snarled README

Layout connectivity checker.

snarled is a python package for checking electrical connectivity in multi-layer layouts.

It is intended to be "poor-man's LVS" (layout-versus-schematic), for when poverty has deprived the man of both a schematic and a better connectivity tool.

• Source repository
• PyPI
• Github mirror

Installation

Requirements:

• python >= 3.10 (written and tested with 3.11)
• numpy
• klayout (python package only)

Install with pip:

pip install snarled

Alternatively, install from git

pip install git+https://mpxd.net/code/jan/snarled.git@release

Example

See examples/check.py (python interface) or examples/run.sh (command-line interface).

Command line:

snarled connectivity.oas connectivity.txt -m layermap.txt

Python interface:

from pprint import pformat
import logging

import snarled
from snarled.types import layer_t


logging.basicConfig()
logging.getLogger('snarled').setLevel(logging.INFO)


connectivity = [
    ((1, 0), (1, 2), (2, 0)),   # M1 to M2 (via V12)
    ((1, 0), (1, 3), (3, 0)),   # M1 to M3 (via V13)
    ((2, 0), (2, 3), (3, 0)),   # M2 to M3 (via V23)
    ]

labels_map: dict[layer_t, layer_t] = {
    (1, 0): (1, 0),
    (2, 0): (2, 0),
    (3, 0): (3, 0),
    }

filename = 'connectivity.oas'

nets = snarled.trace_layout(filename, connectivity, topcell='top', labels_map=labels_map)
result = snarled.TraceAnalysis(nets)

print('\n')
print(result)

this prints the following:

INFO:snarled.trace:Adding layer (3, 0)
INFO:snarled.trace:Adding layer (2, 3)
INFO:snarled.trace:Adding layer (1, 3)
INFO:snarled.trace:Adding layer (1, 2)
INFO:snarled.trace:Adding layer (1, 0)
INFO:snarled.trace:Adding layer (2, 0)


Trace analysis
=============
Nets
(groups of electrically connected labels)
        SignalA,SignalB
        SignalC,SignalD,SignalI
        SignalE,SignalF
        SignalG,SignalH
        SignalK
        SignalK
        SignalL

Opens
(2+ nets containing the same name)
        SignalK : 2 nets

Shorts
(2+ unique names for the same net)
        SignalA,SignalB
        SignalC,SignalD,SignalI
        SignalE,SignalF
        SignalG,SignalH
=============

Code organization

• The primary functionality is in trace; specifically trace.trace_layout().
• main provides a command-line interface, supported by the functions in utils.