118 lines
4.4 KiB
HTML
118 lines
4.4 KiB
HTML
<HTML>
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<STYLE type="text/css">
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H1 {color: black }
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H2 {color: maroon }
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H3 {color: #007090 }
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</STYLE>
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</HEAD>
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<TITLE>Magic-8.3 Command Reference</TITLE>
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<BODY BACKGROUND=graphics/blpaper.gif>
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<H1> <IMG SRC=graphics/magic_title8_3.png ALT="Magic VLSI Layout Tool Version 8.3">
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<IMG SRC=graphics/magic_OGL_sm.gif ALIGN="top" ALT="*"> </H1>
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<H2>xor</H2>
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<HR>
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Perform exclusive-or between the current cell and the indicated destination cell.
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The destination cell is overwritten with the result.
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<HR>
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<H3>Usage:</H3>
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<BLOCKQUOTE>
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<B>xor</B> [<I>option</I>] <I>cellname</I> <BR><BR>
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<BLOCKQUOTE>
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where <I>cellname</I> is the name of a cell definition to be
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compared against, and into which the compared geometry will be placed.
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<I>option</I> may be one of <B>-nolabels</B>, <B>-nosubcircuit</B>,
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or <B>-novendor</B>, similar to the "<B>flatten</B>" command.
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</BLOCKQUOTE>
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</BLOCKQUOTE>
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<H3>Summary:</H3>
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<BLOCKQUOTE>
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The <B>xor</B> command compares the current edit cell against
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the target cell <I>cellname</I> by flattening and exclusive-or,
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replacing the target cell paint as it works. The result is an
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empty cell if the two cells have exactly the same geometry;
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otherwise, paint remains in the target cell where the geometry
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of the current edit cell does not match the geometry of the
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target cell.
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<P>
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The target cell is assumed to be flattened already. That is,
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to compare hierarchical layout <I>layout1</I> to hierarchical
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layout <I>layout2</I>, one would normally do:
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<BLOCKQUOTE>
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<TT>load <I>layout1</I></TT><BR>
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<TT>flatten <I>dest</I></TT><BR>
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<TT>load <I>layout2</I></TT><BR>
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<TT>xor <I>dest</I></TT><BR>
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</BLOCKQUOTE>
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This will result in cell <I>dest</I> containing geometry
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mismatches between cell <I>layout1</I> and cell <I>layout2</I>. <P>
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The options allow selective flattening, as follows:
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<DL>
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<DT> <B>-nolabels</B>
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<DD> Prevents magic from copying labels into the flattened cell.
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Otherwise, magic flattens labels by prepending the cell
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hierarchy to each label as it copies it into the flat cell.
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<DT> <B>-nosubcircuit</B>
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<DD> Prevents magic from flattening cells declared to be subcircuits
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(by the presence of ports in the cell). These cells are
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retained as subcells in the flattened version.
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<DT> <B>-novendor</B>
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<DD> Prevents magic from flattening cells that are vendor cells,
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that is, cells that are generated by reading GDS using the
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<B>gds readonly</B> option, or which have the appropriate
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property values set.
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</DL>
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In effect, <B>xor</B> is just the command <B>flatten</B> called
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with a special paint translation table that erases paint in the
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target when painted with the same type from the source. <P>
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Note that <I>cellname</I> is a top-level cell but is not displayed
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or saved subsequent to the <B>xor</B> command. The usual
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procedure is to follow the command "<B>xor</B> <I>cellname</I>"
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with "<B>load</B> <I>cellname</I>", to view the new compared
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layout. <P>
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Also note that a technology file's paint and erase tables
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can interfere with strict XOR function results. Typical paint
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and erase rules will tend to generate a result that is useful
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for a yes-no answer (cells either match or not), and for finding
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places in mismatched cells where differences occur. But it may
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not be possible to determine exactly what the difference is
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from the <B>xor</B> output. For a "proper" XOR function, use
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a techfile that does not have interacting types and planes, and
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draws contact cuts on separate planes rather than using magic's
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contact types (which automatically have interacting paint and
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erase rules).
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</BLOCKQUOTE>
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<H3>Implementation Notes:</H3>
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<BLOCKQUOTE>
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<B>xor</B> is implemented as a built-in command in <B>magic</B>,
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available from magic version 8.1.64.
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</BLOCKQUOTE>
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<P><IMG SRC=graphics/line1.gif><P>
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<TABLE BORDER=0>
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<TR>
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<TD> <A HREF=commands.html>Return to command index</A>
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</TR>
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</TABLE>
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<P><I>Last updated:</I> March 7, 2020 at 1:06pm <P>
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</BODY>
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</HTML>
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