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<TITLE>Magic-7.3 Command Reference</TITLE>
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<H1> <IMG SRC=graphics/magic_title2.gif ALT="Magic VLSI Layout Tool Version 7.3">
<IMG SRC=graphics/magic_OGL_sm.gif ALIGN="top" ALT="*"> </H1>
<H2>cellsearch</H2>
<HR>
Execute a TCL procedure on each cell definition or instance in the hierarchy
<HR>
<H3>Usage:</H3>
<BLOCKQUOTE>
<B>cellsearch</B> [<B>instances</B>] <I>procedure</I> <BR><BR>
<BLOCKQUOTE>
where <I>procedure</I> is the name of a predefined Tcl procedure
(see Summary, below).
</BLOCKQUOTE>
</BLOCKQUOTE>
<H3>Summary:</H3>
<BLOCKQUOTE>
The <B>cellsearch</B> command is a method for user access to
the <B>magic</B> database search routines. It searches the
hierarchical database for all cell definitions and applies
the callback procedure to each. If the <B>instances</B>
keyword is present, it searches the database for all cell
instances and applies the callback procedure to each. The
callback procedure must be defined as described below.
Note that the callback method into Tcl is inherently slow
and should only be used for non-compute-intensive tasks. <P>
The Tcl callback procedure for the <B>instances</B> version of
the <B>cellsearch</B> command is passed six values, the bounding
box coordinates of the instance, the instance use name (id), and
the name of the parent cell definition. The procedure must be
defined to accept these six arguments, as in the following
example:
<BLOCKQUOTE> <TT> <PRE>
proc inst_callback {llx lly urx ury usename defname} {
puts stdout "Instance $usename of $defname bbox $llx $lly $urx $ury"
}
</PRE> </TT> </BLOCKQUOTE>
The Tcl callback procedure for the cell definition search
is passed one value, the name of the cell definition. The
procedure must be defined to accept this single argument, as
in the following example:
<BLOCKQUOTE> <TT> <PRE>
proc def_callback {defname} {
puts stdout "Cell $defname"
}
</PRE> </TT> </BLOCKQUOTE>
</BLOCKQUOTE>
<H3>Implementation Notes:</H3>
<BLOCKQUOTE>
<B>cellsearch</B> is implemented as an internal <B>magic</B>
command that links to an external Tcl procedure as a callback
function. This routine is experimental and subject to change
without notice.
</BLOCKQUOTE>
<H3>Bugs:</H3>
<BLOCKQUOTE>
As currently implemented, there is no protection against
calling a <B>magic</B> command from the callback procedure
that will alter the internal cell hash table while it is
being traversed, causing a crash. The implementation
should be changed to a 2-step procedure that traverses the
cell hash table first, creating an internal list of function
arguments to pass for each cell, and then executes the
callback function on each. <P>
There are more efficient ways of executing the callback
function than Tcl_EvalEx(). In particular, the procedure
should be cast as a Tcl object and Tcl_EvalObjEx() used.<P>
The callback function should allow in-line Tcl procedures
and use the standard Tcl/Tk method of "%" escape sequences
used as arguments to the callback function that allow the
user to specify what arguments are passed to the callback
function (as is done for the <B>tag</B> command).
</BLOCKQUOTE>
<H3>See Also:</H3>
<BLOCKQUOTE>
<A HREF=search.html><B>search</B></A> <BR>
</BLOCKQUOTE>
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<TD> <A HREF=commands.html>Return to command index</A>
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<P><I>Last updated:</I> October 4, 2004 at 5:05am <P>
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