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Gds21 Integrated Circuit Layout Parser & Writer
GDSII is the IC industry’s de facto standard for storing and sharing layout data. Gds21 is a library for reading and creating GDSII data, similar to and largely inspired by libraries such as gdstk and its predecessor gdspy. Gds21 differs in being designed primarily as an interface layer to GDSII for the larger Layout21 library. Reading and generating GDSII-format data are primary goals; offering ease-of-use functionality for more elaborate manipulations of GDS data is not. (Although these manipulations can be performed on Gds21’s data structures). Gds21 accordingly stores layout data on GDSII’s terms, using GDSII’s idioms, naming conventions, and datatypes.
Layout data is represented in three primary forms:
- A short tree with three layers:
- The root is a
GdsLibrary
, which primarily consists of a set of cells (GdsStruct
s), and secondarily a set of metadata. EachGdsLibrary
is a universe unto itself, in that it has no mechanisms for comprehending layout cells or data defined outside itself. On-disk eachGdsLibrary
is typically paired one-to-one with a.gds
file. - Libraries consist of cell definitions AKA
GdsStruct
s, which define each layout cell (or module, or “struct” in GDSII terms). - Cells consist of
GdsElement
s, an enumeration which includes individual polygons (GdsBoundary
), instances of other layout cells (GdsStructRef
), text (GdsTextElem
), and a few other geometric elements.
- The root is a
- For storage on disk, the
GdsLibrary
tree is flattened to a series ofGdsRecord
s. These records indicate the beginning, end, and content of each tree-node. Detailed descriptions of these records comprise the majority of the GDSII spec. - Records are stored on-disk in binary form as detailed in the GDSII spec.
Each includes a record-type header, datatype, length field, and optional additional content.
These raw-bytes are never stored by Gds21, only generated and consumed on their way into and out of
Read
andWrite
objects (typicallyFile
s).
Usage
Loading a GdsLibrary
from disk:
let lib = GdsLibrary::load("sample.gds")?;
Creating a new and empty GdsLibrary
, and adding a GdsStruct
cell-definition:
use gds21::{GdsLibrary, GdsStruct};
let mut lib = GdsLibrary::new("mylib");
lib.structs.push(GdsStruct::new("mycell"));
Saving a GdsLibrary
to disk:
lib.save("mylib.gds");
Serialization
Each element in Gds21’s GdsLibrary
tree is serde
-serializable.
GDSII data can be straightforwardly serialized in any serde-supported format.
Examples:
let lib = gds21::GdsLibrary::new("mylib");
let json = serde_json::to_string(&lib);
let yaml = serde_yaml::to_string(&lib);
let toml = toml::to_string(&lib);
Gds21 includes built-in support for a subset of serde-formats via its SerializationFormat
enumeration,
and support for directly reading and writing files in each format via its accompanying SerdeFile
trait.
Example using SerializationFormat::Yaml
:
use gds21::SerializationFormat::Yaml;
let lib = gds21::GdsLibrary::new("mylib");
// Write to YAML-format file
Yaml.save(&lib, "mylib.gds.yaml")?;
// And read back from file
let lib2: gds21::GdsLibrary = Yaml.open("mylib.gds.yaml")?;
Note these text-based representations will generally be substantially larger than binary GDSII data.
Structs
Gds Array Reference
Gds Boundary Element
Gds Box Element
Gds Modification Dates & Times
Gds Element Flags
GDSII’s Home-Grown Floating-Point Format
Gds Layer Spec
Gds Library
Gds Node Element
Gds Path Element
Gds Plex
Gds Spatial Point
Gds Text-Presentation Flags
Gds Property
Gds Record Header
Gds Summary Stats
Gds Translation Settings
Gds Struct (Cell) Definition
Gds Struct Reference (Cell Instance)
Gds Text Element
Gds Library Units
Unsupported (But Spec-Valid) Features
Enums
Enumeration of each context in which a record can be parsed, primarily for error reporting
Gds DataType Enumeration
Gds Element Enumeration
Gds Error Enumeration
Gds Mask-Format Enumeration
Gds Record Enumeration
Gds Record Types
Enumerated, Supported Serialization Formats
Traits
Type Definitions
GdsResult Type-Alias