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Eleminate reduction gate for 1-bit compares.

This commit is contained in:
steve 2000-07-08 04:59:20 +00:00
parent 18eb34921f
commit 9b59001cf9
1 changed files with 30 additions and 1 deletions
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31
elab_net.cc
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@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/ */
#if !defined(WINNT) && !defined(macintosh) #if !defined(WINNT) && !defined(macintosh)
#ident "$Id: elab_net.cc,v 1.40 2000/07/06 18:13:24 steve Exp $" #ident "$Id: elab_net.cc,v 1.41 2000/07/08 04:59:20 steve Exp $"
#endif #endif
# include "PExpr.h" # include "PExpr.h"
@ -441,6 +441,19 @@ NetNet* PEBinary::elaborate_net_cmp_(Design*des, const string&path,
case 'e': // == case 'e': // ==
/* Handle the special case of single bit compare with a
single XNOR gate. This is easy and direct. */
if (dwidth == 1) {
gate = new NetLogic(des->local_symbol(path),
3, NetLogic::XNOR);
connect(gate->pin(0), osig->pin(0));
connect(gate->pin(1), lsig->pin(0));
connect(gate->pin(2), rsig->pin(0));
break;
}
/* Oh well, do the general case. */
gate = new NetLogic(des->local_symbol(path), gate = new NetLogic(des->local_symbol(path),
1+dwidth,NetLogic::AND); 1+dwidth,NetLogic::AND);
connect(gate->pin(0), osig->pin(0)); connect(gate->pin(0), osig->pin(0));
@ -465,9 +478,22 @@ NetNet* PEBinary::elaborate_net_cmp_(Design*des, const string&path,
tmp->local_flag(true); tmp->local_flag(true);
connect(cmp->pin(0), tmp->pin(0)); connect(cmp->pin(0), tmp->pin(0));
} }
break; break;
case 'n': // != case 'n': // !=
/* Handle the special case of single bit compare with a
single XOR gate. This is easy and direct. */
if (dwidth == 1) {
gate = new NetLogic(des->local_symbol(path),
3, NetLogic::XOR);
connect(gate->pin(0), osig->pin(0));
connect(gate->pin(1), lsig->pin(0));
connect(gate->pin(2), rsig->pin(0));
break;
}
gate = new NetLogic(des->local_symbol(path), gate = new NetLogic(des->local_symbol(path),
1+dwidth, NetLogic::OR); 1+dwidth, NetLogic::OR);
connect(gate->pin(0), osig->pin(0)); connect(gate->pin(0), osig->pin(0));
@ -1578,6 +1604,9 @@ NetNet* PEUnary::elaborate_net(Design*des, const string&path,
/* /*
* $Log: elab_net.cc,v $ * $Log: elab_net.cc,v $
* Revision 1.41 2000/07/08 04:59:20 steve
* Eleminate reduction gate for 1-bit compares.
*
* Revision 1.40 2000/07/06 18:13:24 steve * Revision 1.40 2000/07/06 18:13:24 steve
* Connect all the l and r bits of a NE expression. * Connect all the l and r bits of a NE expression.
* *