125 lines
3.1 KiB
C++
125 lines
3.1 KiB
C++
/*
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* Copyright (c) 1998-2000 Stephen Williams (steve@icarus.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) && !defined(macintosh)
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#ident "$Id: vvm_bit.cc,v 1.13 2001/01/16 02:44:18 steve Exp $"
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#endif
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# include "vvm.h"
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bool negedge(vpip_bit_t from, vpip_bit_t to)
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{
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if (B_IS0(from))
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return false;
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if (B_ISX(from) || B_ISZ(from))
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return B_IS0(to);
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if (B_IS1(from))
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return ! B_IS1(to);
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return false;
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}
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bool posedge(vpip_bit_t from, vpip_bit_t to)
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{
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if (B_IS1(from))
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return false;
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if (B_ISX(from) || B_ISZ(from))
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return B_IS1(to);
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if (B_IS0(from))
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return ! B_IS0(to);
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return false;
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}
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vpip_bit_t add_with_carry(vpip_bit_t l, vpip_bit_t r, vpip_bit_t&carry)
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{
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unsigned li, ri, ci;
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if (B_IS1(l)) {
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li = 1;
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} else if (B_IS0(l)) {
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li = 0;
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} else {
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carry = StX;
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return StX;
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}
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if (B_IS1(r)) {
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ri = 1;
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} else if (B_IS0(r)) {
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ri = 0;
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} else {
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carry = StX;
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return StX;
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}
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if (B_IS1(carry)) {
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ci = 1;
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} else if (B_IS0(carry)) {
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ci = 0;
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} else {
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carry = StX;
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return StX;
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}
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unsigned sum = li + ri + ci;
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carry = (sum & 2)? St1 : St0;
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return (sum & 1)? St1 : St0;
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}
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/*
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* $Log: vvm_bit.cc,v $
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* Revision 1.13 2001/01/16 02:44:18 steve
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* Use the iosfwd header if available.
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*
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* Revision 1.12 2000/04/10 05:26:07 steve
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* All events now use the NetEvent class.
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*
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* Revision 1.11 2000/03/26 16:55:41 steve
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* Remove the vvm_bits_t abstract class.
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*
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* Revision 1.10 2000/03/22 04:26:41 steve
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* Replace the vpip_bit_t with a typedef and
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* define values for all the different bit
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* values, including strengths.
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*
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* Revision 1.9 2000/03/16 19:03:04 steve
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* Revise the VVM backend to use nexus objects so that
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* drivers and resolution functions can be used, and
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* the t-vvm module doesn't need to write a zillion
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* output functions.
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*
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* Revision 1.8 2000/02/23 02:56:56 steve
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* Macintosh compilers do not support ident.
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*
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* Revision 1.7 1999/12/02 03:36:01 steve
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* shiftl and shiftr take unsized second parameter.
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*
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* Revision 1.6 1999/11/22 00:30:52 steve
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* Detemplate some and, or and nor methods.
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*
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* Revision 1.5 1999/11/21 00:13:09 steve
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* Support memories in continuous assignments.
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*/
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