/**CFile**************************************************************** FileName [darCut.c] SystemName [ABC: Logic synthesis and verification system.] PackageName [DAG-aware AIG rewriting.] Synopsis [Computation of 4-input cuts.] Author [Alan Mishchenko] Affiliation [UC Berkeley] Date [Ver. 1.0. Started - April 28, 2007.] Revision [$Id: darCut.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $] ***********************************************************************/ #include "darInt.h" ABC_NAMESPACE_IMPL_START //////////////////////////////////////////////////////////////////////// /// DECLARATIONS /// //////////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////// /// FUNCTION DEFINITIONS /// //////////////////////////////////////////////////////////////////////// /**Function************************************************************* Synopsis [Prints one cut.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ void Dar_CutPrint( Dar_Cut_t * pCut ) { unsigned i; printf( "{" ); for ( i = 0; i < pCut->nLeaves; i++ ) printf( " %d", pCut->pLeaves[i] ); printf( " }\n" ); } /**Function************************************************************* Synopsis [Prints one cut.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ void Dar_ObjCutPrint( Aig_Man_t * p, Aig_Obj_t * pObj ) { Dar_Cut_t * pCut; int i; printf( "Cuts for node %d:\n", pObj->Id ); Dar_ObjForEachCut( pObj, pCut, i ) Dar_CutPrint( pCut ); // printf( "\n" ); } /**Function************************************************************* Synopsis [Returns the number of 1s in the machine word.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline int Dar_WordCountOnes( unsigned uWord ) { uWord = (uWord & 0x55555555) + ((uWord>>1) & 0x55555555); uWord = (uWord & 0x33333333) + ((uWord>>2) & 0x33333333); uWord = (uWord & 0x0F0F0F0F) + ((uWord>>4) & 0x0F0F0F0F); uWord = (uWord & 0x00FF00FF) + ((uWord>>8) & 0x00FF00FF); return (uWord & 0x0000FFFF) + (uWord>>16); } /**Function************************************************************* Synopsis [Compute the cost of the cut.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline int Dar_CutFindValue( Dar_Man_t * p, Dar_Cut_t * pCut ) { Aig_Obj_t * pLeaf; int i, Value, nOnes; assert( pCut->fUsed ); Value = 0; nOnes = 0; Dar_CutForEachLeaf( p->pAig, pCut, pLeaf, i ) { if ( pLeaf == NULL ) return 0; assert( pLeaf != NULL ); Value += pLeaf->nRefs; nOnes += (pLeaf->nRefs == 1); } if ( pCut->nLeaves < 2 ) return 1001; // Value = Value * 100 / pCut->nLeaves; if ( Value > 1000 ) Value = 1000; if ( nOnes > 3 ) Value = 5 - nOnes; return Value; } /**Function************************************************************* Synopsis [Returns the next free cut to use.] Description [Uses the cut with the smallest value.] SideEffects [] SeeAlso [] ***********************************************************************/ static inline Dar_Cut_t * Dar_CutFindFree( Dar_Man_t * p, Aig_Obj_t * pObj ) { Dar_Cut_t * pCut, * pCutMax; int i; pCutMax = NULL; Dar_ObjForEachCutAll( pObj, pCut, i ) { if ( pCut->fUsed == 0 ) return pCut; if ( pCut->nLeaves < 3 ) continue; if ( pCutMax == NULL || pCutMax->Value > pCut->Value ) pCutMax = pCut; } if ( pCutMax == NULL ) { Dar_ObjForEachCutAll( pObj, pCut, i ) { if ( pCut->nLeaves < 2 ) continue; if ( pCutMax == NULL || pCutMax->Value > pCut->Value ) pCutMax = pCut; } } if ( pCutMax == NULL ) { Dar_ObjForEachCutAll( pObj, pCut, i ) { if ( pCutMax == NULL || pCutMax->Value > pCut->Value ) pCutMax = pCut; } } assert( pCutMax != NULL ); pCutMax->fUsed = 0; return pCutMax; } /**Function************************************************************* Synopsis [Returns 1 if pDom is contained in pCut.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline int Dar_CutCheckDominance( Dar_Cut_t * pDom, Dar_Cut_t * pCut ) { int i, k; assert( pDom->fUsed && pCut->fUsed ); for ( i = 0; i < (int)pDom->nLeaves; i++ ) { for ( k = 0; k < (int)pCut->nLeaves; k++ ) if ( pDom->pLeaves[i] == pCut->pLeaves[k] ) break; if ( k == (int)pCut->nLeaves ) // node i in pDom is not contained in pCut return 0; } // every node in pDom is contained in pCut return 1; } /**Function************************************************************* Synopsis [Returns 1 if the cut is contained.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline int Dar_CutFilter( Aig_Obj_t * pObj, Dar_Cut_t * pCut ) { Dar_Cut_t * pTemp; int i; assert( pCut->fUsed ); // go through the cuts of the node Dar_ObjForEachCut( pObj, pTemp, i ) { if ( pTemp == pCut ) continue; if ( pTemp->nLeaves > pCut->nLeaves ) { // skip the non-contained cuts if ( (pTemp->uSign & pCut->uSign) != pCut->uSign ) continue; // check containment seriously if ( Dar_CutCheckDominance( pCut, pTemp ) ) { // remove contained cut pTemp->fUsed = 0; } } else { // skip the non-contained cuts if ( (pTemp->uSign & pCut->uSign) != pTemp->uSign ) continue; // check containment seriously if ( Dar_CutCheckDominance( pTemp, pCut ) ) { // remove the given cut pCut->fUsed = 0; return 1; } } } return 0; } /**Function************************************************************* Synopsis [Merges two cuts.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline int Dar_CutMergeOrdered( Dar_Cut_t * pC, Dar_Cut_t * pC0, Dar_Cut_t * pC1 ) { int i, k, c; assert( pC0->nLeaves >= pC1->nLeaves ); // the case of the largest cut sizes if ( pC0->nLeaves == 4 && pC1->nLeaves == 4 ) { if ( pC0->uSign != pC1->uSign ) return 0; for ( i = 0; i < (int)pC0->nLeaves; i++ ) if ( pC0->pLeaves[i] != pC1->pLeaves[i] ) return 0; for ( i = 0; i < (int)pC0->nLeaves; i++ ) pC->pLeaves[i] = pC0->pLeaves[i]; pC->nLeaves = pC0->nLeaves; return 1; } // the case when one of the cuts is the largest if ( pC0->nLeaves == 4 ) { if ( (pC0->uSign & pC1->uSign) != pC1->uSign ) return 0; for ( i = 0; i < (int)pC1->nLeaves; i++ ) { for ( k = (int)pC0->nLeaves - 1; k >= 0; k-- ) if ( pC0->pLeaves[k] == pC1->pLeaves[i] ) break; if ( k == -1 ) // did not find return 0; } for ( i = 0; i < (int)pC0->nLeaves; i++ ) pC->pLeaves[i] = pC0->pLeaves[i]; pC->nLeaves = pC0->nLeaves; return 1; } // compare two cuts with different numbers i = k = 0; for ( c = 0; c < 4; c++ ) { if ( k == (int)pC1->nLeaves ) { if ( i == (int)pC0->nLeaves ) { pC->nLeaves = c; return 1; } pC->pLeaves[c] = pC0->pLeaves[i++]; continue; } if ( i == (int)pC0->nLeaves ) { if ( k == (int)pC1->nLeaves ) { pC->nLeaves = c; return 1; } pC->pLeaves[c] = pC1->pLeaves[k++]; continue; } if ( pC0->pLeaves[i] < pC1->pLeaves[k] ) { pC->pLeaves[c] = pC0->pLeaves[i++]; continue; } if ( pC0->pLeaves[i] > pC1->pLeaves[k] ) { pC->pLeaves[c] = pC1->pLeaves[k++]; continue; } pC->pLeaves[c] = pC0->pLeaves[i++]; k++; } if ( i < (int)pC0->nLeaves || k < (int)pC1->nLeaves ) return 0; pC->nLeaves = c; return 1; } /**Function************************************************************* Synopsis [Prepares the object for FPGA mapping.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline int Dar_CutMerge( Dar_Cut_t * pCut, Dar_Cut_t * pCut0, Dar_Cut_t * pCut1 ) { assert( !pCut->fUsed ); // merge the nodes if ( pCut0->nLeaves <= pCut1->nLeaves ) { if ( !Dar_CutMergeOrdered( pCut, pCut1, pCut0 ) ) return 0; } else { if ( !Dar_CutMergeOrdered( pCut, pCut0, pCut1 ) ) return 0; } pCut->uSign = pCut0->uSign | pCut1->uSign; pCut->fUsed = 1; return 1; } /**Function************************************************************* Synopsis [Computes the stretching phase of the cut w.r.t. the merged cut.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline unsigned Dar_CutTruthPhase( Dar_Cut_t * pCut, Dar_Cut_t * pCut1 ) { unsigned uPhase = 0; int i, k; for ( i = k = 0; i < (int)pCut->nLeaves; i++ ) { if ( k == (int)pCut1->nLeaves ) break; if ( pCut->pLeaves[i] < pCut1->pLeaves[k] ) continue; assert( pCut->pLeaves[i] == pCut1->pLeaves[k] ); uPhase |= (1 << i); k++; } return uPhase; } /**Function************************************************************* Synopsis [Swaps two advancent variables of the truth table.] Description [Swaps variable iVar and iVar+1.] SideEffects [] SeeAlso [] ***********************************************************************/ static inline unsigned Dar_CutTruthSwapAdjacentVars( unsigned uTruth, int iVar ) { assert( iVar >= 0 && iVar <= 2 ); if ( iVar == 0 ) return (uTruth & 0x99999999) | ((uTruth & 0x22222222) << 1) | ((uTruth & 0x44444444) >> 1); if ( iVar == 1 ) return (uTruth & 0xC3C3C3C3) | ((uTruth & 0x0C0C0C0C) << 2) | ((uTruth & 0x30303030) >> 2); if ( iVar == 2 ) return (uTruth & 0xF00FF00F) | ((uTruth & 0x00F000F0) << 4) | ((uTruth & 0x0F000F00) >> 4); assert( 0 ); return 0; } /**Function************************************************************* Synopsis [Swaps polarity of the variable.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline unsigned Dar_CutTruthSwapPolarity( unsigned uTruth, int iVar ) { assert( iVar >= 0 && iVar <= 3 ); if ( iVar == 0 ) return ((uTruth & 0xAAAA) >> 1) | ((uTruth & 0x5555) << 1); if ( iVar == 1 ) return ((uTruth & 0xCCCC) >> 2) | ((uTruth & 0x3333) << 2); if ( iVar == 2 ) return ((uTruth & 0xF0F0) >> 4) | ((uTruth & 0x0F0F) << 4); if ( iVar == 3 ) return ((uTruth & 0xFF00) >> 8) | ((uTruth & 0x00FF) << 8); assert( 0 ); return 0; } /**Function************************************************************* Synopsis [Expands the truth table according to the phase.] Description [The input and output truth tables are in pIn/pOut. The current number of variables is nVars. The total number of variables in nVarsAll. The last argument (Phase) contains shows where the variables should go.] SideEffects [] SeeAlso [] ***********************************************************************/ static inline unsigned Dar_CutTruthStretch( unsigned uTruth, int nVars, unsigned Phase ) { int i, k, Var = nVars - 1; for ( i = 3; i >= 0; i-- ) if ( Phase & (1 << i) ) { for ( k = Var; k < i; k++ ) uTruth = Dar_CutTruthSwapAdjacentVars( uTruth, k ); Var--; } assert( Var == -1 ); return uTruth; } /**Function************************************************************* Synopsis [Shrinks the truth table according to the phase.] Description [The input and output truth tables are in pIn/pOut. The current number of variables is nVars. The total number of variables in nVarsAll. The last argument (Phase) contains shows what variables should remain.] SideEffects [] SeeAlso [] ***********************************************************************/ static inline unsigned Dar_CutTruthShrink( unsigned uTruth, int nVars, unsigned Phase ) { int i, k, Var = 0; for ( i = 0; i < 4; i++ ) if ( Phase & (1 << i) ) { for ( k = i-1; k >= Var; k-- ) uTruth = Dar_CutTruthSwapAdjacentVars( uTruth, k ); Var++; } return uTruth; } /**Function************************************************************* Synopsis [Sort variables by their ID.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ unsigned Dar_CutSortVars( unsigned uTruth, int * pVars ) { int i, Temp, fChange, Counter = 0; // replace -1 by large number for ( i = 0; i < 4; i++ ) { if ( pVars[i] == -1 ) pVars[i] = 0x3FFFFFFF; else if ( Abc_LitIsCompl(pVars[i]) ) { pVars[i] = Abc_LitNot( pVars[i] ); uTruth = Dar_CutTruthSwapPolarity( uTruth, i ); } } // permute variables do { fChange = 0; for ( i = 0; i < 3; i++ ) { if ( pVars[i] <= pVars[i+1] ) continue; Counter++; fChange = 1; Temp = pVars[i]; pVars[i] = pVars[i+1]; pVars[i+1] = Temp; uTruth = Dar_CutTruthSwapAdjacentVars( uTruth, i ); } } while ( fChange ); // replace large number by -1 for ( i = 0; i < 4; i++ ) { if ( pVars[i] == 0x3FFFFFFF ) pVars[i] = -1; // printf( "%d ", pVars[i] ); } // printf( "\n" ); return uTruth; } /**Function************************************************************* Synopsis [Performs truth table computation.] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ static inline unsigned Dar_CutTruth( Dar_Cut_t * pCut, Dar_Cut_t * pCut0, Dar_Cut_t * pCut1, int fCompl0, int fCompl1 ) { unsigned uTruth0 = fCompl0 ? ~pCut0->uTruth : pCut0->uTruth; unsigned uTruth1 = fCompl1 ? ~pCut1->uTruth : pCut1->uTruth; uTruth0 = Dar_CutTruthStretch( uTruth0, pCut0->nLeaves, Dar_CutTruthPhase(pCut, pCut0) ); uTruth1 = Dar_CutTruthStretch( uTruth1, pCut1->nLeaves, Dar_CutTruthPhase(pCut, pCut1) ); return uTruth0 & uTruth1; } /**Function************************************************************* Synopsis [Minimize support of the cut.] Description [Returns 1 if the node's support has changed] SideEffects [] SeeAlso [] ***********************************************************************/ static inline int Dar_CutSuppMinimize( Dar_Cut_t * pCut ) { unsigned uMasks[4][2] = { { 0x5555, 0xAAAA }, { 0x3333, 0xCCCC }, { 0x0F0F, 0xF0F0 }, { 0x00FF, 0xFF00 } }; unsigned uPhase = 0, uTruth = 0xFFFF & pCut->uTruth; int i, k, nLeaves; assert( pCut->fUsed ); // compute the support of the cut's function nLeaves = pCut->nLeaves; for ( i = 0; i < (int)pCut->nLeaves; i++ ) if ( (uTruth & uMasks[i][0]) == ((uTruth & uMasks[i][1]) >> (1 << i)) ) nLeaves--; else uPhase |= (1 << i); if ( nLeaves == (int)pCut->nLeaves ) return 0; // shrink the truth table uTruth = Dar_CutTruthShrink( uTruth, pCut->nLeaves, uPhase ); pCut->uTruth = 0xFFFF & uTruth; // update leaves and signature pCut->uSign = 0; for ( i = k = 0; i < (int)pCut->nLeaves; i++ ) { if ( !(uPhase & (1 << i)) ) continue; pCut->pLeaves[k++] = pCut->pLeaves[i]; pCut->uSign |= Aig_ObjCutSign( pCut->pLeaves[i] ); } assert( k == nLeaves ); pCut->nLeaves = nLeaves; return 1; } /**Function************************************************************* Synopsis [] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ void Dar_ManCutsFree( Dar_Man_t * p ) { if ( p->pMemCuts == NULL ) return; Aig_MmFixedStop( p->pMemCuts, 0 ); p->pMemCuts = NULL; // Aig_ManCleanData( p ); } /**Function************************************************************* Synopsis [] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ Dar_Cut_t * Dar_ObjPrepareCuts( Dar_Man_t * p, Aig_Obj_t * pObj ) { Dar_Cut_t * pCutSet, * pCut; int i; assert( Dar_ObjCuts(pObj) == NULL ); pObj->nCuts = p->pPars->nCutsMax; // create the cutset of the node pCutSet = (Dar_Cut_t *)Aig_MmFixedEntryFetch( p->pMemCuts ); memset( pCutSet, 0, p->pPars->nCutsMax * sizeof(Dar_Cut_t) ); Dar_ObjSetCuts( pObj, pCutSet ); Dar_ObjForEachCutAll( pObj, pCut, i ) pCut->fUsed = 0; Vec_PtrPush( p->vCutNodes, pObj ); // add unit cut if needed pCut = pCutSet; pCut->fUsed = 1; if ( Aig_ObjIsConst1(pObj) ) { pCut->nLeaves = 0; pCut->uSign = 0; pCut->uTruth = 0xFFFF; } else { pCut->nLeaves = 1; pCut->pLeaves[0] = pObj->Id; pCut->uSign = Aig_ObjCutSign( pObj->Id ); pCut->uTruth = 0xAAAA; } pCut->Value = Dar_CutFindValue( p, pCut ); if ( p->nCutMemUsed < Aig_MmFixedReadMemUsage(p->pMemCuts)/(1<<20) ) p->nCutMemUsed = Aig_MmFixedReadMemUsage(p->pMemCuts)/(1<<20); return pCutSet; } /**Function************************************************************* Synopsis [] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ void Dar_ManCutsRestart( Dar_Man_t * p, Aig_Obj_t * pRoot ) { Aig_Obj_t * pObj; int i; Dar_ObjSetCuts( Aig_ManConst1(p->pAig), NULL ); Vec_PtrForEachEntry( Aig_Obj_t *, p->vCutNodes, pObj, i ) if ( !Aig_ObjIsNone(pObj) ) Dar_ObjSetCuts( pObj, NULL ); Vec_PtrClear( p->vCutNodes ); Aig_MmFixedRestart( p->pMemCuts ); Dar_ObjPrepareCuts( p, Aig_ManConst1(p->pAig) ); } /**Function************************************************************* Synopsis [] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ Dar_Cut_t * Dar_ObjComputeCuts( Dar_Man_t * p, Aig_Obj_t * pObj, int fSkipTtMin ) { Aig_Obj_t * pFanin0 = Aig_ObjReal_rec( Aig_ObjChild0(pObj) ); Aig_Obj_t * pFanin1 = Aig_ObjReal_rec( Aig_ObjChild1(pObj) ); Aig_Obj_t * pFaninR0 = Aig_Regular(pFanin0); Aig_Obj_t * pFaninR1 = Aig_Regular(pFanin1); Dar_Cut_t * pCutSet, * pCut0, * pCut1, * pCut; int i, k; assert( !Aig_IsComplement(pObj) ); assert( Aig_ObjIsNode(pObj) ); assert( Dar_ObjCuts(pObj) == NULL ); assert( Dar_ObjCuts(pFaninR0) != NULL ); assert( Dar_ObjCuts(pFaninR1) != NULL ); // set up the first cut pCutSet = Dar_ObjPrepareCuts( p, pObj ); // make sure fanins cuts are computed Dar_ObjForEachCut( pFaninR0, pCut0, i ) Dar_ObjForEachCut( pFaninR1, pCut1, k ) { p->nCutsAll++; // make sure K-feasible cut exists if ( Dar_WordCountOnes(pCut0->uSign | pCut1->uSign) > 4 ) continue; // get the next cut of this node pCut = Dar_CutFindFree( p, pObj ); // create the new cut if ( !Dar_CutMerge( pCut, pCut0, pCut1 ) ) { assert( !pCut->fUsed ); continue; } p->nCutsTried++; // check dominance if ( Dar_CutFilter( pObj, pCut ) ) { assert( !pCut->fUsed ); continue; } // compute truth table pCut->uTruth = 0xFFFF & Dar_CutTruth( pCut, pCut0, pCut1, Aig_IsComplement(pFanin0), Aig_IsComplement(pFanin1) ); // minimize support of the cut if ( !fSkipTtMin && Dar_CutSuppMinimize( pCut ) ) { int RetValue = Dar_CutFilter( pObj, pCut ); assert( !RetValue ); } // assign the value of the cut pCut->Value = Dar_CutFindValue( p, pCut ); // if the cut contains removed node, do not use it if ( pCut->Value == 0 ) { p->nCutsSkipped++; pCut->fUsed = 0; } else if ( pCut->nLeaves < 2 ) return pCutSet; } // count the number of nontrivial cuts cuts Dar_ObjForEachCut( pObj, pCut, i ) p->nCutsUsed += pCut->fUsed; // discount trivial cut p->nCutsUsed--; return pCutSet; } /**Function************************************************************* Synopsis [] Description [] SideEffects [] SeeAlso [] ***********************************************************************/ Dar_Cut_t * Dar_ObjComputeCuts_rec( Dar_Man_t * p, Aig_Obj_t * pObj ) { if ( Dar_ObjCuts(pObj) ) return Dar_ObjCuts(pObj); if ( Aig_ObjIsCi(pObj) ) return Dar_ObjPrepareCuts( p, pObj ); if ( Aig_ObjIsBuf(pObj) ) return Dar_ObjComputeCuts_rec( p, Aig_ObjFanin0(pObj) ); Dar_ObjComputeCuts_rec( p, Aig_ObjFanin0(pObj) ); Dar_ObjComputeCuts_rec( p, Aig_ObjFanin1(pObj) ); return Dar_ObjComputeCuts( p, pObj, 0 ); } //////////////////////////////////////////////////////////////////////// /// END OF FILE /// //////////////////////////////////////////////////////////////////////// ABC_NAMESPACE_IMPL_END