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Diffstat (limited to 'src/proof/fraig/fraigCanon.c')
| -rw-r--r-- | src/proof/fraig/fraigCanon.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/src/proof/fraig/fraigCanon.c b/src/proof/fraig/fraigCanon.c new file mode 100644 index 00000000..47539db2 --- /dev/null +++ b/src/proof/fraig/fraigCanon.c @@ -0,0 +1,223 @@ +/**CFile**************************************************************** + + FileName [fraigCanon.c] + + PackageName [FRAIG: Functionally reduced AND-INV graphs.] + + Synopsis [AND-node creation and elementary AND-operation.] + + Author [Alan Mishchenko <alanmi@eecs.berkeley.edu>] + + Affiliation [UC Berkeley] + + Date [Ver. 2.0. Started - October 1, 2004] + + Revision [$Id: fraigCanon.c,v 1.4 2005/07/08 01:01:31 alanmi Exp $] + +***********************************************************************/ + +#include <limits.h> +#include "fraigInt.h" + +ABC_NAMESPACE_IMPL_START + + +//////////////////////////////////////////////////////////////////////// +/// DECLARATIONS /// +//////////////////////////////////////////////////////////////////////// + +//////////////////////////////////////////////////////////////////////// +/// FUNCTION DEFINITIONS /// +//////////////////////////////////////////////////////////////////////// + +/**Function************************************************************* + + Synopsis [The internal AND operation for the two FRAIG nodes.] + + Description [This procedure is the core of the FRAIG package, because + it performs the two-step canonicization of FRAIG nodes. The first step + involves the lookup in the structural hash table (which hashes two ANDs + into a node that has them as fanins, if such a node exists). If the node + is not found in the structural hash table, an attempt is made to find a + functionally equivalent node in another hash table (which hashes the + simulation info into the nodes, which has this simulation info). Some + tricks used on the way are described in the comments to the code and + in the paper "FRAIGs: Functionally reduced AND-INV graphs".] + + SideEffects [] + + SeeAlso [] + +***********************************************************************/ +Fraig_Node_t * Fraig_NodeAndCanon( Fraig_Man_t * pMan, Fraig_Node_t * p1, Fraig_Node_t * p2 ) +{ + Fraig_Node_t * pNodeNew, * pNodeOld, * pNodeRepr; + int fUseSatCheck; +// int RetValue; + + // check for trivial cases + if ( p1 == p2 ) + return p1; + if ( p1 == Fraig_Not(p2) ) + return Fraig_Not(pMan->pConst1); + if ( Fraig_NodeIsConst(p1) ) + { + if ( p1 == pMan->pConst1 ) + return p2; + return Fraig_Not(pMan->pConst1); + } + if ( Fraig_NodeIsConst(p2) ) + { + if ( p2 == pMan->pConst1 ) + return p1; + return Fraig_Not(pMan->pConst1); + } +/* + // check for less trivial cases + if ( Fraig_IsComplement(p1) ) + { + if ( RetValue = Fraig_NodeIsInSupergate( Fraig_Regular(p1), p2 ) ) + { + if ( RetValue == -1 ) + pMan->nImplies0++; + else + pMan->nImplies1++; + + if ( RetValue == -1 ) + return p2; + } + } + else + { + if ( RetValue = Fraig_NodeIsInSupergate( p1, p2 ) ) + { + if ( RetValue == 1 ) + pMan->nSimplifies1++; + else + pMan->nSimplifies0++; + + if ( RetValue == 1 ) + return p1; + return Fraig_Not(pMan->pConst1); + } + } + + if ( Fraig_IsComplement(p2) ) + { + if ( RetValue = Fraig_NodeIsInSupergate( Fraig_Regular(p2), p1 ) ) + { + if ( RetValue == -1 ) + pMan->nImplies0++; + else + pMan->nImplies1++; + + if ( RetValue == -1 ) + return p1; + } + } + else + { + if ( RetValue = Fraig_NodeIsInSupergate( p2, p1 ) ) + { + if ( RetValue == 1 ) + pMan->nSimplifies1++; + else + pMan->nSimplifies0++; + + if ( RetValue == 1 ) + return p2; + return Fraig_Not(pMan->pConst1); + } + } +*/ + // perform level-one structural hashing + if ( Fraig_HashTableLookupS( pMan, p1, p2, &pNodeNew ) ) // the node with these children is found + { + // if the existent node is part of the cone of unused logic + // (that is logic feeding the node which is equivalent to the given node) + // return the canonical representative of this node + // determine the phase of the given node, with respect to its canonical form + pNodeRepr = Fraig_Regular(pNodeNew)->pRepr; + if ( pMan->fFuncRed && pNodeRepr ) + return Fraig_NotCond( pNodeRepr, Fraig_IsComplement(pNodeNew) ^ Fraig_NodeComparePhase(Fraig_Regular(pNodeNew), pNodeRepr) ); + // otherwise, the node is itself a canonical representative, return it + return pNodeNew; + } + // the same node is not found, but the new one is created + + // if one level hashing is requested (without functionality hashing), return + if ( !pMan->fFuncRed ) + return pNodeNew; + + // check if the new node is unique using the simulation info + if ( pNodeNew->nOnes == 0 || pNodeNew->nOnes == (unsigned)pMan->nWordsRand * 32 ) + { + pMan->nSatZeros++; + if ( !pMan->fDoSparse ) // if we do not do sparse functions, skip + return pNodeNew; + // check the sparse function simulation hash table + pNodeOld = Fraig_HashTableLookupF0( pMan, pNodeNew ); + if ( pNodeOld == NULL ) // the node is unique (it is added to the table) + return pNodeNew; + } + else + { + // check the simulation hash table + pNodeOld = Fraig_HashTableLookupF( pMan, pNodeNew ); + if ( pNodeOld == NULL ) // the node is unique + return pNodeNew; + } + assert( pNodeOld->pRepr == 0 ); + // there is another node which looks the same according to simulation + + // use SAT to resolve the ambiguity + fUseSatCheck = (pMan->nInspLimit == 0 || Fraig_ManReadInspects(pMan) < pMan->nInspLimit); + if ( fUseSatCheck && Fraig_NodeIsEquivalent( pMan, pNodeOld, pNodeNew, pMan->nBTLimit, 1000000 ) ) + { + // set the node to be equivalent with this node + // to prevent loops, only set if the old node is not in the TFI of the new node + // the loop may happen in the following case: suppose + // NodeC = AND(NodeA, NodeB) and at the same time NodeA => NodeB + // in this case, NodeA and NodeC are functionally equivalent + // however, NodeA is a fanin of node NodeC (this leads to the loop) + // add the node to the list of equivalent nodes or dereference it + if ( pMan->fChoicing && !Fraig_CheckTfi( pMan, pNodeOld, pNodeNew ) ) + { + // if the old node is not in the TFI of the new node and choicing + // is enabled, add the new node to the list of equivalent ones + pNodeNew->pNextE = pNodeOld->pNextE; + pNodeOld->pNextE = pNodeNew; + } + // set the canonical representative of this node + pNodeNew->pRepr = pNodeOld; + // return the equivalent node + return Fraig_NotCond( pNodeOld, Fraig_NodeComparePhase(pNodeOld, pNodeNew) ); + } + + // now we add another member to this simulation class + if ( pNodeNew->nOnes == 0 || pNodeNew->nOnes == (unsigned)pMan->nWordsRand * 32 ) + { + Fraig_Node_t * pNodeTemp; + assert( pMan->fDoSparse ); + pNodeTemp = Fraig_HashTableLookupF0( pMan, pNodeNew ); +// assert( pNodeTemp == NULL ); +// Fraig_HashTableInsertF0( pMan, pNodeNew ); + } + else + { + pNodeNew->pNextD = pNodeOld->pNextD; + pNodeOld->pNextD = pNodeNew; + } + // return the new node + assert( pNodeNew->pRepr == 0 ); + return pNodeNew; +} + + +//////////////////////////////////////////////////////////////////////// +/// END OF FILE /// +//////////////////////////////////////////////////////////////////////// + + +ABC_NAMESPACE_IMPL_END + |