.\" /*
.\"  * Revision Control Information
.\"  *
.\"  * $Source: /vol/opua/opua2/sis/sis-1.1/common/src/sis/sis_lib/help/RCS/speed_up.1,v $
.\"  * $Author: sis $
.\"  * $Revision: 1.2 $
.\"  * $Date: 1992/05/06 19:04:01 $
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.XX
speed_up [-m model] [-d #] [-w #] [-t #.#] [-i] [-c] [-T] [-a #] [-vD] node-list
.PP
Speed-up the nodes in the \fBnode-list\fR. If no nodes are
specified, it selects the nodes to be speeded-up in order to
speed-up the entire network. The best decomposition seen
so far is accepted (except with the \fB-c\fR flag).  The network
after running speed_up is composed of 2-input AND gates and inverters.
.PP
The \fB-m model\fR option selects the delay model according to
which the delay data is computed. The values allowed for
\fBmodel\fR are \fIunit\fR, \fIunit-fanout\fR and \fImapped\fR.
The \fIunit\fR
delay model counts the level of the circuit as its delay.
The \fIunit-fanout\fR model is intended to capture
a technology-independent model and it assigns a delay of 1 unit to each
gate and 0.2 units to each fanout stem. The \fImapped\fR delay
model uses the delay data in the library to compute delay.
.PP
The \fB-d #\fR option selects the distance up to which the 
critical fanins are collapsed in order to do the speed-up.
A fast value is 3, a good one is 6.
.PP
The \fB-t #.#\fR option determines which nodes are considered 
critical. The critical nodes are those with a slack within
#.# of the most negative slack.
.PP
The \fB-w #\fR option selects between the area mode and the 
pure timing mode.  A value of 0 selects pure-timing mode 
while a value of 1 will conserve as much area as possible.
.PP
The \fB-i\fR option specifies that only the initial 2-input 
NAND decomposition be carried out.
.PP
The \fB-c\fR option specifies that one pass be carried out.
The new decomposition is always accepted, even if it results
in a slower circuit.
.PP
The \fB-T\fR option displays the delay as the iterations progress.
.PP
The \fB-a #\fR option tries to do the specified number of attempts
when restructuring a node. By default the algorithm tries only
one attempt at the restructuring. This option is for experimental
use at this stage.
.PP
The \fB-v\fR and \fB-D\fR options display debugging information.
