satcheck_picosat.cpp

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/*******************************************************************\
 
Module:
 
Author: Michael Tautschnig, michael.tautschnig@cs.ox.ac.uk
 
\*******************************************************************/
 
#include "satcheck_picosat.h"
 
#include <algorithm>
 
#include <util/invariant.h>
#include <util/threeval.h>
 
extern "C"
{
#include <picosat.h>
}
 
#ifndef HAVE_PICOSAT
#error "Expected HAVE_PICOSAT"
#endif
 
tvt satcheck_picosatt::l_get(literalt a) const
{
  if(a.is_constant())
    return tvt(a.sign());
 
  tvt result;
 
  if(static_cast<int>(a.var_no())>picosat_variables(picosat))
    return tvt(tvt::tv_enumt::TV_UNKNOWN);
 
  const int val=picosat_deref(picosat, a.dimacs());
  if(val>0)
    result=tvt(true);
  else if(val<0)
    result=tvt(false);
  else
    return tvt(tvt::tv_enumt::TV_UNKNOWN);
 
  return result;
}
 
std::string satcheck_picosatt::solver_text() const
{
  return "PicoSAT";
}
 
void satcheck_picosatt::lcnf(const bvt &bv)
{
  bvt new_bv;
 
  if(process_clause(bv, new_bv))
    return;
 
  picosat_adjust(picosat, _no_variables);
 
  for(const auto &literal : new_bv)
    picosat_add(picosat, literal.dimacs());
 
  picosat_add(picosat, 0);
 
  clause_counter++;
}
 
propt::resultt satcheck_picosatt::do_prop_solve(const bvt &assumptions)
{
  PRECONDITION(status != ERROR);
 
  {
    std::string msg=
      std::to_string(_no_variables-1)+" variables, "+
      std::to_string(picosat_added_original_clauses(picosat))+" clauses";
    log.statistics() << msg << messaget::eom;
  }
 
  std::string msg;
 
  for(const auto &literal : assumptions)
    if(!literal.is_true())
      picosat_assume(picosat, literal.dimacs());
 
  const int res=picosat_sat(picosat, -1);
  if(res==PICOSAT_SATISFIABLE)
  {
    msg="SAT checker: instance is SATISFIABLE";
    log.status() << msg << messaget::eom;
    status=SAT;
    return P_SATISFIABLE;
  }
  else
  {
    INVARIANT(
      res == PICOSAT_UNSATISFIABLE,
      "picosat result should report either sat or unsat");
    msg="SAT checker: instance is UNSATISFIABLE";
    log.status() << msg << messaget::eom;
  }
 
  status=UNSAT;
  return P_UNSATISFIABLE;
}
 
void satcheck_picosatt::set_assignment(literalt a, bool value)
{
  UNREACHABLE;
}
 
satcheck_picosatt::satcheck_picosatt()
{
  picosat = picosat_init();
}
 
satcheck_picosatt::~satcheck_picosatt()
{
  picosat_reset(picosat);
}
 
bool satcheck_picosatt::is_in_conflict(literalt a) const
{
  PRECONDITION(!a.is_constant());
 
  return picosat_failed_assumption(picosat, a.dimacs())!=0;
}