account for the fact that non-Manhattan tiles are processed twice
in the search, with the side mask bit 1 and 0 for each call. The
DRC check, like the Manhattan checks, only needs to check one of
these.
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.
DRC records contain an index into a string array instead of containing
a copy of a string. This is preliminary to changing the way the DRC
error plane is painted, so that the types painted will mark the error
type. This will (1) allow "drc why" to simply scan the DRC error
plane rather than running the DRC engine, (2) allow DRC errors to be
counted by area rather than by tile, and (3) let the DRC count be the
same whether done by "drc listall why" or "drc count".
(such as widespacing or directional surround) that will cause the
rule to be triggered without a cause due to a failure to reset the
error count from a previous triggered rule (the condition of failure
is much more rare than this explanation makes it sound, which is why
it went undiscovered for so long).
behaviors: (1) An additional syntax for "widespacing" that allows
both the triggering metal's width AND run-length, which is typical
of rules in 65nm-and-below processes; and (2) a new "option"
statement for the DRC section, with (for now) one possible flag
"wide-width-noninclusive", indicating that the metal width given
for "widespacing" rules means that a violation is only triggered
for material with a width greater than the given rule width (as
opposed to the default interpretation of a width greater than
or equal to the given rule width).
much larger area than necessary to the interaction check, and
the other which failed to scale the tech halo distance down
after scaling all the rules. Both of these led to huge areas
of a layout being unnecessarily checked when even a tiny part
of the layout was modified. Corrected behavior matches
expectations for interactive DRC response.
Tim Edwards