74 lines
2.4 KiB
C++
74 lines
2.4 KiB
C++
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/*
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* Copyright (c) 1998 Stephen Williams (steve@picturel.com)
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*
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* This source code is free software; you can redistribute it
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* and/or modify it in source code form under the terms of the GNU
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* General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#if !defined(WINNT)
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#ident "$Id: nobufz.cc,v 1.1 1998/12/02 04:37:13 steve Exp $"
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#endif
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/* NOBUFZ Function
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* This function transforms the netlist by removing BUFZ nodes that
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* have no obvious effect. The assumption here is that the BUFZ node
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* transmits information perfectly in one direction, and not at all in
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* the other.
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*
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* A BUFZ will *not* be eliminated if the output link is connected to
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* other outputs. The BUFZ protects its input link from the
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* double-driving on its output, so the bufz is not meaningless and
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* cannot be removed.
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*/
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# include "netlist.h"
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# include <assert.h>
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static bool is_a_bufz_node(const NetNode*obj)
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{
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return dynamic_cast<const NetBUFZ*>(obj);
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}
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void nobufz(Design*des)
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{
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des->clear_node_marks();
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while (NetNode*obj = des->find_node(&is_a_bufz_node)) {
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NetBUFZ*cur = dynamic_cast<NetBUFZ*>(obj);
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assert(cur);
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/* If there are more output pins on the output size of
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the BUFZ, then the BUFZ has a real effect (it
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protects its input side) and cannot be eliminated. */
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if (count_outputs(cur->pin(0)) == 1) {
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connect(cur->pin(0), cur->pin(1));
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delete cur;
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} else {
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cur->set_mark();
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}
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}
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}
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/*
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* $Log: nobufz.cc,v $
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* Revision 1.1 1998/12/02 04:37:13 steve
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* Add the nobufz function to eliminate bufz objects,
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* Object links are marked with direction,
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* constant propagation is more careful will wide links,
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* Signal folding is aware of attributes, and
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* the XNF target can dump UDP objects based on LCA
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* attributes.
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*
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*/
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