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Evaluate logical not at elaboration time.

This commit is contained in:
steve 2002-04-14 21:16:48 +00:00
parent 6d4c6b56f6
commit ea44866b2f
1 changed files with 41 additions and 1 deletions
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42
elab_expr.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_expr.cc,v 1.53 2002/04/14 03:55:25 steve Exp $" #ident "$Id: elab_expr.cc,v 1.54 2002/04/14 21:16:48 steve Exp $"
#endif #endif
# include "config.h" # include "config.h"
@ -687,6 +687,43 @@ NetExpr* PEUnary::elaborate_expr(Design*des, NetScope*scope, bool) const
break; break;
case '!': // Logical NOT case '!': // Logical NOT
/* If the operand to unary ! is a constant, then I can
evaluate this expression here and return a logical
constant in its place. */
if (NetEConst*ipc = dynamic_cast<NetEConst*>(ip)) {
verinum val = ipc->value();
unsigned v1 = 0;
unsigned vx = 0;
for (unsigned idx = 0 ; idx < val.len() ; idx += 1)
switch (val[idx]) {
case verinum::V0:
break;
case verinum::V1:
v1 += 1;
break;
default:
vx += 1;
break;
}
verinum::V res;
if (v1 > 0)
res = verinum::V0;
else if (vx > 0)
res = verinum::Vx;
else
res = verinum::V1;
verinum vres (res, 1, true);
tmp = new NetEConst(vres);
tmp->set_line(*this);
delete ip;
} else {
tmp = new NetEUReduce(op_, ip);
tmp->set_line(*this);
}
break;
case '&': // Reduction AND case '&': // Reduction AND
case '|': // Reduction OR case '|': // Reduction OR
case '^': // Reduction XOR case '^': // Reduction XOR
@ -708,6 +745,9 @@ NetExpr* PEUnary::elaborate_expr(Design*des, NetScope*scope, bool) const
/* /*
* $Log: elab_expr.cc,v $ * $Log: elab_expr.cc,v $
* Revision 1.54 2002/04/14 21:16:48 steve
* Evaluate logical not at elaboration time.
*
* Revision 1.53 2002/04/14 03:55:25 steve * Revision 1.53 2002/04/14 03:55:25 steve
* Precalculate unary - if possible. * Precalculate unary - if possible.
* *