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/*
* Copyright (c) 1998-1999 Stephen Williams (steve@icarus.com)
*
* This source code is free software; you can redistribute it
* and/or modify it in source code form under the terms of the GNU
* General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#if !defined(WINNT) && !defined(macintosh)
#ident "$Id: eval.cc,v 1.26 2001/12/29 22:10:10 steve Exp $"
#endif

# include "config.h"

# include <iostream>

# include "PExpr.h"
# include "netlist.h"
# include "compiler.h"

verinum* PExpr::eval_const(const Design*, const NetScope*) const
{
      return 0;
}

verinum* PEBinary::eval_const(const Design*des, const NetScope*scope) const
{
      verinum*l = left_->eval_const(des, scope);
      if (l == 0) return 0;
      verinum*r = right_->eval_const(des, scope);
      if (r == 0) {
delete l;
return 0;
      }
      verinum*res;

      switch (op_) {
case '+': {
if (l->is_defined() && r->is_defined()) {
long lv = l->as_long();
long rv = r->as_long();
res = new verinum(lv+rv, l->len());
} else {
res = new verinum(verinum::Vx, l->len());
}
break;
}
case '-': {
if (l->is_defined() && r->is_defined()) {
long lv = l->as_long();
long rv = r->as_long();
res = new verinum(lv-rv, l->len());
} else {
res = new verinum(verinum::Vx, l->len());
}
break;
}
case '*': {
if (l->is_defined() && r->is_defined()) {
long lv = l->as_long();
long rv = r->as_long();
res = new verinum(lv * rv, l->len());
} else {
res = new verinum(verinum::Vx, l->len());
}
break;
}
case '/': {
if (l->is_defined() && r->is_defined()) {
long lv = l->as_long();
long rv = r->as_long();
res = new verinum(lv / rv, l->len());
} else {
res = new verinum(verinum::Vx, l->len());
}
break;
}
case '%': {
if (l->is_defined() && r->is_defined()) {
long lv = l->as_long();
long rv = r->as_long();
res = new verinum(lv % rv, l->len());
} else {
res = new verinum(verinum::Vx, l->len());
}
break;
}
case 'l': { // left shift (<<)
assert(r->is_defined());
unsigned long rv = r->as_ulong();
res = new verinum(verinum::V0, l->len());
if (rv < res->len()) {
unsigned cnt = res->len() - rv;
for (unsigned idx = 0 ; idx < cnt ; idx += 1)
res->set(idx+rv, l->get(idx));
}
break;
}
case 'r': { // right shift (>>)
assert(r->is_defined());
unsigned long rv = r->as_ulong();
res = new verinum(verinum::V0, l->len());
if (rv < res->len()) {
unsigned cnt = res->len() - rv;
for (unsigned idx = 0 ; idx < cnt ; idx += 1)
res->set(idx, l->get(idx+rv));
}
break;
}

default:
delete l;
delete r;
return 0;
      }

      delete l;
      delete r;
      return res;
}


/*
* Evaluate an identifier as a constant expression. This is only
* possible if the identifier is that of a parameter.
*/
verinum* PEIdent::eval_const(const Design*des, const NetScope*scope) const
{
      assert(scope);
      const NetExpr*expr = des->find_parameter(scope, path_);

      if (expr == 0)
return 0;

      assert(msb_ == 0);

      if (dynamic_cast<const NetEParam*>(expr)) {
cerr << get_line() << ": sorry: I cannot evaluate ``" <<
path_ << "'' in this scope: " << scope->name() << endl;
return 0;
      }

      const NetEConst*eval = dynamic_cast<const NetEConst*>(expr);
      assert(eval);
      return new verinum(eval->value());
}

verinum* PEFNumber::eval_const(const Design*, const NetScope*) const
{
      long val = value_->as_long();
      return new verinum(val);
}

verinum* PENumber::eval_const(const Design*, const NetScope*) const
{
      return new verinum(value());
}

verinum* PETernary::eval_const(const Design*des, const NetScope*scope) const
{
      verinum*test = expr_->eval_const(des, scope);
      if (test == 0)
return 0;

      verinum::V bit = test->get(0);
      delete test;
      switch (bit) {
case verinum::V0:
return fal_->eval_const(des, scope);
case verinum::V1:
return tru_->eval_const(des, scope);
default:
return 0;
// XXXX It is possible to handle this case if both fal_
// and tru_ are constant. Someday...
      }
}

verinum* PEUnary::eval_const(const Design*des, const NetScope*scope) const
{
      verinum*val = expr_->eval_const(des, scope);
      if (val == 0)
return 0;

      switch (op_) {
case '+':
return val;

case '-': {
/* We need to expand the value a bit if we are
taking the 2's complement so that we are
guaranteed to not overflow. */
verinum tmp (0UL, val->len()+1);
for (unsigned idx = 0 ; idx < val->len() ; idx += 1)
tmp.set(idx, val->get(idx));

*val = v_not(tmp) + verinum(verinum::V1, 1);
val->has_sign(true);
return val;
}

      }
delete val;
      return 0;
}


/*
* $Log: eval.cc,v $
* Revision 1.26 2001/12/29 22:10:10 steve
* constant eval of arithmetic with x and z.
*
* Revision 1.25 2001/12/29 00:43:55 steve
* Evaluate constant right shifts.
*
* Revision 1.24 2001/12/03 04:47:15 steve
* Parser and pform use hierarchical names as hname_t
* objects instead of encoded strings.
*
* Revision 1.23 2001/11/07 04:01:59 steve
* eval_const uses scope instead of a string path.
*
* Revision 1.22 2001/11/06 06:11:55 steve
* Support more real arithmetic in delay constants.
*
* Revision 1.21 2001/07/25 03:10:49 steve
* Create a config.h.in file to hold all the config
* junk, and support gcc 3.0. (Stephan Boettcher)
*
* Revision 1.20 2001/02/09 02:49:59 steve
* Be more clear about scope of failure.
*
* Revision 1.19 2001/01/27 05:41:48 steve
* Fix sign extension of evaluated constants. (PR#91)
*
* Revision 1.18 2001/01/14 23:04:56 steve
* Generalize the evaluation of floating point delays, and
* get it working with delay assignment statements.
*
* Allow parameters to be referenced by hierarchical name.
*
* Revision 1.17 2001/01/04 04:47:51 steve
* Add support for << is signal indices.
*
* Revision 1.16 2000/12/10 22:01:36 steve
* Support decimal constants in behavioral delays.
*
* Revision 1.15 2000/09/07 22:38:13 steve
* Support unary + and - in constants.
*/
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