144 lines
7.0 KiB
C++
144 lines
7.0 KiB
C++
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// -*- C++ -*-
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namespace Katabatic {
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/*! \defgroup layerAssign 4. Layer Assignment (internal)
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*
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* This modules documents how layer assignment is performed. It is intented
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* for developpers only.
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*
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* Layer Assignment functions works in two steps :
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* <ol>
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* <li>For a given net, go through the \c AutoSegment and migrate them
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* to upper (global) layers if needed.
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* <li>For each \c AutoContact of which at least one \c AutoSegment has been
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* migrated, split the \c AutoContact (with SplitAutoContact()).
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* </ol>
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*
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* SplitAutoContact() relies on the hypothesis that the split occurs
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* between two sets of \b HV layers. For example between \b M2/M3 and
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* \b M4/M5 but not between \b M2/M3 and \b M6/M7.
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*
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* The following figures shows all possible configurations, except for
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* the most obvious : when all \c AutoSegment are migrated from \b M2/M3 to
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* \b M4/M5 we just change the layer of the \c AutoContact from \b C23 to \b C34.
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* SplitAutoContact() compute the <em>layer span</em> of the AutoContact,
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* that is, the distance between the lowest layer and the higher one (it
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* cannot exceed 3 as from \b M2 to \b M5). Then it detach the higher
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* \c AutoSegment and re-attach them to a newly created \c AutoContact.
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* In turn this new \c AutoContact is connected to the previous one.
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* <ul>
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* <li>The span is 3 (\b M2 to \b M5) : creates 2 \c AutoContact and
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* 2 \c AutoSegment.
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* <li>The span is 2 (\b M2 to \b M4 or \b M3 to \b M5) : creates one
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* \c AutoContact and one \c AutoSegment.
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* <li>The span is 1 (\b M3 to \b M4) : just change the layer of the
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* \c AutoContact to \b C34.
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* </ul>
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* Simpler rules could be formulated : if \b M2 is present creates the
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* \b M3 additionnal \c AutoSegment. If \b M5 is present, created the
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* \b M4 additionnal \c AutoSegment.
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*
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* In <b>M2+M3+M4+M5</b>, <b>M3+M4+M5</b> and <b>M2+M3+M4</b> configurations
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* two separates \b M4 \c AutoSegment (resp. \b M3 \c AutoSegment) are needed
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* to avoid the <em>incomplete AutoContact wiring</em> problem
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* (see \ref ssecFaultyTopologies).
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*
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* \image html SplitAutoContact-1.png "Full Configuration"
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* \image latex SplitAutoContact-1.pdf "Full Configuration" width=0.4\textwidth
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* \image html SplitAutoContact-2.png "No M3 Configuration"
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* \image latex SplitAutoContact-2.pdf "No M3 Configuration" width=0.4\textwidth
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* \image html SplitAutoContact-3.png "No M3,M4 Configuration"
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* \image latex SplitAutoContact-3.pdf "No M3,M4 Configuration" width=0.4\textwidth
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* \image html SplitAutoContact-4.png "No M2 Configuration (degenerate)"
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* \image latex SplitAutoContact-4.pdf "No M2 Configuration (degenerate)" width=0.4\textwidth
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* \image html SplitAutoContact-5.png "No M5 Configuration (degenerate)"
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* \image latex SplitAutoContact-5.pdf "No M5 Configuration (degenerate)" width=0.4\textwidth
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* \image html SplitAutoContact-6.png "No M2,M5 Configuration (degenerate)"
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* \image latex SplitAutoContact-6.pdf "No M2,M5 Configuration (degenerate)" width=0.4\textwidth
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*/
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/*! \enum LayerAssignMethod
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* List all avalaible global layer assignment algorithm avalaible for
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* layerAssign().
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*/
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/*! \var LayerAssign LayerAssignByLength
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* See layerAssign().
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*/
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/*! \var LayerAssign LayerAssignByTrunk
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* See layerAssign().
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*/
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/*! \function void KatabaticEngine::layerAssign ( unsigned int method )
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* \param method specify the algorithm used to perform the layer assignement.
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*
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* The loadGlobalRouting() method build a topology for each net using only the
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* two first routing layers avalaibles (usually \e metal2 and \e metal3).
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* To use upper routing layer we needs to go through a <em>layer assignment</em>
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* step. The layerAssign() method provides two simples approaches to do so :
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* <ul>
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* <li> layerAssignByLength : every global AutoSegment which
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* length is superior to the global threshold is moved to the upper layer.
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* <li> layerAssignByTrunk : if any AutoSegment of a net
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* exceed the global threshold, then all the global wiring of this
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* net is put into the upper layers.
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* </ul>
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*
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* This method is a switch to _layerAssignByLength() or _layerAssignByTrunk().
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*
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* The <em>global threshold</em> is to be sets using the setGlobalThreshold()
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* method.
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*/
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//! \addtogroup layerAssign
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//! \{
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/*! \function void KatabaticEngine::_layerAssignByLength ( unsigned long& total, unsigned long& global, set<Net*>& globalNets );
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*
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* Perform the layer assignment on all nets, using the
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* layerAssignByLength algorithm. See layerAssign().
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*/
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/*! \function void KatabaticEngine::_layerAssignByLength ( Net* net, unsigned long& total, unsigned long& global, set<Net*>& globalNets );
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* \param net The net to process.
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* \param total The total number of AutoSegment.
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* \param global The number of AutoSegment that have been sets global.
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* \param globalNets Set of global Nets.
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*
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* Perform the layer assignment on one net, using the
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* layerAssignByLength algorithm. See layerAssign().
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*/
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/*! \function void KatabaticEngine::_layerAssignByTrunk ( unsigned long& total, unsigned long& global, set<Net*>& globalNets );
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*
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* Perform the layer assignment on all nets, using the
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* layerAssignByTrunk algorithm. See layerAssign().
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*/
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/*! \function void KatabaticEngine::_layerAssignByTrunk ( Net* net, unsigned long& total, unsigned long& global, set<Net*>& globalNets );
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* \param net The net to process.
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* \param total The total number of AutoSegment.
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* \param global The number of AutoSegment that have been sets global.
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* \param globalNets Set of global Nets.
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*
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* Perform the layer assignment on one net, using the
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* layerAssignByTrunk algorithm. See layerAssign().
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*/
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//! \}
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}
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namespace {
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}
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