130 lines
7.0 KiB
C++
130 lines
7.0 KiB
C++
// -*- C++ -*-
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namespace Kite {
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/*! \class TrackSegment
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* \brief Derived Katabatic::AutoSegment for the router.
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*
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* \image html TrackSegment-10.png "Fig 1: TrackSegment Context"
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*
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* We create one TrackSegment per aligned Katabatic::AutoSegment set,
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* the TrackSegment is associated to the canonical one of the set.
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*
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* To provide some speedup, the full extention of the aligned segment
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* set is computed once and stored in the TrackSegment itself.
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* The drawback beeing that whenever one segment from the aligned
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* set has it's extention modified, the full extention must be
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* recomputed.
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*
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*
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* \section secTSLazyRevalidate Lazy Revalidate
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*
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* When the TrackSegment::revalidate() method is called, it only update
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* the cached size of the segment (from the AutoSegment set of aligneds)
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* and the track into which it may be inserted.
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*
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* The associated DataNegociate and RoutingEvent are \b not updated.
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* - The RoutingEvent will be updated when it's key is updated,
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* typically during a requeueing operation \b and in the
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* SegmentFsm constructor. This should be optimzed in the future.
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* - The DataNegociate is updated \e only in the SegmentFsm
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* constructor. This is the most costly of the two updates as
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* it perform a perpandicular & parallel connexity exploration.
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*
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*
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* \section secDogleg Dogleg Management
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*
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* The basic AutoSegment::canDogleg() method is declined in three more
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* dedicated methods in this class:
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* - TrackSegment::canDogleg(), for locals only, check if a break
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* is possible, never break a segment more than once (to avoid
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* fragmentation).
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* - TrackSegment::canDogleg(Katabatic::GCell*,unsigned int flags)
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* for globals, check that the segment is breakable in the desired
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* GCell. Never break twice in the first/last GCell (fragmentation
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* limitation), but may \e reuse an already existing dogleg.
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* - TrackSegment::canDogleg(Interval), for locals only, direct proxy
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* for the AutoSegment method. Never allow more than one break.
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*
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* <b>Relationship between AutoSegment and TrackSegment</b>
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*
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* Figure 2 below, shows an example of dogleg creation:
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* - At the Katabatic level, AutoSegment \c id:12 is broken. Thus
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* the creation of AutoSegments \c id:20 and \c id:21. As per
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* specification, the orignal segment \c id:10 remains on the
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* left side (source) of the break.
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* - But, because the canonical of the former aligned AutoSegment
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* set \c (10,11,12,13,14) was on the \e right side of the break,
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* the new parallel TrackSegment will be created on the \c left
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* side, associated to the newly promoted canonical AutoSegment
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* \c id:12.
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*
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* \image html _makeDogleg-10.png "Fig 2: Dogleg Management"
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*
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* The TrackSegment::_postDoglegs() method called by all flavors of
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* TrackSegment::makeDogleg() methods is responsible for creating new
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* TrackSegments for the new doglegs (there may be more than one), it
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* also update the dogleg level and source/target dogleg flags.
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*
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* \redB{This section is not finished.} I need to review the parent and
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* doglevel numbering management. There seems to be a risk of infinite
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* fragmentation as the numbering of the original segment is not
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* increased, we should create a \e break counter separate from
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* deepness.
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*
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*
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* \section secWeakGlobal Global, Weak Global and Local Segments
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*
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* There's a slight semantic change between Katabatic and Kite about
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* what is local and what is local. This is due to how we consider the
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* intermediate status of \e WeakGlobal.
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*
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* A \c WeakGlobal segment is a local segment which is aligned with a
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* global (though a VTee or an HTee contact).
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*
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* In Katabatic a local segment is one that is not \c Global, a local segment
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* can be both \c Local and \c WeakGlobal.
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*
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* In Kite a local segment is one that is neither \c Global or \c WeakGlobal.
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* The \c WeakGlobal sides with \c Global unlike in Katabatic.
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*
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*/
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//! \function static TrackSegment* TrackSegment::create ( AutoSegment* segment, Track* track, bool& created );
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//! \param segment The Katabatic AutoSegment to decorate.
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//! \param track A Track into which insert the TrackSegment (may be \NULL).
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//! \param created This flag is sets is a new TrackSegment has be created.
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//! \return A TrackSegment wrapped around an AutoSegment.
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//!
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//! Constructor mainly used at loading time to decorate the Katabatic
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//! data-base with the router attributes.
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//! \function unsigned long TrackElement::getFreedomDegree() const;
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//! \sreturn The degree of freedom of the element. It is used as a priority value
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//! when sorting TrackElement (in RoutingEvent).
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//!
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//! Currently, it is the \e slack of the Katabatic::AutoSegment.
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//! \function void TrackSegment::revalidate ();
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//! Actualize the TrackSegment characteristics from the supporting
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//! elements (set of AutoSegment).
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//!
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//! This method do not update the DataNegociate or the RoutingEvent.
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//! This is a lazy update delayed until the constructor of SegmentFsm is called.
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//! (see \ref secTSLazyRevalidate "Lazy Revalidate").
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//! \function TrackSegment* TrackSegment::_postDoglegs ( TrackElement*& perpandicular, TrackElement*& parallel );
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//! Post-process to be called inside the various dogleg creation or slacken
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//! methods. Iterate through the newly created AutoSegments to create, for
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//! the <em>perpandicular</em> and the <em>new parallel</em> associateds
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//! TrackSegments. Also sets the dogleg levels and flags of the newly
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//! created elements.
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//!
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//! The session dogleg reset is called at the end of this method. The \c perpandicular
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//! and \c parallel references to pointers contains the newly created segments
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//! for the \b last dogleg. If more than one was created, you cannot access them
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//! (the need has not arised yet).
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}
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