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