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+/**CFile****************************************************************
+
+ FileName [giaSolver.c]
+
+ SystemName [ABC: Logic synthesis and verification system.]
+
+ PackageName [Scalable AIG package.]
+
+ Synopsis [Circuit-based SAT solver.]
+
+ Author [Alan Mishchenko]
+
+ Affiliation [UC Berkeley]
+
+ Date [Ver. 1.0. Started - June 20, 2005.]
+
+ Revision [$Id: giaSolver.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "gia.h"
+
+////////////////////////////////////////////////////////////////////////
+/// DECLARATIONS ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Sat_Man_t_ Sat_Man_t;
+struct Sat_Man_t_
+{
+ Gia_Man_t * pGia; // the original AIG manager
+ Vec_Int_t * vModel; // satisfying PI assignment
+ int nConfs; // cur number of conflicts
+ int nConfsMax; // max number of conflicts
+ int iHead; // variable queue
+ int iTail; // variable queue
+ int iJust; // head of justification
+ int nTrail; // variable queue size
+ int pTrail[0]; // variable queue data
+};
+
+static inline int Sat_VarIsAssigned( Gia_Obj_t * pVar ) { return pVar->fMark0; }
+static inline void Sat_VarAssign( Gia_Obj_t * pVar ) { assert(!pVar->fMark0); pVar->fMark0 = 1; }
+static inline void Sat_VarUnassign( Gia_Obj_t * pVar ) { assert(pVar->fMark0); pVar->fMark0 = 0; }
+static inline int Sat_VarValue( Gia_Obj_t * pVar ) { assert(pVar->fMark0); return pVar->fMark1; }
+static inline void Sat_VarSetValue( Gia_Obj_t * pVar, int v ) { assert(pVar->fMark0); pVar->fMark1 = v; }
+
+extern void Cec_ManPatVerifyPattern( Gia_Man_t * p, Gia_Obj_t * pObj, Vec_Int_t * vPat );
+extern void Cec_ManPatCleanMark0( Gia_Man_t * p, Gia_Obj_t * pObj );
+
+////////////////////////////////////////////////////////////////////////
+/// FUNCTION DEFINITIONS ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+Sat_Man_t * Sat_ManCreate( Gia_Man_t * pGia )
+{
+ Sat_Man_t * p;
+ p = (Sat_Man_t *)ABC_ALLOC( char, sizeof(Sat_Man_t) + sizeof(int)*Gia_ManObjNum(pGia) );
+ memset( p, 0, sizeof(Sat_Man_t) );
+ p->pGia = pGia;
+ p->nTrail = Gia_ManObjNum(pGia);
+ p->vModel = Vec_IntAlloc( 1000 );
+ return p;
+}
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+void Sat_ManDelete( Sat_Man_t * p )
+{
+ Vec_IntFree( p->vModel );
+ ABC_FREE( p );
+}
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+static inline void Sat_ManCancelUntil( Sat_Man_t * p, int iBound )
+{
+ Gia_Obj_t * pVar;
+ int i;
+ for ( i = p->iTail-1; i >= iBound; i-- )
+ {
+ pVar = Gia_ManObj( p->pGia, p->pTrail[i] );
+ Sat_VarUnassign( pVar );
+ }
+ p->iTail = p->iTail = iBound;
+}
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+static inline void Sat_ManDeriveModel( Sat_Man_t * p )
+{
+ Gia_Obj_t * pVar;
+ int i;
+ Vec_IntClear( p->vModel );
+ for ( i = 0; i < p->iTail; i++ )
+ {
+ pVar = Gia_ManObj( p->pGia, p->pTrail[i] );
+ if ( Gia_ObjIsCi(pVar) )
+ Vec_IntPush( p->vModel, Gia_ObjCioId(pVar) );
+ }
+}
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+static inline void Sat_ManEnqueue( Sat_Man_t * p, Gia_Obj_t * pVar, int Value )
+{
+ assert( p->iTail < p->nTrail );
+ Sat_VarAssign( pVar );
+ Sat_VarSetValue( pVar, Value );
+ p->pTrail[p->iTail++] = Gia_ObjId(p->pGia, pVar);
+}
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+static inline void Sat_ManAssume( Sat_Man_t * p, Gia_Obj_t * pVar, int Value )
+{
+ assert( p->iHead == p->iTail );
+ Sat_ManEnqueue( p, pVar, Value );
+}
+
+/**Function*************************************************************
+
+ Synopsis [Propagates one assignment.]
+
+ Description [Returns 1 if there is no conflict, 0 otherwise.]
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+static inline int Sat_ManPropagateOne( Sat_Man_t * p, int iPos )
+{
+ Gia_Obj_t * pVar, * pFan0, * pFan1;
+ pVar = Gia_ManObj( p->pGia, p->pTrail[iPos] );
+ if ( Gia_ObjIsCi(pVar) )
+ return 1;
+ pFan0 = Gia_ObjFanin0(pVar);
+ pFan1 = Gia_ObjFanin1(pVar);
+ if ( Sat_VarValue(pVar) ) // positive
+ {
+ if ( Sat_VarIsAssigned(pFan0) )
+ {
+ if ( Sat_VarValue(pFan0) == Gia_ObjFaninC0(pVar) ) // negative -> conflict
+ return 0;
+ // check second var
+ if ( Sat_VarIsAssigned(pFan1) )
+ {
+ if ( Sat_VarValue(pFan1) == Gia_ObjFaninC1(pVar) ) // negative -> conflict
+ return 0;
+ // positive + positive -> nothing to do
+ return 1;
+ }
+ }
+ else
+ {
+ // pFan0 unassigned -> enqueue first var
+ Sat_ManEnqueue( p, pFan0, !Gia_ObjFaninC0(pVar) );
+ // check second var
+ if ( Sat_VarIsAssigned(pFan1) )
+ {
+ if ( Sat_VarValue(pFan1) == Gia_ObjFaninC1(pVar) ) // negative -> conflict
+ return 0;
+ // positive + positive -> nothing to do
+ return 1;
+ }
+ }
+ // unassigned -> enqueue second var
+ Sat_ManEnqueue( p, pFan1, !Gia_ObjFaninC1(pVar) );
+ }
+ else // negative
+ {
+ if ( Sat_VarIsAssigned(pFan0) )
+ {
+ if ( Sat_VarValue(pFan0) == Gia_ObjFaninC0(pVar) ) // negative -> nothing to do
+ return 1;
+ if ( Sat_VarIsAssigned(pFan1) )
+ {
+ if ( Sat_VarValue(pFan1) == Gia_ObjFaninC1(pVar) ) // negative -> nothing to do
+ return 1;
+ // positive + positive -> conflict
+ return 0;
+ }
+ // positive + unassigned -> enqueue second var
+ Sat_ManEnqueue( p, pFan1, Gia_ObjFaninC1(pVar) );
+ }
+ else
+ {
+ if ( Sat_VarIsAssigned(pFan1) )
+ {
+ if ( Sat_VarValue(pFan1) == Gia_ObjFaninC1(pVar) ) // negative -> nothing to do
+ return 1;
+ // unassigned + positive -> enqueue first var
+ Sat_ManEnqueue( p, pFan0, Gia_ObjFaninC0(pVar) );
+ }
+ }
+ }
+ return 1;
+}
+
+/**Function*************************************************************
+
+ Synopsis [Propagates assignments.]
+
+ Description [Returns 1 if there is no conflict.]
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+static inline int Sat_ManPropagate( Sat_Man_t * p )
+{
+ assert( p->iHead <= p->iTail );
+ for ( ; p->iHead < p->iTail; p->iHead++ )
+ if ( !Sat_ManPropagateOne( p, p->pTrail[p->iHead] ) )
+ return 0;
+ return 1;
+}
+
+/**Function*************************************************************
+
+ Synopsis [Propagates one assignment.]
+
+ Description [Returns 1 if justified, 0 if conflict, -1 if needs justification.]
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+static inline int Sat_ManJustifyNextOne( Sat_Man_t * p, int iPos )
+{
+ Gia_Obj_t * pVar, * pFan0, * pFan1;
+ pVar = Gia_ManObj( p->pGia, p->pTrail[iPos] );
+ if ( Gia_ObjIsCi(pVar) )
+ return 1;
+ pFan0 = Gia_ObjFanin0(pVar);
+ pFan1 = Gia_ObjFanin1(pVar);
+ if ( Sat_VarValue(pVar) ) // positive
+ return 1;
+ // nevative
+ if ( Sat_VarIsAssigned(pFan0) )
+ {
+ if ( Sat_VarValue(pFan0) == Gia_ObjFaninC0(pVar) ) // negative -> already justified
+ return 1;
+ // positive
+ if ( Sat_VarIsAssigned(pFan1) )
+ {
+ if ( Sat_VarValue(pFan1) == Gia_ObjFaninC1(pVar) ) // negative -> already justified
+ return 1;
+ // positive -> conflict
+ return 0;
+ }
+ // unasigned -> propagate
+ Sat_ManAssume( p, pFan1, Gia_ObjFaninC1(pVar) );
+ return Sat_ManPropagate(p);
+ }
+ if ( Sat_VarIsAssigned(pFan1) )
+ {
+ if ( Sat_VarValue(pFan1) == Gia_ObjFaninC1(pVar) ) // negative -> already justified
+ return 1;
+ // positive
+ assert( !Sat_VarIsAssigned(pFan0) );
+ // unasigned -> propagate
+ Sat_ManAssume( p, pFan0, Gia_ObjFaninC0(pVar) );
+ return Sat_ManPropagate(p);
+ }
+ return -1;
+}
+
+/**Function*************************************************************
+
+ Synopsis [Justifies assignments.]
+
+ Description [Returns 1 for UNSAT, 0 for SAT, -1 for UNDECIDED.]
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+int Sat_ManJustify( Sat_Man_t * p )
+{
+ Gia_Obj_t * pVar, * pFan0, * pFan1;
+ int RetValue, iState, iJustState;
+ if ( p->nConfs && p->nConfs >= p->nConfsMax )
+ return -1;
+ // get the next variable to justify
+ assert( p->iJust <= p->iTail );
+ iJustState = p->iJust;
+ for ( ; p->iJust < p->iTail; p->iJust++ )
+ {
+ RetValue = Sat_ManJustifyNextOne( p, p->pTrail[p->iJust] );
+ if ( RetValue == 0 )
+ return 1;
+ if ( RetValue == -1 )
+ break;
+ }
+ if ( p->iJust == p->iTail ) // could not find
+ return 0;
+ // found variable to justify
+ pVar = Gia_ManObj( p->pGia, p->pTrail[p->iJust] );
+ pFan0 = Gia_ObjFanin0(pVar);
+ pFan1 = Gia_ObjFanin1(pVar);
+ assert( !Sat_VarValue(pVar) && !Sat_VarIsAssigned(pFan0) && !Sat_VarIsAssigned(pFan1) );
+ // remember the state of the stack
+ iState = p->iHead;
+ // try to justify by setting first fanin to 0
+ Sat_ManAssume( p, pFan0, Gia_ObjFaninC0(pVar) );
+ if ( Sat_ManPropagate(p) )
+ {
+ RetValue = Sat_ManJustify(p);
+ if ( RetValue != 1 )
+ return RetValue;
+ }
+ Sat_ManCancelUntil( p, iState );
+ // try to justify by setting second fanin to 0
+ Sat_ManAssume( p, pFan1, Gia_ObjFaninC1(pVar) );
+ if ( Sat_ManPropagate(p) )
+ {
+ RetValue = Sat_ManJustify(p);
+ if ( RetValue != 1 )
+ return RetValue;
+ }
+ Sat_ManCancelUntil( p, iState );
+ p->iJust = iJustState;
+ p->nConfs++;
+ return 1;
+}
+
+/**Function*************************************************************
+
+ Synopsis [Runs one call to the SAT solver.]
+
+ Description [Returns 1 for UNSAT, 0 for SAT, -1 for UNDECIDED.]
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+int Sat_ManPrepare( Sat_Man_t * p, int * pLits, int nLits, int nConfsMax )
+{
+ Gia_Obj_t * pVar;
+ int i;
+ // double check that vars are unassigned
+ Gia_ManForEachObj( p->pGia, pVar, i )
+ assert( !Sat_VarIsAssigned(pVar) );
+ // prepare
+ p->iHead = p->iTail = p->iJust = 0;
+ p->nConfsMax = nConfsMax;
+ // assign literals
+ for ( i = 0; i < nLits; i++ )
+ {
+ pVar = Gia_ManObj( p->pGia, Gia_Lit2Var(pLits[i]) );
+ if ( Sat_VarIsAssigned(pVar) ) // assigned
+ {
+ if ( Sat_VarValue(pVar) != Gia_LitIsCompl(pLits[i]) ) // compatible assignment
+ continue;
+ }
+ else // unassigned
+ {
+ Sat_ManAssume( p, pVar, !Gia_LitIsCompl(pLits[i]) );
+ if ( Sat_ManPropagate(p) )
+ continue;
+ }
+ // conflict
+ Sat_ManCancelUntil( p, 0 );
+ return 1;
+ }
+ assert( p->iHead == p->iTail );
+ return 0;
+}
+
+
+/**Function*************************************************************
+
+ Synopsis [Runs one call to the SAT solver.]
+
+ Description [Returns 1 for UNSAT, 0 for SAT, -1 for UNDECIDED.]
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+int Sat_ManSolve( Sat_Man_t * p, int * pLits, int nLits, int nConfsMax )
+{
+ int RetValue;
+ // propagate the assignments
+ if ( Sat_ManPrepare( p, pLits, nLits, nConfsMax ) )
+ return 1;
+ // justify the assignments
+ RetValue = Sat_ManJustify( p );
+ if ( RetValue == 0 ) // SAT
+ Sat_ManDeriveModel( p );
+ // return the solver to the initial state
+ Sat_ManCancelUntil( p, 0 );
+ return RetValue;
+}
+
+/**Function*************************************************************
+
+ Synopsis [Testing the SAT solver.]
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+int Sat_ManTest( Gia_Man_t * pGia, Gia_Obj_t * pObj, int nConfsMax )
+{
+ Sat_Man_t * p;
+ int RetValue, iLit;
+ assert( Gia_ObjIsCo(pObj) );
+ p = Sat_ManCreate( pGia );
+ iLit = Gia_LitNot( Gia_ObjFaninLit0p(pGia, pObj) );
+ RetValue = Sat_ManSolve( p, &iLit, 1, nConfsMax );
+ if ( RetValue == 0 )
+ {
+ Cec_ManPatVerifyPattern( pGia, pObj, p->vModel );
+ Cec_ManPatCleanMark0( pGia, pObj );
+ }
+ Sat_ManDelete( p );
+ return RetValue;
+}
+
+////////////////////////////////////////////////////////////////////////
+/// END OF FILE ///
+////////////////////////////////////////////////////////////////////////
+
+
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