luke
/
iverilog
mirror of https://github.com/steveicarus/iverilog.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Eval ^ and &0 expressions.

This commit is contained in:
steve 2002-05-25 16:43:47 +00:00
parent 57f2ad6d15
commit 6bd8ab46d5
1 changed files with 41 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
eval_tree.cc
View File

@ -17,7 +17,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT) && !defined(macintosh)
#ident "$Id: eval_tree.cc,v 1.39 2002/05/06 02:30:27 steve Exp $"
#ident "$Id: eval_tree.cc,v 1.40 2002/05/25 16:43:47 steve Exp $"
#endif
# include "config.h"
@ -81,8 +81,22 @@ NetEConst* NetEBBits::eval_tree()
eval_sub_tree_();
NetEConst*lc = dynamic_cast<NetEConst*>(left_);
if (lc == 0) return 0;
NetEConst*rc = dynamic_cast<NetEConst*>(right_);
/* Notice the special case where one of the operands is 0 and
this is a bitwise &. If this happens, then the result is
known to be 0. */
if ((op() == '&') && lc && (lc->value() == verinum(0))) {
verinum res (verinum::V0, expr_width());
return new NetEConst(res);
}
if ((op() == '&') && rc && (rc->value() == verinum(0))) {
verinum res (verinum::V0, expr_width());
return new NetEConst(res);
}
if (lc == 0) return 0;
if (rc == 0) return 0;
verinum lval = lc->value();
@ -1088,6 +1102,28 @@ NetEConst* NetEUReduce::eval_tree()
break;
}
case '^': {
/* Reduction XOR. */
unsigned ones = 0, unknown = 0;
for (unsigned idx = 0 ; idx < val.len() ; idx += 1)
switch (val.get(idx)) {
case verinum::V0:
break;
case verinum::V1:
ones += 1;
break;
default:
unknown += 1;
break;
}
if (unknown)
return new NetEConst(verinum(verinum::Vx,1,true));
if (ones%2)
return new NetEConst(verinum(verinum::V1,1,true));
return new NetEConst(verinum(verinum::V0,1,true));
}
default:
return 0;
}
@ -1098,6 +1134,9 @@ NetEConst* NetEUReduce::eval_tree()
/*
* $Log: eval_tree.cc,v $
* Revision 1.40 2002/05/25 16:43:47 steve
* Eval ^ and &0 expressions.
*
* Revision 1.39 2002/05/06 02:30:27 steve
* Allow parameters in concatenation of widths are defined.
*