg_extract\fR won't
attempt to extract the STG.
This can be overridden with the \fB-e\fP option.
.PP
At the end of \fBstg_extract\fR, a check is done to ensure that
the behavior of the STG is consistent with that of the logic implementation.
This is done with symbolic simulation using BDDs, and could be expensive.
\fBstg_extract\fR will not do this check for networks with more than
16 latches or more than 500 transitions unless the \fB-c\fR option is given.
.PP
Note: a \fBsweep\fI is done on the network before the STG is extracted.
This removes latches that do not fanout, so the sweep makes the extraction
more efficient.
