119 lines
6.0 KiB
C++
119 lines
6.0 KiB
C++
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// -*- C++ -*-
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namespace Kite {
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/*! \class TrackSegmentCost
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* \brief The cost calculator of a TrackSegment.
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*
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* \section secMiscAttributes Miscellaneous attributes
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*
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* Net instead of \TrackSegment : what we will access the most is the
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* \TrackSegment owner, so it's it we keep as an attribute. The consequence
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* beeing that the update member function should be given the \TrackSegment
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* as argument.
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*
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*
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* \section secBoundInterval Bound interval cost component
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*
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* This is the minimal interval to which the \TrackSegment can be
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* shrunk without breaking the net's connexity. The interval is
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* computed by AutoSegment::getTopologicalInfos(). And the computation
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* is as follow :
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* <ol>
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* <li>Each AutoContact has a <em>constraint box</em> which defines
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* the legal area where the AutoContact could be positionned.
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* <li>The <em>left bound</em> is the minimum of all constraints
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* boxes max.
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* <li>Conversely, the <em>right bound</em> is the maximum of all
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* constraints boxes min.
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* </ol>
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* \image html TrackSegmentCost-1.png "Left bound & right bound"
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* \image latex TrackSegmentCost-1.pdf "Left bound & right bound" width=0.6\textwidth
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*
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* \image html TrackSegmentCost-2.png "Maximal shrink example"
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* \image latex TrackSegmentCost-2.pdf "Maximal shrink example" width=0.6\textwidth
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*
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*
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* \section secCostAttractors Attractors and differential wirelength cost component
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*
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* The goal of attractors is to compute the wirelength variation whenever
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* the \TrackSegment changes of supporting \Track.
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*
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* The \TrackSegment is connected to perpandicular \TrackSegment, attractors
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* are the extremity position of those perpandicular <em>which are not</em>
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* connected to the reference \TrackSegment. The true rule is more complex
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* an is computed by AutoSegment::isTopologicalBound().
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*
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* \image html TrackSegmentCost-3.png "Attractors example"
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* \image latex TrackSegmentCost-3.pdf "Attractors example" width=0.6\textwidth
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*
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* In the attractor example, the reference horizontal \TrackSegment (in
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* black) which is made of (at least) three \c AutoSegments, is connected
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* to five vertical canonical \TrackSegment (labelled \e A through \e E).
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*
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* \e Left attractors are below the horizontal \TrackSegment axis,
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* \e right ones are above. Punctual attractors are exactly on the axis.
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*
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* As both \TrackSegment and \c AutoSegment are orienteds, source is always
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* the minimum and target always the maximum.
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*
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* The attractors are deduced as follow :
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* <ul>
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* <li>\e A : source is on the axis and move with it, so it is not took
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* into account. Target <code>\@2:19</code> is a right attractor.
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* <li>\e B : not aligned due to constraints on \e A, fully included in
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* \e A, do not generate attractor.
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* <li>\e C : canonical is accross the reference horizontal, both source
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* and target generate attractors : <code>left \@7:6</code> and
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* <code>right \@7:16</code>.
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* <li>\e D : punctual, that is null-length canonical exactly on the
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* axis. Generate only one attractor : <code>punctual \@14:10</code>
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* (i.e. not one for each extremity).
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* <li>\e E : target is on the axis and move with it, so it is not took
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* into account. Target <code>\@23:4</code> is a left attractor.
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* </ul>
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* The concept of left/right and punctual flavor for attractors are only
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* used dured construction. Once built only the coordinate remains.
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*
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* The extremity of perpandicular canonical \TrackSegment connected to
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* the reference segment do not generate attractors because they move
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* with it. But there are exception to this behavior : one is that
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* the extremity is in fact anchored to a terminal and will not move.
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* This is the work of the AutoSegment::isTopologicalBound() function
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* to check for thoses exceptions, in which case an attractor will be
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* created.
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*
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*
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* \section secTerminalCount The terminal count cost component
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*
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* The number of terminals directly connected to this \TrackSegment.
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* Computation relies on AutoSegment::getTerminalCount().
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*/
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/*! \function Net* TrackSegmentCost::getNet () const;
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* \Return The Net owning this TrackSegment.
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*/
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/*! \function unsigned int TrackSegmentCost::getTerminals () const;
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* \Return The number of terminal directly connected to this \TrackSegment.
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*/
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/*! \function DbU::Unit TrackSegmentCost::getWiringDelta ( DbU::Unit axis ) const;
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* \param axis The axis where to put the TrackSegment.
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*
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* \return The total wirelengh needed for perpandicular TrackSegment to connect
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* with this one sets on <em>axis</em>. The sum of distance to all the
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* attractors.
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*/
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/*! \function void TrackSegmentCost::update ( TrackSegment* trackSegment );
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* \param trackSegment the associated \TrackSegment, must be the same as used
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* in the construction.
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*
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* Update the cost calculator after a relative position change.
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*/
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} // End of Kite namespace.
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