/**CFile**************************************************************** FileName [hopBalance.c] SystemName [ABC: Logic synthesis and verification system.] PackageName [Minimalistic And-Inverter Graph package.] Synopsis [Algebraic AIG balancing.] Author [Alan Mishchenko] Affiliation [UC Berkeley] Date [Ver. 1.0. Started - May 11, 2006.] Revision [\$Id: hopBalance.c,v 1.00 2006/05/11 00:00:00 alanmi Exp \$] ***********************************************************************/ #include "hop.h" ABC_NAMESPACE_IMPL_START //////////////////////////////////////////////////////////////////////// /// DECLARATIONS /// //////////////////////////////////////////////////////////////////////// static Hop_Obj_t * Hop_NodeBalance_rec( Hop_Man_t * pNew, Hop_Obj_t * pObj, Vec_Vec_t * vStore, int Level, int fUpdateLevel ); static Vec_Ptr_t * Hop_NodeBalanceCone( Hop_Obj_t * pObj, Vec_Vec_t * vStore, int Level ); static int Hop_NodeBalanceFindLeft( Vec_Ptr_t * vSuper ); static void Hop_NodeBalancePermute( Hop_Man_t * p, Vec_Ptr_t * vSuper, int LeftBound, int fExor ); static void Hop_NodeBalancePushUniqueOrderByLevel( Vec_Ptr_t * vStore, Hop_Obj_t * pObj ); //////////////////////////////////////////////////////////////////////// /// FUNCTION DEFINITIONS /// //////////////////////////////////////////////////////////////////////// /**Function************************************************************* Synopsis [Performs algebraic balancing of the AIG.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ Hop_Man_t * Hop_ManBalance( Hop_Man_t * p, int fUpdateLevel ) { Hop_Man_t * pNew; Hop_Obj_t * pObj, * pObjNew; Vec_Vec_t * vStore; int i; // create the new manager pNew = Hop_ManStart(); pNew->fRefCount = 0; // map the PI nodes Hop_ManCleanData( p ); Hop_ManConst1(p)->pData = Hop_ManConst1(pNew); Hop_ManForEachPi( p, pObj, i ) pObj->pData = Hop_ObjCreatePi(pNew); // balance the AIG vStore = Vec_VecAlloc( 50 ); Hop_ManForEachPo( p, pObj, i ) { pObjNew = Hop_NodeBalance_rec( pNew, Hop_ObjFanin0(pObj), vStore, 0, fUpdateLevel ); Hop_ObjCreatePo( pNew, Hop_NotCond( pObjNew, Hop_ObjFaninC0(pObj) ) ); } Vec_VecFree( vStore ); // remove dangling nodes // Hop_ManCreateRefs( pNew ); // if ( i = Hop_ManCleanup( pNew ) ) // printf( "Cleanup after balancing removed %d dangling nodes.\n", i ); // check the resulting AIG if ( !Hop_ManCheck(pNew) ) printf( "Hop_ManBalance(): The check has failed.\n" ); return pNew; } /**Function************************************************************* Synopsis [Returns the new node constructed.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ Hop_Obj_t * Hop_NodeBalance_rec( Hop_Man_t * pNew, Hop_Obj_t * pObjOld, Vec_Vec_t * vStore, int Level, int fUpdateLevel ) { Hop_Obj_t * pObjNew; Vec_Ptr_t * vSuper; int i; assert( !Hop_IsComplement(pObjOld) ); // return if the result is known if ( pObjOld->pData ) return (Hop_Obj_t *)pObjOld->pData; assert( Hop_ObjIsNode(pObjOld) ); // get the implication supergate vSuper = Hop_NodeBalanceCone( pObjOld, vStore, Level ); // check if supergate contains two nodes in the opposite polarity if ( vSuper->nSize == 0 ) return (Hop_Obj_t *)(pObjOld->pData = Hop_ManConst0(pNew)); if ( Vec_PtrSize(vSuper) < 2 ) printf( "BUG!\n" ); // for each old node, derive the new well-balanced node for ( i = 0; i < Vec_PtrSize(vSuper); i++ ) { pObjNew = Hop_NodeBalance_rec( pNew, Hop_Regular((Hop_Obj_t *)vSuper->pArray[i]), vStore, Level + 1, fUpdateLevel ); vSuper->pArray[i] = Hop_NotCond( pObjNew, Hop_IsComplement((Hop_Obj_t *)vSuper->pArray[i]) ); } // build the supergate pObjNew = Hop_NodeBalanceBuildSuper( pNew, vSuper, Hop_ObjType(pObjOld), fUpdateLevel ); // make sure the balanced node is not assigned // assert( pObjOld->Level >= Hop_Regular(pObjNew)->Level ); assert( pObjOld->pData == NULL ); return (Hop_Obj_t *)(pObjOld->pData = pObjNew); } /**Function************************************************************* Synopsis [Collects the nodes of the supergate.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ int Hop_NodeBalanceCone_rec( Hop_Obj_t * pRoot, Hop_Obj_t * pObj, Vec_Ptr_t * vSuper ) { int RetValue1, RetValue2, i; // check if the node is visited if ( Hop_Regular(pObj)->fMarkB ) { // check if the node occurs in the same polarity for ( i = 0; i < vSuper->nSize; i++ ) if ( vSuper->pArray[i] == pObj ) return 1; // check if the node is present in the opposite polarity for ( i = 0; i < vSuper->nSize; i++ ) if ( vSuper->pArray[i] == Hop_Not(pObj) ) return -1; assert( 0 ); return 0; } // if the new node is complemented or a PI, another gate begins if ( pObj != pRoot && (Hop_IsComplement(pObj) || Hop_ObjType(pObj) != Hop_ObjType(pRoot) || Hop_ObjRefs(pObj) > 1 || Vec_PtrSize(vSuper) > 10000) ) { Vec_PtrPush( vSuper, pObj ); Hop_Regular(pObj)->fMarkB = 1; return 0; } assert( !Hop_IsComplement(pObj) ); assert( Hop_ObjIsNode(pObj) ); // go through the branches RetValue1 = Hop_NodeBalanceCone_rec( pRoot, Hop_ObjChild0(pObj), vSuper ); RetValue2 = Hop_NodeBalanceCone_rec( pRoot, Hop_ObjChild1(pObj), vSuper ); if ( RetValue1 == -1 || RetValue2 == -1 ) return -1; // return 1 if at least one branch has a duplicate return RetValue1 || RetValue2; } /**Function************************************************************* Synopsis [Collects the nodes of the supergate.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ Vec_Ptr_t * Hop_NodeBalanceCone( Hop_Obj_t * pObj, Vec_Vec_t * vStore, int Level ) { Vec_Ptr_t * vNodes; int RetValue, i; assert( !Hop_IsComplement(pObj) ); // extend the storage if ( Vec_VecSize( vStore ) <= Level ) Vec_VecPush( vStore, Level, 0 ); // get the temporary array of nodes vNodes = Vec_VecEntry( vStore, Level ); Vec_PtrClear( vNodes ); // collect the nodes in the implication supergate RetValue = Hop_NodeBalanceCone_rec( pObj, pObj, vNodes ); assert( vNodes->nSize > 1 ); // unmark the visited nodes Vec_PtrForEachEntry( Hop_Obj_t *, vNodes, pObj, i ) Hop_Regular(pObj)->fMarkB = 0; // if we found the node and its complement in the same implication supergate, // return empty set of nodes (meaning that we should use constant-0 node) if ( RetValue == -1 ) vNodes->nSize = 0; return vNodes; } /**Function************************************************************* Synopsis [Procedure used for sorting the nodes in decreasing order of levels.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ int Hop_NodeCompareLevelsDecrease( Hop_Obj_t ** pp1, Hop_Obj_t ** pp2 ) { int Diff = Hop_ObjLevel(Hop_Regular(*pp1)) - Hop_ObjLevel(Hop_Regular(*pp2)); if ( Diff > 0 ) return -1; if ( Diff < 0 ) return 1; Diff = Hop_Regular(*pp1)->Id - Hop_Regular(*pp2)->Id; if ( Diff > 0 ) return -1; if ( Diff < 0 ) return 1; return 0; } /**Function************************************************************* Synopsis [Builds implication supergate.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ Hop_Obj_t * Hop_NodeBalanceBuildSuper( Hop_Man_t * p, Vec_Ptr_t * vSuper, Hop_Type_t Type, int fUpdateLevel ) { Hop_Obj_t * pObj1, * pObj2; int LeftBound; assert( vSuper->nSize > 1 ); // sort the new nodes by level in the decreasing order Vec_PtrSort( vSuper, (int (*)(void))Hop_NodeCompareLevelsDecrease ); // balance the nodes while ( vSuper->nSize > 1 ) { // find the left bound on the node to be paired LeftBound = (!fUpdateLevel)? 0 : Hop_NodeBalanceFindLeft( vSuper ); // find the node that can be shared (if no such node, randomize choice) Hop_NodeBalancePermute( p, vSuper, LeftBound, Type == AIG_EXOR ); // pull out the last two nodes pObj1 = (Hop_Obj_t *)Vec_PtrPop(vSuper); pObj2 = (Hop_Obj_t *)Vec_PtrPop(vSuper); Hop_NodeBalancePushUniqueOrderByLevel( vSuper, Hop_Oper(p, pObj1, pObj2, Type) ); } return (Hop_Obj_t *)Vec_PtrEntry(vSuper, 0); } /**Function************************************************************* Synopsis [Finds the left bound on the next candidate to be paired.] Description [The nodes in the array are in the decreasing order of levels. The last node in the array has the smallest level. By default it would be paired with the next node on the left. However, it may be possible to pair it with some other node on the left, in such a way that the new node is shared. This procedure finds the index of the left-most node, which can be paired with the last node.] SideEffects [] SeeAlso [] ***********************************************************************/ int Hop_NodeBalanceFindLeft( Vec_Ptr_t * vSuper ) { Hop_Obj_t * pObjRight, * pObjLeft; int Current; // if two or less nodes, pair with the first if ( Vec_PtrSize(vSuper) < 3 ) return 0; // set the pointer to the one before the last Current = Vec_PtrSize(vSuper) - 2; pObjRight = (Hop_Obj_t *)Vec_PtrEntry( vSuper, Current ); // go through the nodes to the left of this one for ( Current--; Current >= 0; Current-- ) { // get the next node on the left pObjLeft = (Hop_Obj_t *)Vec_PtrEntry( vSuper, Current ); // if the level of this node is different, quit the loop if ( Hop_ObjLevel(Hop_Regular(pObjLeft)) != Hop_ObjLevel(Hop_Regular(pObjRight)) ) break; } Current++; // get the node, for which the equality holds pObjLeft = (Hop_Obj_t *)Vec_PtrEntry( vSuper, Current ); assert( Hop_ObjLevel(Hop_Regular(pObjLeft)) == Hop_ObjLevel(Hop_Regular(pObjRight)) ); return Current; } /**Function************************************************************* Synopsis [Moves closer to the end the node that is best for sharing.] Description [If there is no node with sharing, randomly chooses one of the legal nodes.] SideEffects [] SeeAlso [] ***********************************************************************/ void Hop_NodeBalancePermute( Hop_Man_t * p, Vec_Ptr_t * vSuper, int LeftBound, int fExor ) { Hop_Obj_t * pObj1, * pObj2, * pObj3, * pGhost; int RightBound, i; // get the right bound RightBound = Vec_PtrSize(vSuper) - 2; assert( LeftBound <= RightBound ); if ( LeftBound == RightBound ) return; // get the two last nodes pObj1 = (Hop_Obj_t *)Vec_PtrEntry( vSuper, RightBound + 1 ); pObj2 = (Hop_Obj_t *)Vec_PtrEntry( vSuper, RightBound ); if ( Hop_Regular(pObj1) == p->pConst1 || Hop_Regular(pObj2) == p->pConst1 ) return; // find the first node that can be shared for ( i = RightBound; i >= LeftBound; i-- ) { pObj3 = (Hop_Obj_t *)Vec_PtrEntry( vSuper, i ); if ( Hop_Regular(pObj3) == p->pConst1 ) { Vec_PtrWriteEntry( vSuper, i, pObj2 ); Vec_PtrWriteEntry( vSuper, RightBound, pObj3 ); return; } pGhost = Hop_ObjCreateGhost( p, pObj1, pObj3, fExor? AIG_EXOR : AIG_AND ); if ( Hop_TableLookup( p, pGhost ) ) { if ( pObj3 == pObj2 ) return; Vec_PtrWriteEntry( vSuper, i, pObj2 ); Vec_PtrWriteEntry( vSuper, RightBound, pObj3 ); return; } } /* // we did not find the node to share, randomize choice { int Choice = rand() % (RightBound - LeftBound + 1); pObj3 = Vec_PtrEntry( vSuper, LeftBound + Choice ); if ( pObj3 == pObj2 ) return; Vec_PtrWriteEntry( vSuper, LeftBound + Choice, pObj2 ); Vec_PtrWriteEntry( vSuper, RightBound, pObj3 ); } */ } /**Function************************************************************* Synopsis [Inserts a new node in the order by levels.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ void Hop_NodeBalancePushUniqueOrderByLevel( Vec_Ptr_t * vStore, Hop_Obj_t * pObj ) { Hop_Obj_t * pObj1, * pObj2; int i; if ( Vec_PtrPushUnique(vStore, pObj) ) return; // find the p of the node for ( i = vStore->nSize-1; i > 0; i-- ) { pObj1 = (Hop_Obj_t *)vStore->pArray[i ]; pObj2 = (Hop_Obj_t *)vStore->pArray[i-1]; if ( Hop_ObjLevel(Hop_Regular(pObj1)) <= Hop_ObjLevel(Hop_Regular(pObj2)) ) break; vStore->pArray[i ] = pObj2; vStore->pArray[i-1] = pObj1; } } //////////////////////////////////////////////////////////////////////// /// END OF FILE /// //////////////////////////////////////////////////////////////////////// ABC_NAMESPACE_IMPL_END