text: /*
   * Copyright 2018 Google, Inc.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met: redistributions of source code must retain the above copyright
   * notice, this list of conditions and the following disclaimer;
   * redistributions in binary form must reproduce the above copyright
   * notice, this list of conditions and the following disclaimer in the
   * documentation and/or other materials provided with the distribution;
   * neither the name of the copyright holders nor the names of its
   * contributors may be used to endorse or promote products derived from
   * this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "systemc/core/process.hh"
  #include "systemc/core/scheduler.hh"
  #include "systemc/ext/channel/sc_signal_resolved.hh"
  #include "systemc/ext/core/sc_module.hh" // for sc_gen_unique_name
  
  namespace sc_core
  {
  
  sc_signal_resolved::sc_signal_resolved() : sc_interface(),
          sc_signal<sc_dt::sc_logic, SC_MANY_WRITERS>(
                  sc_gen_unique_name("signal_resolved"))
  {}
  
  sc_signal_resolved::sc_signal_resolved(const char *name) :
          sc_interface(), sc_signal<sc_dt::sc_logic, SC_MANY_WRITERS>(name)
  {}
  
  sc_signal_resolved::~sc_signal_resolved() {}
  void sc_signal_resolved::register_port(sc_port_base &, const char *) {}
  
  void
  sc_signal_resolved::write(const sc_dt::sc_logic &l)
  {
      ::sc_gem5::Process *p = ::sc_gem5::scheduler.current();
  
      auto it = inputs.find(p);
      if (it == inputs.end()) {
          inputs.emplace(p, l);
          request_update();
      } else if (it->second != l) {
          it->second = l;
          request_update();
      }
  }
  
  sc_signal_resolved &
  sc_signal_resolved::operator = (const sc_dt::sc_logic &l)
  {
      write(l);
      return *this;
  }
  
  sc_signal_resolved &
  sc_signal_resolved::operator = (const sc_signal_resolved &r)
  {
      write(r.read());
      return *this;
  }
  
  void
  sc_signal_resolved::update()
  {
      using sc_dt::Log_0;
      using sc_dt::Log_1;
      using sc_dt::Log_Z;
      using sc_dt::Log_X;
      static sc_dt::sc_logic_value_t merge_table[4][4] = {
          { Log_0, Log_X, Log_0, Log_X },
          { Log_X, Log_1, Log_1, Log_X },
          { Log_0, Log_1, Log_Z, Log_X },
          { Log_X, Log_X, Log_X, Log_X }
      };
  
      // Resolve the inputs, and give the result to the underlying signal class.
      m_new_val = Log_Z;
      for (auto &input: inputs)
          m_new_val = merge_table[m_new_val.value()][input.second.value()];
  
      // Ask the signal to update it's value.
      sc_signal<sc_dt::sc_logic, SC_MANY_WRITERS>::update();
  }
  
  } // namespace sc_core
  