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Propagate constants through xnor gates. (PR#51)

This commit is contained in:
steve 2000-11-23 01:55:52 +00:00
parent 92424eea10
commit e33fb3ce51
1 changed files with 32 additions and 9 deletions
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41
cprop.cc
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@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT) && !defined(macintosh)
#ident "$Id: cprop.cc,v 1.21 2000/11/19 05:26:58 steve Exp $"
#ident "$Id: cprop.cc,v 1.22 2000/11/23 01:55:52 steve Exp $"
#endif
# include "netlist.h"
@ -461,6 +461,7 @@ void cprop_functor::lpm_logic(Design*des, NetLogic*obj)
break;
}
case NetLogic::XNOR:
case NetLogic::XOR: {
unsigned top = obj->pin_count();
unsigned idx = 1;
@ -536,7 +537,10 @@ void cprop_functor::lpm_logic(Design*des, NetLogic*obj)
/* If all the inputs were eliminated, then replace
the gate with a constant 0 and I am done. */
if (top == 1) {
NetConst*tmp = new NetConst(obj->name(), verinum::V0);
verinum::V out = obj->type()==NetLogic::XNOR
? verinum::V1
: verinum::V0;
NetConst*tmp = new NetConst(obj->name(), out);
des->add_node(tmp);
tmp->pin(0).drive0(obj->pin(0).drive0());
@ -561,9 +565,17 @@ void cprop_functor::lpm_logic(Design*des, NetLogic*obj)
else
save = 2;
NetLogic*tmp = new NetLogic(obj->scope(),
obj->name(), 2,
NetLogic::NOT);
NetLogic*tmp;
if (obj->type() == NetLogic::XOR)
tmp = new NetLogic(obj->scope(),
obj->name(), 2,
NetLogic::NOT);
else
tmp = new NetLogic(obj->scope(),
obj->name(), 2,
NetLogic::BUF);
des->add_node(tmp);
tmp->pin(0).drive0(obj->pin(0).drive0());
tmp->pin(0).drive1(obj->pin(0).drive1());
@ -578,9 +590,17 @@ void cprop_functor::lpm_logic(Design*des, NetLogic*obj)
/* If we are down to only one input, then replace
the XOR with a BUF and exit now. */
if (top == 2) {
NetLogic*tmp = new NetLogic(obj->scope(),
obj->name(), 2,
NetLogic::BUF);
NetLogic*tmp;
if (obj->type() == NetLogic::XOR)
tmp = new NetLogic(obj->scope(),
obj->name(), 2,
NetLogic::BUF);
else
tmp = new NetLogic(obj->scope(),
obj->name(), 2,
NetLogic::NOT);
des->add_node(tmp);
tmp->pin(0).drive0(obj->pin(0).drive0());
tmp->pin(0).drive1(obj->pin(0).drive1());
@ -597,7 +617,7 @@ void cprop_functor::lpm_logic(Design*des, NetLogic*obj)
if (top < obj->pin_count()) {
NetLogic*tmp = new NetLogic(obj->scope(),
obj->name(), top,
NetLogic::XOR);
obj->type());
des->add_node(tmp);
tmp->pin(0).drive0(obj->pin(0).drive0());
tmp->pin(0).drive1(obj->pin(0).drive1());
@ -769,6 +789,9 @@ void cprop(Design*des)
/*
* $Log: cprop.cc,v $
* Revision 1.22 2000/11/23 01:55:52 steve
* Propagate constants through xnor gates. (PR#51)
*
* Revision 1.21 2000/11/19 05:26:58 steve
* Replace AND constand propagation.
*