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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
*/

# include "config.h"

# include <cstring>
# include <iostream>

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

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

verinum* PEBinary::eval_const(Design*des, 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()) {
res = new verinum(*l + *r);
} else {
res = new verinum(verinum::Vx, l->len());
}
break;
}
case '-': {
if (l->is_defined() && r->is_defined()) {
res = new verinum(*l - *r);
} else {
res = new verinum(verinum::Vx, l->len());
}
break;
}
case '*': {
if (l->is_defined() && r->is_defined()) {
res = new verinum(*l * *r);
} 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;
}
verinum* PEConcat::eval_const(Design*des, NetScope*scope) const
{
      verinum*accum = parms_[0]->eval_const(des, scope);
      if (accum == 0)
return 0;

      for (unsigned idx = 1 ; idx < parms_.count() ; idx += 1) {

verinum*tmp = parms_[idx]->eval_const(des, scope);
if (tmp == 0) {
delete accum;
return 0;
}
assert(tmp);

*accum = concat(*accum, *tmp);
delete tmp;
      }

      return accum;
}


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

      const name_component_t&name_tail = path_.back();

// Handle the special case that this ident is a genvar
// variable name. In that case, the genvar meaning preempts
// everything and we just return that value immediately.
      if (scope->genvar_tmp
&& strcmp(name_tail.name,scope->genvar_tmp) == 0) {
return new verinum(scope->genvar_tmp_val);
      }

      symbol_search(this, des, scope, path_, net, expr, eve);

      if (expr == 0)
return 0;

      const NetEConst*eval = dynamic_cast<const NetEConst*>(expr);
      if (eval == 0) {
cerr << get_fileline() << ": internal error: Unable to evaluate "
<< "constant expression (parameter=" << path_
<< "): " << *expr << endl;
return 0;
      }

      assert(eval);

      if (!name_tail.index.empty())
return 0;


      return new verinum(eval->value());
}

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

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

verinum* PEString::eval_const(Design*, NetScope*) const
{
      return new verinum(string(text_));
}

verinum* PETernary::eval_const(Design*des, 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(Design*des, 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 ((uint64_t)0, 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;
}
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