/**CFile****************************************************************

  FileName    [llb2Cex.c]

  SystemName  [ABC: Logic synthesis and verification system.]

  PackageName [BDD based reachability.]

  Synopsis    [Non-linear quantification scheduling.]

  Author      [Alan Mishchenko]
  
  Affiliation [UC Berkeley]

  Date        [Ver. 1.0. Started - June 20, 2005.]

  Revision    [$Id: llb2Cex.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]

***********************************************************************/

#include "llbInt.h"
#include "cnf.h"
#include "satSolver.h"

ABC_NAMESPACE_IMPL_START
 

////////////////////////////////////////////////////////////////////////
///                        DECLARATIONS                              ///
////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////
///                     FUNCTION DEFINITIONS                         ///
////////////////////////////////////////////////////////////////////////

/**Function*************************************************************

  Synopsis    [Translates a sequence of states into a counter-example.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Cex_t * Llb4_Nonlin4TransformCex( Aig_Man_t * pAig, Vec_Ptr_t * vStates, int fVerbose )
{
    Abc_Cex_t * pCex;
    Cnf_Dat_t * pCnf;
    Vec_Int_t * vAssumps;
    sat_solver * pSat;
    Aig_Obj_t * pObj;
    unsigned * pNext, * pThis;
    int i, k, iBit, status, nRegs, clk = clock();
/*
    Vec_PtrForEachEntry( unsigned *, vStates, pNext, i )
    {
        printf( "%4d : ", i );
        Extra_PrintBinary( stdout, pNext, Aig_ManRegNum(pAig) );
        printf( "\n" );
    }
*/
    // derive SAT solver
    nRegs = Aig_ManRegNum(pAig); pAig->nRegs = 0;
    pCnf = Cnf_Derive( pAig, Aig_ManPoNum(pAig) );
    pAig->nRegs = nRegs;
//    Cnf_DataTranformPolarity( pCnf, 0 );
    // convert into SAT solver
    pSat = (sat_solver *)Cnf_DataWriteIntoSolver( pCnf, 1, 0 );
    if ( pSat == NULL )
    {
        printf( "Llb4_Nonlin4TransformCex(): Counter-example generation has failed.\n" );
        Cnf_DataFree( pCnf );
        return NULL;
    }
    // simplify the problem
    status = sat_solver_simplify(pSat);
    if ( status == 0 )
    {
        printf( "Llb4_Nonlin4TransformCex(): SAT solver is invalid.\n" );
        sat_solver_delete( pSat );
        Cnf_DataFree( pCnf );
        return NULL;
    }
    // start the counter-example
    pCex = Abc_CexAlloc( Saig_ManRegNum(pAig), Saig_ManPiNum(pAig), Vec_PtrSize(vStates) );
    pCex->iFrame = Vec_PtrSize(vStates)-1;
    pCex->iPo = -1;

    // solve each time frame
    iBit = Saig_ManRegNum(pAig);
    pThis = Vec_PtrEntry( vStates, 0 );
    vAssumps = Vec_IntAlloc( 2 * Aig_ManRegNum(pAig) );
    Vec_PtrForEachEntryStart( unsigned *, vStates, pNext, i, 1 )
    {
        // create assumptions
        Vec_IntClear( vAssumps );
        Saig_ManForEachLo( pAig, pObj, k )
            Vec_IntPush( vAssumps, toLitCond( pCnf->pVarNums[Aig_ObjId(pObj)], !Aig_InfoHasBit(pThis,k) ) );
        Saig_ManForEachLi( pAig, pObj, k )
            Vec_IntPush( vAssumps, toLitCond( pCnf->pVarNums[Aig_ObjId(pObj)], !Aig_InfoHasBit(pNext,k) ) );
        // solve SAT problem
        status = sat_solver_solve( pSat, Vec_IntArray(vAssumps), Vec_IntArray(vAssumps) + Vec_IntSize(vAssumps), 
            (ABC_INT64_T)0, (ABC_INT64_T)0, (ABC_INT64_T)0, (ABC_INT64_T)0 );
        // if the problem is SAT, get the counterexample
        if ( status != l_True )
        {
            printf( "Llb4_Nonlin4TransformCex(): There is no transition between state %d and %d.\n", i-1, i );
            Vec_IntFree( vAssumps );
            sat_solver_delete( pSat );
            Cnf_DataFree( pCnf );
            ABC_FREE( pCex );
            return NULL;
        }
        // get the assignment of PIs
        Saig_ManForEachPi( pAig, pObj, k )
            if ( sat_solver_var_value(pSat, pCnf->pVarNums[Aig_ObjId(pObj)]) )
                Aig_InfoSetBit( pCex->pData, iBit + k );
        // update the counter
        iBit += Saig_ManPiNum(pAig);
        pThis = pNext;
    }

    // add the last frame when the property fails
    Vec_IntClear( vAssumps );
    Saig_ManForEachPo( pAig, pObj, k )
        Vec_IntPush( vAssumps, toLitCond( pCnf->pVarNums[Aig_ObjId(pObj)], 0 ) );
    // add clause
    status = sat_solver_addclause( pSat, Vec_IntArray(vAssumps), Vec_IntArray(vAssumps) + Vec_IntSize(vAssumps) );
    if ( status == 0 )
    {
        printf( "Llb4_Nonlin4TransformCex(): The SAT solver is unsat after adding last clause.\n" );
        Vec_IntFree( vAssumps );
        sat_solver_delete( pSat );
        Cnf_DataFree( pCnf );
        ABC_FREE( pCex );
        return NULL;
    }
    // create assumptions
    Vec_IntClear( vAssumps );
    Saig_ManForEachLo( pAig, pObj, k )
        Vec_IntPush( vAssumps, toLitCond( pCnf->pVarNums[Aig_ObjId(pObj)], !Aig_InfoHasBit(pThis,k) ) );
    // solve the last frame
    status = sat_solver_solve( pSat, Vec_IntArray(vAssumps), Vec_IntArray(vAssumps) + Vec_IntSize(vAssumps), 
        (ABC_INT64_T)0, (ABC_INT64_T)0, (ABC_INT64_T)0, (ABC_INT64_T)0 );
    if ( status != l_True )
    {
        printf( "Llb4_Nonlin4TransformCex(): There is no last transition that makes the property fail.\n" );
        Vec_IntFree( vAssumps );
        sat_solver_delete( pSat );
        Cnf_DataFree( pCnf );
        ABC_FREE( pCex );
        return NULL;
    }
    // get the assignment of PIs
    Saig_ManForEachPi( pAig, pObj, k )
        if ( sat_solver_var_value(pSat, pCnf->pVarNums[Aig_ObjId(pObj)]) )
            Aig_InfoSetBit( pCex->pData, iBit + k );
    iBit += Saig_ManPiNum(pAig);
    assert( iBit == pCex->nBits );

    // free the sat_solver
    Vec_IntFree( vAssumps );
    sat_solver_delete( pSat );
    Cnf_DataFree( pCnf );

    // verify counter-example
    status = Saig_ManFindFailedPoCex( pAig, pCex );
    if ( status >= 0 && status < Saig_ManPoNum(pAig) )
        pCex->iPo = status;
    else
    {
        printf( "Inter_ManGetCounterExample(): Counter-example verification has FAILED.\n" );
        ABC_FREE( pCex );
        return NULL;
    }
    // report the results
//    if ( fVerbose )
//        Abc_PrintTime( 1, "SAT-based cex generation time", clock() - clk );
    return pCex;
}


////////////////////////////////////////////////////////////////////////
///                       END OF FILE                                ///
////////////////////////////////////////////////////////////////////////


ABC_NAMESPACE_IMPL_END