Crate libreda_db

This crate is a database for VLSI physical design. The core components are traits that define how netlist and layouts can be accessed and modified. Additionally the crate provides default implementations of those traits for representation of chip layouts and netlists.

Core parts

An important part of this crate are trait definitions that describe the access methods of cell hierarchies, netlists and layouts. The idea is that most algorithms should not be implemented for concrete types but for this traits. For instance an algorithm that analyzes a netlist without looking at the layout might be implemented for all types that implement the NetlistBase trait. In many cases this allows to be agnostic of the actual netlist implementation. Hence the algorithm implementation might be more portable.

A fundamental idea is that all things (cells, instances, pins, nets, shapes, etc.) have unique identifiers. The type of the identifiers is generically defined as an associated type of the traits. In practice the identifiers might be for example integers but they can also some sort of smart pointer.

The following are important traits which define how netlist and layouts can be accessed and modified:

• HierarchyBase - traverse cell hierarchies
• HierarchyEdit - edit cell hierarchies
• NetlistBase - traverse netlists
• NetlistEdit - edit netlists
• LayoutBase - access layout shapes
• LayoutEdit - edit layout shapes
• L2NBase - access the links between layout shapes and netlist
• L2NEdit - edit the links between layout shapes and netlists

Read more about netlists and layouts in the following modules:

• Netlist
• Layout

The Chip struct implements the above traits and hence can be used as a default data base structure.

Netlist/layout wrappers

Additional functionality can be added to netlists and layout structures with the following wrappers:

• Undo - Make modifications reversible
• FlatView - Create an on-the-fly flattened view of a hierarchical structure.

Input/output

Reading and writing data base structures is generally left to other crates such as libreda-oasis, libreda-lefdef, …

Geometric primitives

Two dimensional geometrical primitives (polygons, rectangles, etc.) are re-exported from the iron_shapes crate.

Technology-related data

There is no complete standard way to deal with technology related data. A proposal on how to also create an abstraction layer for technology data such as rules is here:

• technology - interfaces for accessing technology related information such commonly used DRC rules

Re-exports

• pub use iron_shapes;
• pub use iron_shapes_booleanop;

Modules

• chip
  Chip data structure holding netlist and layout together. Chip implements the L2NEdit trait and hence qualifies for representing netlists fused with a layout. Chip can also be used solely as a netlist structure or as a layout structure.
• derive
  Helpers for deriving trait implementations of core traits.
• flat_view
  Wrapper around a netlist which provides an on-the-fly flat view of a certain cell. The presented view is flattened until leaf cells. Internally this works by using component IDs that are actually paths through the hierarchy.
• hierarchy
  Concept of ‘hierarchy’ which is used in layouts and netlists.
• index
  Data structure for creating indices related to some other type. This is used to create handles for data stored in hash maps.
• l2n
  Trait definitions for layouts fused with netlists.
• layout
  Geometrical layout data structures.
• netlist
  Traits for representation of circuit-level netlists.
• prelude
  The prelude helps to import most commonly used modules.
• profile
  Acquire performance metrics of single data-base functions.
• property_storage
  Container structs for user defined properties.
• rc_string
  RcString is a simple data structure for the representation of strings. In contrast to String, RcString can be efficiently cloned. It is intended to be used in cases where objects are indexed by a human readable name.
• reference_access
  Experimental
• region_search
  Add fast region queries to layouts.
• rw_reference_access
  Experimental
• technology
  Traits and datastructures for the representation of technology related properties, especially design rules.
• traits
  Re-export all traits defined in this crate.
• undo
  Experimental: Wrapper around netlist, layout and L2N structures that allows undoing of operations.