inire/README.md

# inire: Auto-Routing for Photonic and RF Integrated Circuits

`inire` is a high-performance auto-router designed specifically for the physical constraints of photonic and RF integrated circuits. It utilizes a Hybrid State-Lattice A* search combined with "Negotiated Congestion" (PathFinder) to route multiple nets while maintaining strict geometric fidelity and clearance.

## Key Features

*   **Hybrid State-Lattice Search**: Routes using discrete 90° bends and parametric S-bends, ensuring manufacturing-stable paths.
*   **Negotiated Congestion**: Iteratively resolves multi-net bottlenecks by inflating costs in high-traffic regions.
*   **Analytic Correctness**: Every move is verified against an R-Tree spatial index of obstacles and other paths.
*   **1nm Precision**: All coordinates and ports are snapped to a 1nm manufacturing grid.
*   **Safety & Proximity**: Incorporates a "Danger Map" (pre-computed distance transform) to maintain optimal spacing and reduce crosstalk.
*   **Locked Paths**: Supports treating existing geometries as fixed obstacles for incremental routing sessions.

## Installation

`inire` requires Python 3.11+. You can install the dependencies using `uv` (recommended) or `pip`:

```bash
# Using uv
uv sync

# Using pip
pip install numpy scipy shapely rtree matplotlib
```

## Quick Start

```python
from inire.geometry.primitives import Port
from inire.geometry.collision import CollisionEngine
from inire.router.danger_map import DangerMap
from inire.router.cost import CostEvaluator
from inire.router.astar import AStarContext
from inire.router.pathfinder import PathFinder

# 1. Setup Environment
engine = CollisionEngine(clearance=2.0)
danger_map = DangerMap(bounds=(0, 0, 1000, 1000))
danger_map.precompute([]) # Add polygons here for obstacles

# 2. Configure Router
evaluator = CostEvaluator(
    collision_engine=engine, 
    danger_map=danger_map,
    greedy_h_weight=1.2
)
context = AStarContext(
    cost_evaluator=evaluator,
    bend_penalty=10.0
)
pf = PathFinder(context)

# 3. Define Netlist
netlist = {
    "net1": (Port(0, 0, 0), Port(100, 50, 0)),
}

# 4. Route
results = pf.route_all(netlist, {"net1": 2.0})

if results["net1"].is_valid:
    print("Successfully routed net1!")
```

## Usage Examples

For detailed visual demonstrations and architectural deep-dives, see the **[Examples README](examples/README.md)**.

Check the `examples/` directory for ready-to-run scripts. To run an example:
```bash
python3 examples/01_simple_route.py
```

## Documentation

Full documentation for all user-tunable parameters, cost functions, and collision models can be found in **[DOCS.md](DOCS.md)**.

## Architecture

`inire` operates on a **State-Lattice** defined by $(x, y, \theta)$. From any state, the router expands via three primary "Move" types:
1.  **Straights**: Variable-length segments.
2.  **90° Bends**: Fixed-radius PDK cells.
3.  **Parametric S-Bends**: Procedural arcs for bridging small lateral offsets ($O < 2R$).

For multi-net problems, the **PathFinder** loop handles rip-up and reroute logic, ensuring that paths find the globally optimal configuration without crossings.

## Configuration

`inire` is highly tunable. Every major component (Router, CostEvaluator, PathFinder) accepts explicit named arguments in its constructor to control expansion rules, cost weights, and convergence limits. See `DOCS.md` for a full parameter reference.

## License

This project is licensed under the GNU Affero General Public License v3. See `LICENSE.md` for details.