GDSII Stream format is the standard file format for transfering/archiving 2D graphical design data. It contains a hiearchy of structures, each structure containing. Beyond that, let me say that the stream format is quite simple. I suspect that the people at Calma put a lot of thought into creating a file that. Learn files and view a list of programs that open them.
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This record must be present if there are any reference libraries bound to the current library. The second is the size of a database unit in meters. The third point locates a position which is displaced from the reference point by the inter-row spacing times the number of rows.
SPIE Handbook of Microlithography, Micromachining and Microfabrication
Therefore, text elements may look different with other viewers and fornat often ignored in mask production. The third and fourth bytes contain the nunber of rows. The sixth data type is the “Eight Byte Real”. The formula below uses the unsigned integer value of these 7 bytes as the numerator of a fraction.
A node may have from 1 to 50 pairs of coordinates. I suspect that they did this due to the modest computers that they had to work with. MAG [1B05] Eight-byte real: In stream files created by non-Calma programs, this should be missing or all field should be 0.
An AREF has exactly three pairs of coordinates, which specify the orthogonal array lattice. The reference library names may include directory specifiers separated with “: The LayoutEditor can store layer names by a non-standard extension see below.
The first two bytes of the record header contain a count in eight-bit bytes of the total record length. If a polygon exceeds this limit, it will be split into two or more polygons when saving the file.
This marks the beginning of an array reference element an array of cells. This marks the end of a structure.
B.2 Calma GDS II stream format (GDSII)
This enables fast performance and avoids any unecessary conversion. This appendix omits the description of tape formatting, since disk files and disk file images on tape and other media are now the norm . Webarchive template wayback links. Starts with name of the first library and is followed by the second. The code is 0x The name for the first reference library starts at byte 0 and the name of the second library starts at byte 45 decimal.
They sure did that with the layer numbers and data types. From Wikipedia, the free encyclopedia.
Speaking of dated, Stream Format allows records to be written out to multiple reels of tape. Cells can be nested with no fprmat as to how deep the nesting goes though I have yet to see nesting more than 9 levels deep.
Despite its limited set of features and low data density, it became the industry conventional format for transfer of IC layout data between design tools of different vendors, all of which operated with proprietary data formats.
SPIE Handbook, Volume 1: Microlithography, Section
If omitted, zero is assumed. A floating point number is made up of three parts: For every hex digit shifted, the exponent is decreased by one. Attribute numbers and are reserved for the user integer and user string properties, which existed prior to Release 3.
One or more Stream records 3. Save Path as Polygon Path elements with a width greater than 0 will be saved as a polygon. Exactly 3 pairs 1: Maximum length is characters.
Bit 14 flags absolute angle. Real numbers are not represented in IEEE format. Order the complete book from SPIE. A string giving ranges of layers and datatypes separated by a semicolon. The data can be used to reconstruct all or part of the artwork to be used in sharing layouts, gdaii artwork between different tools, or creating photomasks.
There is a section below with hexadecimal values of the various record types and a brief gdsui of the types. While other formats have been proposed to replace it and one, OASIS, seems to be gaining some traction GDSII remains by far the main way of describing the physical layout for the masks used to build a chip.
Grsii elements are further defined in the Stream syntax list. Exactly 1 pair AREF: However it is possible to save such large polygon in multiple blocks. Objects contained in a GDSII file are grouped by assigning numeric attributes to them including a “layer number”, “datatype” or “texttype”. This is another artifact of the 16 bit words that the stream file format assumes. The first is the number of columns.
This marks the beginning of a path element. Byte swapping is required when reading or writing integers with a little-endian machine, such as a VAX. The more significant bytes appear first in the file, so that by default no byte swapping is required when reading the integers with a big-endian CPU e. This is done by adding an additional cell to the design with the name Gdeii that contains a text elements on tile layer with the layer names.
The second is called a “Bit array”. This information is used only when reading the data into a new library.
Binary The database is binary for compactness.