coriolis/documentation/deprecated/lefapi/lefapi.rst

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.. -*- Mode: rst -*-
.. include:: ../etc/definitions.rst
=================
LEF API Reference
=================
The LEF API reference is copyrighted by |Cadence| (http://www.cadence.com)
under the `Apache License, Version 2.0`_ and is available here:
`LEF API <../../lefdef/lefapi/ch1Intro.html>`_
Implementation Notes
====================
Understanding Units
~~~~~~~~~~~~~~~~~~~
In the ``UNITS`` section, the statement: ::
DATABASE MICRONS LEFconvertFactor
Means that:
#. The distances in the |LEF| file are expresseds (always, it seems) in
micrometers.
#. The distances are multiples of :math:`\frac{1}{LEFconvertFactor}` which is
the smallest amount of distance we can represent. By default ``LEFconvertFactor``
is set to ``100``, which means steps of ``0.01µm``.
This is the equivalent of the **precision** factor in the |Hurricane| database.
Callback Calling Order
~~~~~~~~~~~~~~~~~~~~~~
The callback for the ``PIN`` section is called *before* the callback of the whole
``MACRO`` it belongs to.
As a consequence, we have to create ``Net`` before the ``Cell`` can be known.
To avoid transient storage of lots of informations while we are reading the
``PIN``, when we encounter one **and** no temporary ``Cell`` exists, we
create one named ``"LEFImportTmpCell"``. This temporary ``Cell`` will be renamed
and configured when the subsequent ``MACRO`` callback is called.