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net_nex_input.cc

/*
 * Copyright (c) 2002-2008 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 <iostream>

# include  <cassert>
# include  <typeinfo>
# include  "netlist.h"
# include  "netmisc.h"

NexusSet* NetExpr::nex_input(bool rem_out)
{
      cerr << get_fileline()
         << ": internal error: nex_input not implemented: "
         << *this << endl;
      return 0;
}

NexusSet* NetProc::nex_input(bool rem_out)
{
      cerr << get_fileline()
         << ": internal error: NetProc::nex_input not implemented"
         << endl;
      return 0;
}

NexusSet* NetEBinary::nex_input(bool rem_out)
{
      NexusSet*result = left_->nex_input(rem_out);
      NexusSet*tmp = right_->nex_input(rem_out);
      result->add(*tmp);
      delete tmp;
      return result;
}

NexusSet* NetEConcat::nex_input(bool rem_out)
{
      if (parms_[0] == NULL) return NULL;
      NexusSet*result = parms_[0]->nex_input(rem_out);
      for (unsigned idx = 1 ;  idx < parms_.count() ;  idx += 1) {
          if (parms_[idx] == NULL) {
              delete result;
              return NULL;
          }
          NexusSet*tmp = parms_[idx]->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }
      return result;
}

NexusSet* NetEAccess::nex_input(bool rem_out)
{
      return new NexusSet;
}

/*
 * A constant has not inputs, so always return an empty set.
 */
NexusSet* NetEConst::nex_input(bool rem_out)
{
      return new NexusSet;
}

NexusSet* NetECReal::nex_input(bool rem_out)
{
      return new NexusSet;
}

/*
 * A parameter by definition has no inputs. It represents a constant
 * value, even if that value is a constant expression.
 */
NexusSet* NetEParam::nex_input(bool rem_out)
{
      return new NexusSet;
}

NexusSet* NetEEvent::nex_input(bool rem_out)
{
      return new NexusSet;
}

NexusSet* NetEScope::nex_input(bool rem_out)
{
      return new NexusSet;
}

NexusSet* NetESelect::nex_input(bool rem_out)
{
      NexusSet*result = base_? base_->nex_input(rem_out) : new NexusSet();
      NexusSet*tmp = expr_->nex_input(rem_out);
      if (tmp == NULL) {
          delete result;
          return NULL;
      }
      result->add(*tmp);
      delete tmp;
      return result;
}

NexusSet* NetESFunc::nex_input(bool rem_out)
{
      if (nparms_ == 0)
          return new NexusSet;

      NexusSet*result = parms_[0]->nex_input(rem_out);
      for (unsigned idx = 1 ;  idx < nparms_ ;  idx += 1) {
          NexusSet*tmp = parms_[idx]->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }
      return result;
}

NexusSet* NetESignal::nex_input(bool rem_out)
{
      NexusSet*result = new NexusSet;
      for (unsigned idx = 0 ;  idx < net_->pin_count() ;  idx += 1)
          result->add(net_->pin(idx).nexus());

      return result;
}

NexusSet* NetETernary::nex_input(bool rem_out)
{
      NexusSet*tmp;
      NexusSet*result = cond_->nex_input(rem_out);

      tmp = true_val_->nex_input(rem_out);
      result->add(*tmp);
      delete tmp;

      tmp = false_val_->nex_input(rem_out);
      result->add(*tmp);
      delete tmp;

      return result;
}

NexusSet* NetEUFunc::nex_input(bool rem_out)
{
      NexusSet*result = new NexusSet;
      for (unsigned idx = 0 ;  idx < parms_.count() ;  idx += 1) {
          NexusSet*tmp = parms_[idx]->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }

      return result;
}

NexusSet* NetEUnary::nex_input(bool rem_out)
{
      return expr_->nex_input(rem_out);
}

NexusSet* NetAssign_::nex_input(bool rem_out)
{
      NexusSet*result = new NexusSet;
      if (word_) {
          NexusSet*tmp = word_->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }
      if (base_) {
          NexusSet*tmp = base_->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }

      return result;
}

NexusSet* NetAssignBase::nex_input(bool rem_out)
{
      NexusSet*result = rval_->nex_input(rem_out);

      /* It is possible that the lval_ can have nex_input values. In
         particular, index expressions are statement inputs as well,
         so should be addressed here. */
      for (NetAssign_*cur = lval_ ;  cur ;  cur = cur->more) {
          NexusSet*tmp = cur->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }

      return result;
}

/*
 * The nex_input of a begin/end block is the NexusSet of bits that the
 * block reads from outside the block. That means it is the union of
 * the nex_input for all the substatements.
 *
 * The input set for a sequential set is not exactly the union of the
 * input sets because there is the possibility of intermediate values,
 * that don't deserve to be in the input set. To wit:
 *
 *      begin
 *         t = a + b;
 *         c = ~t;
 *      end
 *
 * In this example, "t" should not be in the input set because it is
 * used by the sequence as a temporary value.
 */
NexusSet* NetBlock::nex_input(bool rem_out)
{
      if (last_ == 0)
          return new NexusSet;

      if (type_ == PARA) {
          cerr << get_fileline() << ": internal error: Sorry, "
             << "I don't know how to synthesize fork/join blocks."
             << endl;
          return 0;
      }

      NetProc*cur = last_->next_;
      /* This is the accumulated input set. */
      NexusSet*result = new NexusSet;
      /* This is an accumulated output set. */
      NexusSet*prev = new NexusSet;

      do {
            /* Get the inputs for the current statement. */
          NexusSet*tmp = cur->nex_input(rem_out);

            /* Add the current input set to the accumulated input set. */
          if (tmp != 0) result->add(*tmp);
          delete tmp;

            /* Add the current outputs to the accumulated output set,
             so they can be removed from the input set below. */
          cur->nex_output(*prev);

          cur = cur->next_;
      } while (cur != last_->next_);

        /* Remove from the input set those bits that are outputs
           from other statements. They aren't really inputs
           to the block, just internal intermediate values. */
      if (rem_out) result->rem(*prev);

      return result;
}

/*
 * The inputs to a case statement are the inputs to the expression,
 * the inputs to all the guards, and the inputs to all the guarded
 * statements.
 */
NexusSet* NetCase::nex_input(bool rem_out)
{
      NexusSet*result = expr_->nex_input(rem_out);
      if (result == 0)
          return 0;

      for (unsigned idx = 0 ;  idx < nitems_ ;  idx += 1) {

            /* Skip cases that have empty statements. */
          if (items_[idx].statement == 0)
              continue;

          NexusSet*tmp = items_[idx].statement->nex_input(rem_out);
          assert(tmp);
          result->add(*tmp);
          delete tmp;

            /* Usually, this is the guard expression. The default
             case is special and is identified by a null
             guard. The default guard obviously has no input. */
          if (items_[idx].guard) {
              tmp = items_[idx].guard->nex_input(rem_out);
              assert(tmp);
              result->add(*tmp);
              delete tmp;
          }
      }

      return result;
}

NexusSet* NetCAssign::nex_input(bool rem_out)
{
      cerr << get_fileline() << ": internal warning: NetCAssign::nex_input()"
         << " not implemented." << endl;
      return new NexusSet;
}

NexusSet* NetCondit::nex_input(bool rem_out)
{
      NexusSet*result = expr_->nex_input(rem_out);
      if (if_ != 0) {
          NexusSet*tmp = if_->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }

      if (else_ != 0) {
          NexusSet*tmp = else_->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }

      return result;
}

NexusSet* NetForce::nex_input(bool rem_out)
{
      cerr << get_fileline() << ": internal warning: NetForce::nex_input()"
         << " not implemented." << endl;
      return new NexusSet;
}

NexusSet* NetForever::nex_input(bool rem_out)
{
      NexusSet*result = statement_->nex_input(rem_out);
      return result;
}

/*
 * The NetPDelay statement is a statement of the form
 *
 *   #<expr> <statement>
 *
 * The nex_input set is the input set of the <statement>. Do *not*
 * include the input set of the <expr> because it does not affect the
 * result. The statement can be omitted.
 */
NexusSet* NetPDelay::nex_input(bool rem_out)
{
      if (statement_ == 0) return 0;
      NexusSet*result = statement_->nex_input(rem_out);
      return result;
}

NexusSet* NetRepeat::nex_input(bool rem_out)
{
      NexusSet*result = statement_->nex_input(rem_out);
      NexusSet*tmp = expr_->nex_input(rem_out);
      result->add(*tmp);
      delete tmp;
      return result;
}

NexusSet* NetSTask::nex_input(bool rem_out)
{
      if (parms_.count() == 0)
          return new NexusSet;

      NexusSet*result = parms_[0]->nex_input(rem_out);
      for (unsigned idx = 1 ;  idx < parms_.count() ;  idx += 1) {
          NexusSet*tmp = parms_[idx]->nex_input(rem_out);
          result->add(*tmp);
          delete tmp;
      }

      return result;
}

/*
 * The NetUTask represents a call to a user defined task. There are no
 * parameters to consider, because the compiler already removed them
 * and converted them to blocking assignments.
 */
NexusSet* NetUTask::nex_input(bool rem_out)
{
      return new NexusSet;
}

NexusSet* NetWhile::nex_input(bool rem_out)
{
      NexusSet*result = proc_->nex_input(rem_out);
      NexusSet*tmp = cond_->nex_input(rem_out);
      result->add(*tmp);
      delete tmp;
      return result;
}

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