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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 ///
////////////////////////////////////////////////////////////////////////
|
