139 lines
5.5 KiB
HTML
139 lines
5.5 KiB
HTML
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H1 {color: black }
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<TITLE>Magic-7.3 Command Reference</TITLE>
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<BODY BACKGROUND=graphics/blpaper.gif>
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<H1> <IMG SRC=graphics/magic_title2.gif ALT="Magic VLSI Layout Tool Version 7.3">
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<IMG SRC=graphics/magic_OGL_sm.gif ALIGN="top" ALT="*"> </H1>
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<H2>lef</H2>
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<HR>
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LEF-format input and output
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<HR>
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<H3>Usage:</H3>
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<BLOCKQUOTE>
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<B>lef</B> <I>option</I> <BR><BR>
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<BLOCKQUOTE>
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where <I>option</I> may be one of the following:
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<DL>
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<DT> <B>read</B> [<I>filename</I>]
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<DD> Read a LEF file named <I>filename</I>[<B>.lef</B>]
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<DT> [<I>filename</I>] <B>-import</B>
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<DD> Read a LEF file. Import standard cells from <TT>.mag</TT>
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files
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<DT> <B>write</B> [<I>cell</I>]
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<DD> Write LEF for the current or indicated cell.
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<DT> <B>writeall</B>
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<DD> Write all cells including the top-level cell. This might
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be appropriate if the top-level cell is a compendium of
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standard cells.
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<DT> <B>writeall -notop</B>
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<DD> write all subcells of the top-level cell, but not the top-level
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cell itself. This is appropriate for generating a LEF library
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from a layout, for which the layout itself would be written to
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a DEF file.
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<DT> <B>help</B>
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<DD> Print help information
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</DL>
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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>lef</B> command writes LEF-format files, which are files
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containing technology information and information about the content
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of standard cells. It is used in conjunction with the <B>def</B>
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command to read databases of routed digital standard-cell layouts.
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The <TT>.lef</TT> file shares some information with the technology
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file in <B>magic</B>. At a minimum, to read <TT>.lef</TT> files
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from third-party sources, the technology file should have a
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<B>lef</B> section that maps magic layers to layer names that are
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found in the <TT>.lef</TT> and <TT>.def</TT> files. Without
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this information, <B>magic</B> will attempt to make an educated
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guess about the routing layers, which normally will be named
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in an obvious manner such as "metal1", "metal2", etc. The
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technology file section may be necessary to handle more complicated
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input such as obstruction layers. Most other aspects of a
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technology will be contained within the <TT>.lef</TT> file.
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When writing <TT>.lef</TT> files, <B>magic</B> will use internal
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layer names for the routing layers if no other information is
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present in the <B>lef</B> section of the technology file. <P>
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Because the <B>lef</B> format allows standard cells to be minimally
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defined (for purposes of protecting intellectual property), often
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the <TT>.lef</TT> file contains no actual layout information for
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the standard cells. <B>magic</B> provides a command option
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"<B>-import</B>". When specified, for each macro cell in the
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input <TT>.lef</TT> file, <B>magic</B> will look for a <TT>.mag</TT>
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file of the same name. If found, it will be loaded and used in
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preference to the definition in the <TT>lef</TT> file. <P>
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Magic uses the <B>port</B> mechanism for labels to determine
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what are the standard cells in a design. All cells containing
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<B>port</B> labels will be considered standard cells when writing
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a <TT>.lef</TT> file. Ports retain various bits of information
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used by the LEF/DEF definition, including the port use and
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direction. See the <B>port</B> documentation for more information.<P>
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Macro cell properties common to the LEF/DEF definition but that
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have no corresponding database interpretation in <B>magic</B>
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are retained using the cell <B>property</B> method in <B>magic</B>.
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There are specific property names associated with the LEF format.
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These are as follows:
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<DL>
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<DT> <B>LEFclass</B>
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<DD> Corresponds to the value of <B>CLASS</B> for a macro
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cell in the LEF format.
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<DT> <B>LEFsource</B>
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<DD> Corresponds to the value of <B>SOURCE</B> for a macro
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cell in the LEF format.
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<DT> <B>LEFsymmetry</B>
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<DD> Corresponds to the vlaue of <B>SYMMETRY</B> for a macro
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cell in the LEF format.
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</DL>
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Normally, when importing a LEF/DEF layout into <B>magic</B>, one
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will first execute a <B>lef read</B> command followed by a
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<B>def read</B> command. Likewise, when writing a layout, one
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will first execute a <B>lef writeall -notop</B> command followed
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by a <B>def write</B> command.
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</BLOCKQUOTE>
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<H3>Implementation Notes:</H3>
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<BLOCKQUOTE>
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<B>lef</B> is implemented as a built-in command in <B>magic</B>.
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Only the critical portion of the LEF syntax has been implemented.
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In particular, simulation-specific properties of the technology
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and of macro cells are not implemented.
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</BLOCKQUOTE>
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<H3>See Also:</H3>
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<BLOCKQUOTE>
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<A HREF=def.html><B>def</B></A> <BR>
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<A HREF=port.html><B>port</B></A> <BR>
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<A HREF=property.html><B>property</B></A> <BR>
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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> October 7, 2004 at 1:43am <P>
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</BODY>
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</HTML>
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