Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

121 lines (102 sloc) 3.367 kb
/*
* Copyright (c) 2000 Stephen Williams (steve@icarus.com)
*
* This source code is free software; you can redistribute it
* and/or modify it in source code form under the terms of the GNU
* General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT) && !defined(macintosh)
#ident "$Id: link_const.cc,v 1.5 2000/07/14 06:12:57 steve Exp $"
#endif
# include "netlist.h"
# include "netmisc.h"
bool link_drivers_constant(const Link&lnk)
{
const Nexus*nex = lnk.nexus();
for (const Link*cur = nex->first_nlink()
; cur ; cur = cur->next_nlink()) {
if (cur == &lnk)
continue;
if (cur->get_dir() == Link::INPUT)
continue;
/* If the link is PASSIVE then it doesn't count as a
driver if its initial value is Vz. This is pertinant
because REGs are PASSIVE but can receive values from
procedural assignments. */
if ((cur->get_dir() == Link::PASSIVE)
&& (cur->get_init() == verinum::Vz))
continue;
if (! dynamic_cast<const NetConst*>(cur->get_obj()))
return false;
}
return true;
}
verinum::V driven_value(const Link&lnk)
{
const Nexus*nex = lnk.nexus();
for (const Link*cur = nex->first_nlink()
; cur ; cur = cur->next_nlink()) {
const NetConst*obj;
if (obj = dynamic_cast<const NetConst*>(cur->get_obj()))
return obj->value(cur->get_pin());
}
return lnk.get_init();
}
NetConst* link_const_value(Link&pin, unsigned&idx)
{
NetConst*robj = 0;
unsigned ridx = 0;
Nexus*nex = pin.nexus();
for (Link*cur = nex->first_nlink()
; cur ; cur = cur->next_nlink()) {
NetConst*tmp;
if ((tmp = dynamic_cast<NetConst*>(cur->get_obj())) == 0)
continue;
if (robj != 0)
continue;
robj = tmp;
ridx = cur->get_pin();
}
idx = ridx;
return robj;
}
/*
* $Log: link_const.cc,v $
* Revision 1.5 2000/07/14 06:12:57 steve
* Move inital value handling from NetNet to Nexus
* objects. This allows better propogation of inital
* values.
*
* Clean up constant propagation a bit to account
* for regs that are not really values.
*
* Revision 1.4 2000/06/25 19:59:42 steve
* Redesign Links to include the Nexus class that
* carries properties of the connected set of links.
*
* Revision 1.3 2000/05/14 17:55:04 steve
* Support initialization of FF Q value.
*
* Revision 1.2 2000/05/07 04:37:56 steve
* Carry strength values from Verilog source to the
* pform and netlist for gates.
*
* Change vvm constants to use the driver_t to drive
* a constant value. This works better if there are
* multiple drivers on a signal.
*
* Revision 1.1 2000/04/20 00:28:03 steve
* Catch some simple identity compareoptimizations.
*
*/
Jump to Line
Something went wrong with that request. Please try again.