* Bug: In LefImport::_macroCbk(), the GDS file must be loaded *before*
we start putting nets & components from the LEF file. The GDS parser
must find an blank slate and not try to modifies nets already
created by LEF.
This way, we really can modify the GDS layout to suit the LEF
statements.
Note that we may end up with two set of terminal exactly overlapping,
a Pad from the GDS and a Segment from LEF.
* Change: In GdsParser::xyToPath(), we were creating articulated layout
segments over contacts using the "all_nets_merged_in_gds" common net.
But some segment may later be promoted to interface, that means
deleting the previous one and re-creating it with the right
external net.
The deletion was automatically creating a rubber between it's two
Contact anchors. And we there is no way to get rid of it (other than
also removing the Contacts).
* New: In LefImport, add setGdsForeignDirectory() to point out from where
to load the extra GDS file in case a FOREIGN directory is present
in MACRO.
Also add support for merging the supply nets. It may happens that
the supply nets have different names in the GDS ("vdd!") and LEF files
("pvdd"), in that case, the LEF name supersede the GDS one.
The GDS file will be loaded *first* then completed by the LEF contents.
Blockage in the GDS file are *not* loaded.
* Change: In GdsParser, perform an early recognition of supply nets. For now
it's hardwired to names starting by "vdd" and "gnd", but should be
parametrized in the future.
Needed for the LefImport to merge, if needed, the power supplies.
In GdsStream::xyToComponent(), skip the blockage if required.
* Change: In LefImport::_pinCbk(), if a pin has "USE POWER" or "USE GROUND"
make it a global signal (previously flagged only "!" appended to name).
* Change: In LefImport::_pinStdPostProcess() do not try to find "on grid"
components for supply nets, just make all their components externals.
* New: In LefImport::LefParser, add support for LEF Polygons that are
translated into Hurricane Rectilinears.
* Change: In LefImport::setMergeLibrary(), the default behavior for the
LEF parser is to create a new separate library under LEF/<lib_name>
for each file. But if the various cells are put each one in it's own
cell, this is suitable. So we can now set a library beforehand into
which they will be all put.
* New: in CRL/technos.node180.gf180mcu, configuration files for the
GF180MCU open PDK.
* New: in cumulus/designflow.technos, added a setupGF180MCU_GF() to
initialize the GF PDK.
* Move all Python stuff under a common Python namespace "coriolis".
* Instead of having a series subtrees for each tool, integrate
everything in one common tree. So now, all components can be
located either with an absolute path from "coriolis" or, inside
cross-reference themselves through relatives imports.
* As a consequence, we only need to add ".../site-packages/coriolis/"
to the PYTHONPATH, and not a whole bunch of subdirectories.
And nothing, if installed in-system.
* The tree of free technologies configuration files is also moved
below "coriolis/technos" instead of "/etc".
* Supressed "cumulus" level for the plugins.
* All python modules are rewritten using relative imports except
for the configuration files that uses absolute import as they
can be cloned outside of the tree to serve as templates.
* Change: In boostrap/FindPythonSitePackages, include "/coriolis" in
Python_CORIOLISARCH and Python_CORIOLISLIB.
Provide a Python_SITELIB *without* "/coriolis" appended.
* Change: In cumulus/plugins/__init__.loadPlugins(), must prefix modules
read in the plugins directory by "coriolis.plugins.". No longer need
to add their path to sys.path.
* Change: In crlcore/python/technos/nodeX/*/devices.py, the scripts of
the layouts generators must be prefixed by "coriolis.oroshi.".
* Change: In CRL::System CTOR, no longer add the pathes of the various
plugins to sys.path. Only "site-packages/coriolis/".
* New: In Utilities::Path::toPyModePath(), new method to convert a
filesystem path into a python module path.
Examples:
"coriolis/plugins/block" --> "coriolis.plugins.block".
"coriolis/plugins/rsave.py" --> "coriolis.plugins.rsave".
* Change: In katanaEngine::_runKatanaEngine(), rename the hook script
initHook.py. No longer need to modify sys.path.
* Change: In BoraEngine::_runBoraEngine(), rename the hook script
initHook.py. No longer need to modify sys.path.
* Change: In UnicornGui::_runUnicornInit(), rename the hook script
initHook.py. No longer need to modify sys.path.
* Change: In cumulus.plugins.chip.constants, put the constants
outside __init__.py to avoid a loop at initialization.
* New: In CRL::RoutingLayerGauge, two new types of gauge are supported:
- Unusable : just do nothing with it, but the layer is stacked.
- BottomPowersupply : can be used for supply routing only, and
is *below* the normal routing layers (instead of on top as
usual).
Both new types must be *below* the real routing layers.
* New: In CRL::RoutingGauge, add a new attribute "firstRoutingLayer"
to give the index (depth) of the first layer usable for routing.
(not Unusable and not BottomPowerSupply)
* New: In Anabatic::Session & Anabatic::NetBuilder, in order to build
the initial wiring, provides (Session) and use (NetBuilder) the
new functions:
- getBuildRoutingLayer(depth)
- getBuildContactLayer(depth)
Thoses functions takes into account (offset) the unusable layers
so depth 0 is the first usable routing layer, and so on.
* New: In Technology, in order to support symbolic technology on top
of a real technology using non-generic layer names, it comes in
handy to be able to define layer alias names. Generic *real*
layer names could be defined as alias over the technology
specific ones. Then, we can build the symbolic layers upon
the generic names (so *that* part of the init code can be
shared between techs).
Adds Technology::addLayerAlias()
The semantic of Technology::getLayer() changes a little, it
return the techno layer associtated to the name *or* the
aliased name.
* Bug: In Technology::_addPhysicalRule(), in case of a rule redefinition,
we were using it's name *after* the deletion of the rule object.
Nasty crash.
Improve the error message by giving the name of the conflicting
rule.
* In CRL/helpers.analogtechno, add an addDevice() function to load
analogic devices descriptors (copied from the old init system).
* In CRL/ApParser, if an exception is catched, tells in which file and
line it did occur.
* In Oroshi/dtr.Rules, add a translation step to get the rule names
from the technology. From generic names to actual technology
layer names.
Add some documentation.
* In Oroshi/stack.Stack, get the layers names through dtr.Rules to get
the layers names translated.
Previously, the relevant NetBuilder and routing strategies where
directly guessed from the RoutingGauge traits. This is no longer
doable as the combinations increases. Now to configure both the
global and detailed router we need three "parameters" :
1. The routing gauge itself (tells which layers are in which
directions) and how to make the VIAs.
2. The NetBuilder to use, they are identified by strings.
Currently we support:
* "HV,3RL+", for all SxLib derived standard cells.
* "VH,2RL", for hybrid routing (over the cell, but terminals
are also in the first RL).
* "2RL-", for strict channel routing.
* "VH,3RL+", an attempt for FreePDK 45, not optimized enough
to be considered as usable.
3. The routing style, mostly affect the way the GCell grid will be
built.
* VH : first RL is V.
* HV : first RL is H.
* OTH : Run in full over-the-cell mode (needs at least 3RL).
* Channel : Run in *strict* channel routing mode (no routing over
the standard cells).
* Hybrid : Create channels, but can use H tracks over the
standard cells.
Thoses three parameters are partly overlapping and must be sets in
a consistent manner, otherwise strange results may occurs.
* New: CRL::RoutingGauge::getFirstRoutingGauge(), to get the lowest
layer available for routing (not a PinOnly, not a PowerSupply).
* Change: In CRL::RoutingGauge::isHV() and isVH(), were previously
always returning false when the gauge was 2RL only. Now, check
on the first usable RL.
* Bug: In cumulus/plugins.block.configuration._loadRoutingGauge(),
there was a bad computation of the deep RLs when the top layer
was not defined. Occured for 2RL gauges only.
* Bug: In Anabatic::RpsInRow::slacken() (LayerAssign), forgotten curly braces
in the test to skip METAL2 terminals.
* Change: In Etestian::BloatChannel::getDx(), adjust the bloating
policy to converge on Arlet6502. Always ensure that there is
a 50% ratio between terminal used V-tracks and free ones.
If there is more than 80% of terminals, add one more track.
* Bug: In AnabaticEngine & KatanaEngine, KatanaEngine is a derived
class of AnabaticEngine. They uses Anabatic::Configuration
and Katana::Configuration that also derives from each other.
I though I had made one configuration attribute in the base
class that was using the right Configuration. But no. I did
have two configurations attributes, one in AnabaticEngine and
one in KatanaEngine, the later "shadowing" the former. As a
results, parameters modified in AnabaticEngine, *after* the
initial creation of the tool *where never seen* at Katana
level (due to it's own duplicate). What a mess.
Now there is only one attribute in the *base* class Anabatic,
which is created through a new virtual function _createConfiguration()
called in _postCreate() which allocate the right Configuration
according to the dynamic type of the tool (KatanaEngine).
In KatanaEngine, access the configuration through the
attribute (_configuration) and not the accessor (getConfiguration()).
* Bug: In KatanaEngine, no longer directly use the _configuration attribute
(which is not accessible anyway) but the getConfiguration() accessor.
The accessor perform a static_cast from the Super::getConfiguration()
into Katana::Configuration.
Complete cleanup of the various configuration accessors.
* New: AnabaticEngine::setupNetBuilder(), perform an early check
of the requested NetBuilderStyle. The NetBuilderStyle is just a
string that will be matched against the (hard-coded) supported
NetBuilders. Then check the topological characteristics against
the capabilities of the gauge (HV, VH and so on).
Still a bit too hard-coded for now.
This function has been split from AnabaticEngine::_loadGrByNet().
* Change: AnabaticEngine::isChannelStyle() renamed from isChannelMode().
* New: In Anabatic::Configuration, two new attributes to select the
topology and routing style:
- _netBuilderStyle to explicitely select the NetBuilder to use.
It's a string, which is provided by each NetBuilder.
- _routingStyle to define how the overall routing will work.
It's a set of flags (StyleFlags):
* VH : first RL is V.
* HV : first RL is H.
* OTH : Run in full over-the-cell mode (needs at least 3RL).
* Channel : Run in *strict* channel routing mode (no routing over
the standard cells).
* Hybrid : Create channels, but can use H tracks over the
standard cells.
* New: In anabatic/Constants, add StyleFlags to define how the router
should operate (see above).
* Bug: In Anabatic::GCell, in CTOR, no reason to set up the HChannelGCell flag.
* Bug: In Anabatic::GCell::updateDensity(), when computing layers non contiguous
saturation, do not systematically skip RL 0, but only if it's PinOnly.
* Change: In Anabatic::NetBuilder, rename isTwoMetal by isStrictChannel.
* Change: In Anabatic::NetBuilderHV, rename doRp_AccessNorthPin() in
doRp_AccessNorthSouthPin(). More accurate.
* Bug: In NetBuilderHV::_do_1G_xM1_1PinM2(), the wires to connect the M1
terminals where created *twice*. Uterly stupid, there where placed in
overlap by the router!
* New: In AnabaticEngine, new accessors to the NetBuilderStyle and
RoutingStyle, proxies towards Configuration.
* Bug: In Manipulator::relax(), if there are two doglegs to be done, but
they are in the same GCell, only do one (the conflicting interval)
is short.
* Change: In Katana::Session, rename isChannelMode() into isChannelStyle().
* Change: In TrackSegment::isUnbreakable() and isStrap(), return false
when the base segment is a *weak global* (aligned with a global one).
* Change: In Katana::Row::createChannel(), correctly distinguish between
*strict channel* style and *hybrid* style. Tag the GCells as std cells
row or channels only in the former case.
* New: In CRL::DefExport, checkStatus() has a second argument to display
a more comprehensive error message.
Applied throughout all the DEF callbacks.
* Bug: In CRL::DefExport, the UNIT statement and associated toDefUnits()
functions where wrong. Now always use a UNITS of 1000 in microns.
Then toDefUnits() converts DbU into microns and multiply by 1000.
* Change: In CRL::defExport::_netCbk(), enable the net name renaming
only when the ProtectNetNames flag is set.
* New: In CRL::PyDefExport, also export the flag values to Python.
* Change: In CRL::LefImport::LefParser, layers defined in the LEF file
are matched *in order* to the ones from the technology *in order*
(not by name matching). But if there is a mismatch, that is more
layers in the techno than in LEF, we got a shift. Now we can tell
the parser to ignore a set of layers by setting up the configuration
variable:
LefImport.unmatchedLayers = 'DIFFP,POLY2,SMURF'
* In CRL::GdsStream::_staticInit(), all the layers where added to the
translation table, whether or not they where configured for the
GDS stream. So the non GDS configured layers got a GDS layer
id of 0 and were using this case. Either overwriting the legit
layer or creating a new one while it should have been invalid.
Now we check for the hasGds() predicate of the layers.
* In CRL::GdsStream, add a new option to tell that, layer id 0,
if undefined, may be used as the definition of the boudary of
the cell (abutment box).
* In CRL::PyGds, now also export the flags to the Python interface.
* Update: In CRL/node600/phenitec/kite.py, update the routing gauge to
the new format. So now we can use again SxLib-2M (channel routing
SxLib for two metal technologies).
* Change: In CRL::BlifParser, if a master cell is not found in the
AllianceFramework, then try in the Blif supplied libraries.
This is used to load the zero, one and tie cells.
Add a Blif::getCell() static function to look into the Blif
supplied libraries.
* Change: In CRL::LefImport, sometimes there can be discrepencies between
the LEF ROUTING layers and the Coriolis routing gauge. Now ignore
routing layers that are *not* presents in the Coriolis gauge.
* Change: In AnabaticEngine, moved routingMode attribute from KatanaEngine,
as some setup operations needs it.
* Change: In AutoSegment::canReduce(), allow fixed segments to be reduced
if they are "jumpers" (turn+turn and top+top or bot+bot).
This case arise on the edge of routing channels for fixed wires
to connect terminals.
* Change: In AutoSegment::getTopologicalinfos(), compute differently the
(leftBound,rightBound) interval when in channel mode.
In over-the-cell mode, this interval is the one of the whole
GCells under the wire. In channel mode, for fixed wires (that is,
verticals connecteds to cells) this interval is reduced to half
the GCell height, on the connected side of said channel.
This allows Manipulator::_insertToTrack() to issue disantangling
requests (push left/push right) for fixed segments that are face
to face in the channel.
* Change: In Anabatic::Configuration CTOR, allow the cellGauge to have a
different name from the routingGauge. Now if the cell gauge that
should match the routing gauge is not found, fallback to the
name set in "anabatic.cellGauge" parameter.
Case occur when we try to match with CORE sites from LEF files.
* Change: In Etesian::Configuration CTOR, same change as in the
Anabatic configuration.
* Change: In Anabatic::GCell::updateDensity(), never set the GoStraight
flag in channel mode. This flag makes sense when there is at least
4 routing layers (so we have 2 contiguous free of blockages).
* Bug: In Anabatic::Session::_getNearestGridpoint(), sometimes the nearest on
grid point is outside the constraint box. Now force the point
to remains inside constraints even if offgrid.
* Change: In Katana::DataNegociate::update(), perpandiculars that are
either reduced or in non-preferred routing direction should not
trigger a bug message.
* Change: In KatanaEngine::_check(), do not check for fixed, horizontal
non-prefs AutoSegments in channel mode (avoid false bug display).
* Bug: In Manipulator::_forceToTrack(), slighty shrink (-1) the interval
to free. The intersection function of intervals returns true when
the two intervals *exactly* touches (1.vMax == 2.vMin). But in
this specific case, they are not *overlapping* and no action
should be taken...
* Bug: In Manipulator::_insertInTrack(), do not reject the track when
we are overlapping a fixed vertical segment in channel mode.
(Hmm, maybe already corrected by the previous one).
* Change: In Katana::NegociateOverlapCost(), in channel mode, do
not put two overlaping vertical fixed segments into infinite cost.
This happens when two cell connected verticals are face to face in
a channel. We want them negociated the track (by shrinking their
length) instead of excluding it right away.
* Change: In NegociateWindow::createTrackSegment(), in channel mode,
do not attempt to create a track segment over a fixed and reduced
AutoSegment.
Do not attempt to put a non-preferred AutoSegment on a Track
either.
* Bug: In RoutingEvent::revalidate(), the number of availables tracks
was badly computed when in the pure constraint case, when there
was only one it was reporting zero.
* Change: In TrackElements::TrackElements_Perpandicular::Locator,
do not issue a bug when an non-pref or reduced AutoSegment do not
have an associated TrackElement.
* Change: In TrackSegmentCost::update(), do not issue a bug when a
perpandicular is reduded or non-pref and do not have a TrackElement.
* Bug: In cumulus/plugins/rsave.py, the Cells where saveds each time
one instance of was encountered. Resulting in multiple saves.
It was, of course, ineficient, but it also triggers a bug
that seems to happen after multiple save : the VHDL additional
property was deleted *before* the full hierarchical dump was
finished.
Now, we save each Cell only once so it does not occur, but
should make a deeper investigation later.
The decoupling of the cell gauge and the routing gauge implies that
the METAL2 & METAL3 terminals of macro blocks cannot be aligned on
the routing tracks anymore. That is, an horizontal METAL2 terminal
will not be on a track axis, but offgrid, so we no longer can use
a METAL2 horizontal segment to connect to it. Making an adjustement
between the offgrid terminal and the on-grid segment has proven
too complex and generating difficult configuration for the router.
Moreover, METLA2 terminal could be fully inside a METAL2 blockage.
So now, when the gauges are decoupled, we connect the METAL2 and
METAL3 the same way we do for METAL1: *from above* in the perpandicular
direction and using a *sliding* VIA. We assume that those kind of
terminals in upper metals are quite long.
* New: In Hurricane::Rectilinear, export the isNonRectangle() method
to the Python interface.
* New: In CRL::RoutingGauge, add function isSuperPitched() with the
associated boolean attribute. Set to true when each pitch of
each layer is independant (not low fractional multiples).
* New: In AnabaticEngine, add the ability to temporarily disable the
canonize() operation (mainly used in dogleg creation).
* New: In AutoSegment::canonize(), do nothing if the operation is
disabled by AnabaticEngine.
* Bug: In Session::_revalidateTopology(), disable the canonization
during the topology updating of a net. Too early canonization
was occuring in makeDogleg() leading to incoherencies when
performing the later canonization stage over the complete net.
Mostly occured in the initial build stage of the net.
* New: In GCell, add function postGlobalAnnotate(), if a layer
is fully blocked (above 0.9), typically, under a blockage,
add a further capacity decrease of 2 on the edges. So we may
handle a modicum of doglegs.
* Bug; In GCell::addBlockage(), removeContact(), removeHSegment()
and removeVSegment(), forgot to set the Invalidated flag.
This may have lead to innacurate densities.
* Change: In GCell::updateDensity(), more complex setting of the
GoStraight flag. This flag is now set if we don't have two
*contiguous* below 60% of density. We need free contiguous
layers to make doglegs.
* New: In NetBuilder, now manage a current state flag along
with the state flag of the *source* GCell. This flag is used
to tell if the GCell needs it's *global* routing to be done
using the upper layers (METAL4 & METAL5) instead of the
lower ones.
* New: In NetBuilder::setStartHook(), set the state flag of the
GCell to ToUpperRouting when processing a global routing
articulation and one of the base layer is obstructed
above 0.9.
In GCell with terminals, also set ToUpperRouting when there
are some in METAL2 / METAL3 and the gauge is not super-pitched.
* New: In NetBuilder, function isInsideBlockage(), to check if a
terminal is completely or partially enclosed in a blockage.
* Change: In NetBuilderHV::doRp_AutoContact(), remove support for
trying to put on grid misaligned METAL2/METAL3.
Instead systematically access them from above.
Do not cover with fixed protection terminals that are already
enclosed in blockages.
* Bug: In NetBuilderHV::doRp_AutoContact(), always add the terminal
contact in the requested GCell and not the target/source one,
in case the terminal span several GCells.
* Change: In NetBuilderHV::doRp_Access(), create the local wiring
according to the RoutingPad layer.
* Change: In NetBuilderHV::_do_xG(), _do_2G(),
create the global wiring in upper layers, according to the
ToUpperRouting flag.
* Change: In NetBuilderHV::_do_xG_xM3(), now delegate to
_do_xG_xM3_baseRouting() and _do_xG_xM3_upperRouting() if the
density at terminal level is above 0.5.
* New: NetBuilderHV::_do_xG_xM3_baseRouting() and
_do_xG_xM3_upperRouting() separated function to manage the
local routing.
* Change: In NetBuilder::_do_globalSegment(), if the currently
processed GCell or it's source is in ToUpperRouting mode,
move up the global segment. Do *not* use the moveUp() function
which would create doglegs unwanted at this stage.
* New: In KatanaEngine::annotateGlobalGraph(), call postGlobalAnnotate()
on the GCell after the blockages have been taken into accound to
add the penalty.
* Bug: In Track::getPrevious(), correctly manage the 0 value for the
index argument. Strange it didn't show earlier.
Same goes for Track::expandFreeInterval().
After a Cell has been created in memory (by parsers or Python scripts)
we can annotate it with the Spice parser so it will know the right
order with which to create the subcircuit call ('x').
* New: In CRL::Spice::load(), add support to read the ".subckt" card
and guess the right ordering for generating the 'x' (subcircuit
card call).
* Bug: In Spice::SpiceBit & Spice::BitExtension, when a Net bit property
is removed, if it's the currently cached property in BitExtension
it may lead to a crash. So when a property is destroyed, we must
also clear the cache (see remove(), clearCache() & onReleasedby()).
I'm wary that this could also happen on other kind of cached
extensions...
* New: In CRL::NamingScheme, new method vhdlToVlog() to translate back
VHDL net name into Verilog. Currently only changes "()" into "[]".
Used to generate the commented SPICE interface for Alliance compliance.
* Change: In Spice::Entity, previously all the ordering where removed
between each run of the SPICE parser, but the orders read from
SPICE file (mostly standard cells) must be kept. So add a flag
ReferenceCell to prevent the removal by ::destroyAll().
* Bug: In CRL::BlifParser::Model CTOR, forgot to set the direction
on auto-generated power supply global nets. So they were put
in "linkage" in the VST files.
* New: In CRL::DefImport, add specific support for the Sky130/Caravel
harness "user_project_wrapper".Mainly:
- Do not fuse together "io_in" and "io_out" as a single net as
they should (according to the DEF). So we can connect separately
on each of them. We only allow one port for each net, as in VHDL.
* Bug: In CRL::MeasureSet::toStringHeaders(), check and issue a warning
if a measure label ends with a "." (dot).
* Change: In CRL::ToolEngine::getMeasure(), return the data measure
by pointer instead of by reference (easier to manipulate afterwards).
* New: In EtesianEngine::place(), add the placement runtime (under label
"placeT") to the measure set.
* New: In KatanaEngine::dumpMeasures(), add the Etesian runtime to the
set of measures.
WARNING: We are partially duplicating the informations pertaining
to the Alliance catalog (stored in the Catalog property)
directly into the Cell. This is needed for Flexlib which
is not using the Alliance loading mechanim. Ideally the
Catalog information should be moved into the Cell.
* New: In Cell, add new state flags Diode, PowerFeed (in addition to
Pad & Feed).
Export flags setter/getter to Python. For Flexlib usage.
* Change: In AllianceFramework::getInstancesCount(), correctly skip
Diode & Feeds based on Cell flags. Those flags must correctly
be set in the various Flexlib_fix.py scripts.
* New: In AllianceFramework::getInstancesCount(), add a flag TerminalNetlist
to stop recursion on "terminal for netlist" instance level. This is to
avoid counting physical only or non-routed instances inside hard macros,
like SRAM blocks. This was leading to an overstimation of the "size"
in number of gates of the routing problem.
* Change: In KatanaEngine CTOR, call for the terminal for netlist number of
gates...
* Bug: In all CMakeLists.txt, it seems I was doing a worng use of
target_link_library(). No longer add dependencies to the C++ base
library but instead either to the Python associated module or
to the final binaries. This was inderectly causing the linking
problem related to Python (which was a misdirection).
* Bug: Typo in FindLibexecinfo.cmake, do not use FindLib[E]xecinfo.
* Change: In CRL/ccore/CMakeLists.txt, activate SKIP_AUTOMOC on
bison/flex generated files.
* Bug: In viewer/PyHApplication, do not delete the C++ object in
the Python destroy method.
* New: In CRL::DefImport, the previous version of the parser was designed
only to read pure netlists, no physical components. Now add features
for:
* VIA generate statements. Generated VIAs are created as Cell and
then instaciated wherever they are needed. Alternative would be
to duplicate it's contents so the original netlist is not changed.
But would create lot more objects.
* PIN, added support for basic physical shapes.
* SPECIALNETS and their associated wiring (path callback).
Note: (to myself) As the Path is created *before* the NET or SPECIALNET
callback is called, we must create a temporary net to store
the path components. This is the "__prebuild__" net which
will be merged later with the actual net.
* Bug: In CRL::GdsDriver::GdsStream::operator<<(Cell*), when looking for
layer names ending with ".pin", must also check that the string is
at least 4 characters long.
Jean-Paul Chaput
Robert Taylor
gatecat
Myrtle Shah