this limited ports to 16384, which seemed reasonable at the time.
However, the sky130_sram_macro layouts connect power and ground in a
way that when coupled with "extract unique" can generate tens of
thousands of ports and overrun the bit field, showing that automation
can do the unexpected. The solution was to split out the port number
from the label record as its own 32-bit value.
an optional extra argument to the "select" command that can be used
to select labels by glob-style matching; e.g., "select area labels
VSS*" or "select less area labels *_1". This will help in managing
labels after flattening a standard cell design; e.g., by using
"select less area labels */VDD".
checks on non-Manhattan tiles were made only on the straight edges;
this was sufficient for most checks. However, it can miss the case
of facing non-Manhattan edges. This check does not do triggered
rules because there is no non-Manhattan maxwidth algorithm implemented,
and because the triggering clipping area is a triangle and needs an
extension to support it.
one is an "off_grid" DRC type, which can be used to check geometry
that is below the manufacturing grid. Normally magic prevents the
grid from being subdivided below the manufacturing grid, but this
limit can be removed and replaced by DRC checks to check for such
errors in a GDS file of unknown origin. The second version looks
for interactions between subcells that end up with intersections
of non-manhattan geometry landing on points that are not on the
database internal grid. Such errors cannot be seen by magic's DRC
engine by definition, and so must be detected while flattening
geometry for the DRC checks.
Tim Edwards