tech file to correct the underlying problem with the SkyWater
sky130 process in which a different layer/purpose pair is used
for TEXTTYPE and DATATYPE for the same layer. Previously, all
output from magic writes the same pair for both when writing a
port label. The new method preserves existing syntax, although
there are some differences based on what order the "port"
statement appears relative to other types for the same layer.
due to a missing function prototype. Modified the GDS output
flow to always output instance IDs as a property, not just in the
non-default case. The property has been used for many years and
appears to be accepted by all tools reading GDS, so there is no
downside to always generating this output. This has the upside
that default instance names don't get scrambled by going from
magic to GDS and back to magic.
for the squares-grid operator and for GDS compression. But I
reverted the "calma contact" option to be false by default, because
the method does not exactly match the output when not using cell
instance arrays, and so may produce unexpected results. Will
need a different implementation that uses the same code to generate
the same (effective) layout.
default behavior of magic to make use of the "gds contacts true"
option to output contacts as arrays of subcells instead of
individual boundary entries, as the former is much more efficient
than the latter. Set the option to be true by default, and set
the "gds flatglob" option to have one entry "$$*$$" corresponding
to the contact subcells created by the "gds contacts" option, so
that GDS reads and writes as it did previously (but using a
different method). Expanded the method to include "squares-grid"
and "slots" operators (the latter should produce much more
efficient fill pattern arrays). Implemented for both compressed
and uncompressed GDS. Tested in all variations.
attempt is made to write an abstract view to GDS. This behavior can
be overridded with the new command option "gds abstract [enable|disable]".
Also: Corrected extraction to allow split tiles to be set as the
reference tile for a node. Previously this was allowed only if the
tile was the first to be searched, but that can cause different tiles to
be marked as the reference depending on where the search starts,
resulting in different names for the same node in .ext files, which is
bad. Also: Modified the LEF annotation to avoid bad entries in the LEF
that would create layers in the layout where none exist.
This commit makes the code (mostly) C99-compatible, enabling to compile
it without the -Wno-error=implicit-function-declaration flag. This
way, Magic becomes usable on arm64 architectures, specifically on Apple
computers with M1/M2 SoC.
calculation of the area to check for output and the clip box
does not reduce the size of any layer associated with the
fixed bounding box declared by the FIXED_BBOX property.
polygon cell has been created with the "gds polygon subcell"
option and the parent cell is read-only (vendor GDS), then the
polygon cell does not actually exist in the original GDS and
should not be output during a "gds write".
Compression levels of the output can be controlled with the "gds
compress [<value>]" command, where <value> 0 (default) is uncompressed
output, 6 is "normal" gzip compression, and 9 is maximum compression.
pointing GDS_FILE to a compressed filename when using "gds readonly
true" on a compressed file. The start and end pointers still point
to data bounds in the uncompressed file.
of systems calls to "gzip" and "gunzip". A compressed GDS file can
be made simply by doing "gds write <name>.gds.gz", and can be read
simply by doing "gds read <name>.gds.gz". Names of compressed files
can be put in the GDS_FILE property of a cell.
"gds datestamp <value>" as an option to force a specific datestamp
on the GDS output. This is a third option beyond the previous two
which were either to use the current time or to write zero. The
new option allows an entire library to get a common timestamp, for
example, related to a PDK version number. The "gds nodatestamp"
option has been retained for backwards compatibility.
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.
it is easy to subvert the process by updating GDS without updating
the pointers, it is trivial to end up with bad GDS output. The
sanity checks confirm that the position pointed to is a complete
structure (check begin and end records), and that it has the same
name as the cell (this is not a requirement, as there are reasons
one might want to point to data from a structure of a different
name, but a warning will be printed).
cell is referenced by a GDS "addendum" file but is not in either
the tree of the root def or any other dumped GDS file, then check
the database for those files and output them if they exist. This
allows one way to get around missing cells in the GDS output if a
cell from a GDS addendum is used but no cells from the library
that the file is an addendum of are used.
introduced: The use of substitutions for PDKPATH and home directory
in path names for GDS files referenced in abstract views, and the
"gds addendum" option. Both were interfering with magic's handling
of writing GDS files from abstract layout views.
from 98 (arbitrarily selected) to 61 (apparently commonly used by
other tools). This should help increase compatibility with GDS
files output from other tools.
worded warning if an abstract cell view is written to GDS.
Corrected the "cellname ... writeable" command to allow an
overrride of the read-only status of a cell. That change had
been made before but apparently got reverted by the recent
rollback.
cell def that is marked for a "full dump" from a referenced GDS
file. This change was supposed to have been done a few commits
ago but did not work as advertised.
magic database derived layout of a cell that declares GDS_FILE
but for which the GDS file referenced cannot be found or read.
This will produce an incomplete GDS file instead of an apparently
good and complete GDS file that actually contains bad data. Also:
Added new command "random" that allows a random seed to be set,
for use with the GDS output when writing a full dump of a GDS
file. Otherwise, the output prefixes are always the same, which
defeats the purpose of adding the random prefix.
to stop the search whenever a cell is not found. Used this to implement
a new option for GDS writes, "gds undefined allow|disallow" (default
"disallow") controls whether or not GDS with undefined references will
be allowed to be written. Similarly affects CIF and LEF writes, extraction,
and DRC (when running "drc check" from the top).
"gds write" command, since "Writing cell" is easily confused with
writing a .mag database file. "Generating output" seems clearer
to me. Maybe it's just me.
true, this will force the "gds write" command to write out creation
date stamps as zero. This is very useful for avoiding changing the
contents of an otherwise-unchanged layout, especially if it is in
a git repository where it will force the entire file to be replaced.
hierarchical processing from CIFGenSubcells() and CIFGenArrays(), and to
avoid certain operators that are useless and harmful when applied
hierarchically; namely squares, slots, bbox, boundary, and net.
templayers. This permits some useful interactions like growing to
the size of a bounding box, or abutment box, as well as many other
possibilities. Also: Corrected the use of "cif see" for the boundary
(abutment box) layer, which was not working because the "cif see"
command uses a flattened CellDef that does not have the boundary
property of the cell it was flattened from.
GDS of abstract views, such that if the cellname being dumped is the
same as the library name, then no prefix is added to subcells. This
behavior may be changed in the future.
only at the time of running the command "load". But cells are generally
loaded only on an as-needed basis, so the dereferencing option must be
saved as a flag in the cell and honored whenever its subcells are expanded
or otherwise read at a later time.
limit of the Calma definition, and probably has not done so for ages.
Nobody informed me of this. The restriction has been lifted from
GDS input and output in Magic. It can be reinstated if necessary by
setting a flag in the cifoutput section of the techfile, but it is
likely that this will not be necessary unless there are other tools
that enforce the limit and will not read a GDS file that exceeds it.
rid of redundant port entries in subcircuits. There is still an outstanding
issue as to whether nodes and connections need to be recursively iterated
to the hierarchy bottom. The current fix corrected the test case. Also,
added a "-dereference" option to the "load" command to revert to the
original behavior of using only search paths from "addpath" when searching
for files to load.
the forward-referenced GDS cell problem) in which when writing cells
from 3rd-party GDS, the structure names are written to GDS with the
indicator flag in front, making the structure names and the referenced
names different, so that the GDS file is no longer valid. This has
been fixed.
files that have forward references (cells that are instanced before
they are defined), resulting in those cells being given an undefined
string for a prefix, which will result in corrupted GDS output.
Also added a method to prevent forward-referenced cells from triggering
a "redundantly defined" error message when the structure is output.
the compiler. Some are obscure functions (plot verstatec hasn't
been used in years) but others (like SPICE distributed junctions)
are potentially significant sources of unexpected crashes on
systems that don't zero uninitialized memory.
Tim Edwards
Alessandro De Laurenzis