Version abc50817

7 files changed, 1778 insertions, 0 deletions

diff --git a/src/opt/rwr/rwr.h b/src/opt/rwr/rwr.h
new file mode 100644
index 00000000..19fc34c4
--- /dev/null
+++ b/src/opt/rwr/rwr.h
@@ -0,0 +1,131 @@
+/**CFile****************************************************************
+
+  FileName    [rwr.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwr.h,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __RWR_H__
+#define __RWR_H__
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include "abc.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+ 
+#define RWR_LIMIT  1048576/4  // ((1 << 20) 
+
+typedef struct Rwr_Node_t_  Rwr_Node_t;
+struct Rwr_Node_t_ // 24 bytes
+{
+    int                Id;               // ID 
+    int                TravId;           // traversal ID
+    unsigned           uTruth : 16;      // truth table
+    unsigned           Volume :  8;      // volume
+    unsigned           Level  :  5;      // level
+    unsigned           fMark  :  1;      // mark
+    unsigned           fUsed  :  1;      // mark
+    unsigned           fExor  :  1;      // mark
+    Rwr_Node_t *       p0;               // first child
+    Rwr_Node_t *       p1;               // second child
+    Rwr_Node_t *       pNext;            // next in the table
+};
+
+typedef struct Rwr_Cut_t_  Rwr_Cut_t;
+struct Rwr_Cut_t_ // 24 bytes
+{
+    unsigned           nLeaves : 3;      // the number of leaves
+    unsigned           fTime  :  1;      // set to 1 if meets the required times
+    unsigned           fGain  :  1;      // set to 1 if does not increase nodes
+    unsigned           Volume : 11;      // the gain in the number of nodes
+    unsigned           uTruth : 16;      // the truth table
+    Abc_Obj_t *        ppLeaves[4];      // the leaves
+    Rwr_Cut_t *        pNext;            // the next cut in the list
+};
+
+struct Abc_ManRwr_t_
+{
+    // internal lookups
+    int                nFuncs;           // the number of four var functions
+    unsigned short *   puCanons;         // canonical forms
+    char *             puPhases;         // canonical phases
+    char *             pPractical;       // practical classes
+    unsigned short     puPerms[256][16]; // permutations for three var functions
+    // node space
+    Vec_Ptr_t *        vForest;          // all the nodes
+    Rwr_Node_t **      pTable;           // the hash table of nodes by their canonical form
+    Extra_MmFixed_t *  pMmNode;          // memory for nodes and cuts
+    int                nTravIds;         // the counter of traversal IDs
+    int                nConsidered;      // the number of nodes considered
+    int                nAdded;           // the number of nodes added to lists
+    int                nClasses;         // the number of NN classes
+    // intermediate data
+    Vec_Int_t *        vFanNums;         // the number of fanouts of each node (used to free cuts)
+    Vec_Int_t *        vReqTimes;        // the required times for each node (used for delay-driven evalution)
+    // the result of resynthesis
+    Vec_Int_t *        vForm;            // the decomposition tree (temporary)
+    Vec_Ptr_t *        vFanins;          // the fanins array (temporary)
+    Vec_Ptr_t *        vTfo;             // the TFO node array (temporary)
+    Vec_Vec_t *        vLevels;          // the levelized structure (temporary)
+    int                nGainMax;
+    // runtime statistics
+    int                time1;
+    int                time2;
+    int                time3;
+    int                time4;
+};
+
+// manipulation of complemented attributes
+static inline bool         Rwr_IsComplement( Rwr_Node_t * p )    { return (bool)(((unsigned)p) & 01);           }
+static inline Rwr_Node_t * Rwr_Regular( Rwr_Node_t * p )         { return (Rwr_Node_t *)((unsigned)(p) & ~01);  }
+static inline Rwr_Node_t * Rwr_Not( Rwr_Node_t * p )             { return (Rwr_Node_t *)((unsigned)(p) ^  01);  }
+static inline Rwr_Node_t * Rwr_NotCond( Rwr_Node_t * p, int c )  { return (Rwr_Node_t *)((unsigned)(p) ^ (c));  }
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFITIONS                             ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== rwrLib.c ==========================================================*/
+extern void                Rwr_ManPrecompute( Abc_ManRwr_t * p );
+extern void                Rwr_ManWriteToFile( Abc_ManRwr_t * p, char * pFileName );
+extern void                Rwr_ManLoadFromFile( Abc_ManRwr_t * p, char * pFileName );
+extern void                Rwr_ManPrint( Abc_ManRwr_t * p );
+extern Rwr_Node_t *        Rwr_ManAddVar( Abc_ManRwr_t * p, unsigned uTruth );
+/*=== rwrMan.c ==========================================================*/
+extern unsigned short      Rwr_FunctionPhase( unsigned uTruth, unsigned uPhase );
+/*=== rwrUtil.c ==========================================================*/
+extern Vec_Int_t *         Rwt_NtkFanoutCounters( Abc_Ntk_t * pNtk );
+extern Vec_Int_t *         Rwt_NtkRequiredLevels( Abc_Ntk_t * pNtk );
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+#endif
+
diff --git a/src/opt/rwr/rwrCut.c b/src/opt/rwr/rwrCut.c
new file mode 100644
index 00000000..88ea3cdb
--- /dev/null
+++ b/src/opt/rwr/rwrCut.c
@@ -0,0 +1,256 @@
+/**CFile****************************************************************
+
+  FileName    [rwrCut.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Cut computation.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrCut.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static Rwr_Cut_t * Rwr_CutAlloc( Abc_ManRwr_t * p );
+static Rwr_Cut_t * Rwr_CutCreateTriv( Abc_ManRwr_t * p, Abc_Obj_t * pNode );
+static Rwr_Cut_t * Rwr_CutsMerge( Abc_ManRwr_t * p, Rwr_Cut_t * pCut0, Rwr_Cut_t * pCut1, int fCompl0, int fCompl1 );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns elementary cuts to the PIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkManRwrStartCuts( Abc_ManRwr_t * p, Abc_Ntk_t * pNtk )
+{
+    Abc_Obj_t * pNode;
+    int i;
+    // set the trivial cuts
+    Abc_NtkCleanCopy( pNtk );
+    Abc_NtkForEachCi( pNtk, pNode, i )
+        pNode->pCopy = (Abc_Obj_t *)Rwr_CutCreateTriv( p, pNode );
+    // precompute the required times for all internal nodes
+    p->vFanNums = Rwt_NtkFanoutCounters( pNtk );
+    // save the fanout counters for all internal nodes
+    p->vReqTimes = Rwt_NtkRequiredLevels( pNtk );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes cuts for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NodeRwrComputeCuts( Abc_ManRwr_t * p, Abc_Obj_t * pNode )
+{
+    Rwr_Cut_t * pCuts0, * pCuts1, * pTemp0, * pTemp1, * pCut;
+    Rwr_Cut_t * pList = NULL, ** ppPlace = &pList; // linked list of cuts
+    assert( Abc_ObjIsNode(pNode) );
+    if ( Abc_NodeIsConst(pNode) )
+        return;
+    // create the elementary cut
+    pCut = Rwr_CutCreateTriv( p, pNode );
+    // add it to the linked list
+    *ppPlace = pCut;  ppPlace  = &pCut->pNext;
+    // create cuts by merging pairwise
+    pCuts0 = (Rwr_Cut_t *)Abc_ObjFanin0(pNode)->pCopy;
+    pCuts1 = (Rwr_Cut_t *)Abc_ObjFanin1(pNode)->pCopy;
+    assert( pCuts0 && pCuts1 );
+    for ( pTemp0 = pCuts0; pTemp0; pTemp0 = pTemp0->pNext )
+    for ( pTemp1 = pCuts1; pTemp1; pTemp1 = pTemp1->pNext )
+    {
+        pCut = Rwr_CutsMerge( p, pTemp0, pTemp1, Abc_ObjFaninC0(pNode), Abc_ObjFaninC1(pNode) );
+        if ( pCut == NULL )
+            continue;
+        // add it to the linked list
+        *ppPlace = pCut;  ppPlace  = &pCut->pNext;
+    }
+    // set the linked list
+    pNode->pCopy = (Abc_Obj_t *)pList;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Start the cut computation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Cut_t * Rwr_CutsMerge( Abc_ManRwr_t * p, Rwr_Cut_t * pCut0, Rwr_Cut_t * pCut1, int fCompl0, int fCompl1 )
+{
+    Abc_Obj_t * ppNodes[4], * pNodeTemp;
+    Rwr_Cut_t * pCut;
+    unsigned uPhase, uTruth0, uTruth1;
+    int i, k, min, nTotal;
+
+    // solve the most typical case: both cuts are four input
+    if ( pCut0->nLeaves == 4 && pCut1->nLeaves == 4 )
+    {
+        for ( i = 0; i < 4; i++ )
+            if ( pCut0->ppLeaves[i] != pCut1->ppLeaves[i] )
+                return NULL;
+        // create the cut
+        pCut = Rwr_CutAlloc( p );
+        pCut->nLeaves = 4;
+        for ( i = 0; i < 4; i++ )
+            pCut->ppLeaves[i] = pCut0->ppLeaves[i];
+        pCut->uTruth = (fCompl0? ~pCut0->uTruth : pCut0->uTruth) & (fCompl1? ~pCut1->uTruth : pCut1->uTruth) & 0xFFFF;
+        return pCut;
+    }
+
+    // create the set of new nodes
+    // count the number of unique entries in pCut1
+    nTotal = pCut0->nLeaves;
+    for ( i = 0; i < (int)pCut1->nLeaves; i++ )
+    {
+        // try to find this entry among the leaves of pCut0
+        for ( k = 0; k < (int)pCut0->nLeaves; k++ )
+            if ( pCut1->ppLeaves[i] == pCut0->ppLeaves[k] )
+                break;
+        if ( k < (int)pCut0->nLeaves ) // found
+            continue;
+        // we found a new entry to add
+        if ( nTotal == 4 )
+            return NULL;
+        ppNodes[nTotal++] = pCut1->ppLeaves[i];
+    }
+    // we know that the feasible cut exists
+
+    // add the starting entries
+    for ( k = 0; k < (int)pCut0->nLeaves; k++ )
+        ppNodes[k] = pCut0->ppLeaves[k];
+
+    // selection-sort the entries
+    for ( i = 0; i < nTotal - 1; i++ )
+    {
+        min = i;
+        for ( k = i+1; k < nTotal; k++ )
+            if ( ppNodes[k]->Id < ppNodes[min]->Id )
+                min = k;
+        pNodeTemp    = ppNodes[i];
+        ppNodes[i]   = ppNodes[min];
+        ppNodes[min] = pNodeTemp;
+    }
+
+    // find the mapping from the old nodes to the new
+    if ( pCut0->nLeaves == 4 )
+        uTruth0 = pCut0->uTruth;
+    else
+    {
+        uPhase = 0;
+        for ( i = 0; i < (int)pCut0->nLeaves; i++ )
+        {
+            for ( k = 0; k < nTotal; k++ )
+                if ( pCut0->ppLeaves[i] == ppNodes[k] )
+                    break;
+            uPhase |= (1 << k);
+        }
+        assert( uPhase < 16 );
+        assert( pCut0->uTruth < 256 );
+        uTruth0 = p->puPerms[pCut0->uTruth][uPhase];
+    }
+
+    // find the mapping from the old nodes to the new
+    if ( pCut1->nLeaves == 4 )
+        uTruth1 = pCut1->uTruth;
+    else
+    {
+        uPhase = 0;
+        for ( i = 0; i < (int)pCut1->nLeaves; i++ )
+        {
+            for ( k = 0; k < nTotal; k++ )
+                if ( pCut1->ppLeaves[i] == ppNodes[k] )
+                    break;
+            uPhase |= (1 << k);
+        }
+        assert( uPhase < 16 );
+        assert( pCut1->uTruth < 256 );
+        uTruth1 = p->puPerms[pCut1->uTruth][uPhase];
+    }
+
+    // create the cut
+    pCut = Rwr_CutAlloc( p );
+    pCut->nLeaves = nTotal;
+    for ( i = 0; i < nTotal; i++ )
+        pCut->ppLeaves[i] = ppNodes[i];
+    pCut->uTruth = (fCompl0? ~uTruth0 : uTruth0) & (fCompl1? ~uTruth1 : uTruth1) & 0xFFFF;
+    return pCut;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Start the cut computation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Cut_t * Rwr_CutAlloc( Abc_ManRwr_t * p )
+{
+    Rwr_Cut_t * pCut;
+    pCut = (Rwr_Cut_t *)Extra_MmFixedEntryFetch( p->pMmNode );
+    memset( pCut, 0, sizeof(Rwr_Cut_t) );
+    return pCut;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Start the cut computation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Cut_t * Rwr_CutCreateTriv( Abc_ManRwr_t * p, Abc_Obj_t * pNode )
+{
+    Rwr_Cut_t * pCut;
+    pCut = Rwr_CutAlloc( p );
+    pCut->nLeaves = 1;
+    pCut->ppLeaves[0] = pNode;
+    pCut->uTruth = 0xAAAA;
+    return pCut;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrEva.c b/src/opt/rwr/rwrEva.c
new file mode 100644
index 00000000..ecf03f4f
--- /dev/null
+++ b/src/opt/rwr/rwrEva.c
@@ -0,0 +1,129 @@
+/**CFile****************************************************************
+
+  FileName    [rwrDec.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Evaluation and decomposition procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrDec.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Rwr_CutEvaluate( Abc_ManRwr_t * p, Rwr_Cut_t * pCut );
+static void Rwr_CutDecompose( Abc_ManRwr_t * p, Rwr_Cut_t * pCut, Vec_Int_t * vForm );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs rewriting for one node.]
+
+  Description [This procedure considers all the cuts computed for the node
+  and tries to rewrite each of them using the "forest" of different AIG
+  structures precomputed and stored in the RWR manager. 
+  Determines the best rewriting and computes the gain in the number of AIG
+  nodes in the final network. In the end, p->vFanins contains information 
+  about the best cut that can be used for rewriting, while p->vForm gives 
+  the decomposition tree (represented using factored form data structure).
+  Returns gain in the number of nodes or -1 if node cannot be rewritten.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NodeRwrRewrite( Abc_ManRwr_t * p, Abc_Obj_t * pNode )
+{
+    Vec_Ptr_t Vector = {0,0,0}, * vFanins = &Vector;
+    Rwr_Cut_t * pCut, * pCutBest;
+    int BestGain = -1;
+    int i, Required = Vec_IntEntry( p->vReqTimes, pNode->Id );
+
+    // go through the cuts
+    for ( pCut = (Rwr_Cut_t *)pNode->pCopy, pCut = pCut->pNext; pCut; pCut = pCut->pNext )
+    {
+        // collect the TFO
+        vFanins->nSize  = pCut->nLeaves;
+        vFanins->pArray = pCut->ppLeaves;
+        Abc_NodeCollectTfoCands( pNode->pNtk, pNode, vFanins, Required, p->vLevels, p->vTfo );
+        // evaluate the cut
+        Rwr_CutEvaluate( p, pCut );
+        // check if the cut is the best
+        if ( pCut->fTime && pCut->fGain )
+        {
+            pCutBest = pCut;
+            BestGain = pCut->Volume;
+        }
+    }
+    if ( BestGain == -1 )
+        return -1;
+    // we found a good cut
+
+    // prepare the fanins
+    Vec_PtrClear( p->vFanins );
+    for ( i = 0; i < (int)pCutBest->nLeaves; i++ )
+        Vec_PtrPush( p->vFanins, pCutBest->ppLeaves[i] );
+    // collect the TFO again
+    Abc_NodeCollectTfoCands( pNode->pNtk, pNode, p->vFanins, Required, p->vLevels, p->vTfo );
+    // perform the decomposition
+    Rwr_CutDecompose( p, pCutBest, p->vForm );
+    // the best fanins are in p->vFanins, the result of decomposition is in p->vForm
+    return BestGain;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Evaluates one cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_CutEvaluate( Abc_ManRwr_t * p, Rwr_Cut_t * pCut )
+{
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Evaluates one cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_CutDecompose( Abc_ManRwr_t * p, Rwr_Cut_t * pCut, Vec_Int_t * vForm )
+{
+}
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrExp.c b/src/opt/rwr/rwrExp.c
new file mode 100644
index 00000000..37eabf5b
--- /dev/null
+++ b/src/opt/rwr/rwrExp.c
@@ -0,0 +1,179 @@
+/**CFile****************************************************************
+
+  FileName    [rwrExp.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Computation of practically used NN-classes of 4-input cuts.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrExp.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Abc_ManRwrExp_t_ Abc_ManRwrExp_t;
+struct Abc_ManRwrExp_t_
+{
+    // internal lookups
+    int                nFuncs;           // the number of four-var functions
+    unsigned short *   puCanons;         // canonical forms
+    int *              pnCounts;         // the counters of functions in each class
+    int                nConsidered;      // the number of nodes considered
+    int                nClasses;         // the number of NN classes
+};
+
+static Abc_ManRwrExp_t * s_pManRwrExp = NULL;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_ManExploreStart()
+{
+    Abc_ManRwrExp_t * p;
+    unsigned uTruth;
+    int i, k, nClasses;
+    int clk = clock();
+
+    p = ALLOC( Abc_ManRwrExp_t, 1 );
+    memset( p, 0, sizeof(Abc_ManRwrExp_t) );
+    // canonical forms
+    p->nFuncs    = (1<<16);
+    p->puCanons  = ALLOC( unsigned short, p->nFuncs );
+    memset( p->puCanons, 0, sizeof(unsigned short) * p->nFuncs );
+    // counters
+    p->pnCounts  = ALLOC( int, p->nFuncs );
+    memset( p->pnCounts, 0, sizeof(int) * p->nFuncs );
+
+    // initialize the canonical forms
+    nClasses = 1;
+    for ( i = 1; i < p->nFuncs-1; i++ )
+    {
+        if ( p->puCanons[i] )
+            continue;
+        nClasses++;
+        for ( k = 0; k < 32; k++ )
+        {
+            uTruth = Rwr_FunctionPhase( (unsigned)i, (unsigned)k );
+            if ( p->puCanons[uTruth] == 0 )
+                p->puCanons[uTruth] = (unsigned short)i;
+            else
+                assert( p->puCanons[uTruth] == (unsigned short)i );
+        }
+    }
+    // set info for constant 1
+    p->puCanons[p->nFuncs-1] = 0;
+    printf( "The number of NN-canonical forms = %d.\n", nClasses );
+    s_pManRwrExp = p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_ManExploreCount( unsigned uTruth )
+{
+    assert( uTruth < (1<<16) );
+    s_pManRwrExp->pnCounts[ s_pManRwrExp->puCanons[uTruth] ]++;    
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_ManExplorePrint()
+{
+    FILE * pFile;
+    int i, CountMax, CountWrite, nCuts, nClasses;
+    int * pDistrib;
+    int * pReprs;
+    // find the max number of occurences
+    nCuts = nClasses = 0;
+    CountMax = 0;
+    for ( i = 0; i < s_pManRwrExp->nFuncs; i++ )
+    {
+        if ( CountMax < s_pManRwrExp->pnCounts[i] )
+            CountMax = s_pManRwrExp->pnCounts[i];
+        nCuts += s_pManRwrExp->pnCounts[i];
+        if ( s_pManRwrExp->pnCounts[i] > 0 )
+            nClasses++;
+    }
+    printf( "Number of cuts considered       = %8d.\n", nCuts );
+    printf( "Classes occurring at least once = %8d.\n", nClasses );
+    // print the distribution of classes
+    pDistrib = ALLOC( int, CountMax + 1 );
+    pReprs   = ALLOC( int, CountMax + 1 );
+    memset( pDistrib, 0, sizeof(int)*(CountMax + 1) );
+    for ( i = 0; i < s_pManRwrExp->nFuncs; i++ )
+    {
+        pDistrib[ s_pManRwrExp->pnCounts[i] ]++;
+        pReprs[ s_pManRwrExp->pnCounts[i] ] = i;
+    }
+
+    printf( "Occurence = %6d.  Num classes = %4d.  \n", 0, 2288-nClasses );
+    for ( i = 1; i <= CountMax; i++ )
+        if ( pDistrib[i] )
+        {
+            printf( "Occurence = %6d.  Num classes = %4d.  Repr = ", i, pDistrib[i] );
+            Extra_PrintBinary( stdout, (unsigned*)&(pReprs[i]), 16 ); 
+            printf( "\n" );
+        }
+    free( pDistrib );
+    free( pReprs );
+    // write into a file all classes above limit (5)
+    CountWrite = 0;
+    pFile = fopen( "nnclass_stats.txt", "w" );
+    for ( i = 0; i < s_pManRwrExp->nFuncs; i++ )
+        if ( s_pManRwrExp->pnCounts[i] > 5 )
+        {
+            fprintf( pFile, "%d ", i );
+            CountWrite++;
+        }
+    fclose( pFile );
+    printf( "%d classes written into file \"%s\".\n", CountWrite, "nnclass_stats.txt" );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrLib.c b/src/opt/rwr/rwrLib.c
new file mode 100644
index 00000000..91604244
--- /dev/null
+++ b/src/opt/rwr/rwrLib.c
@@ -0,0 +1,670 @@
+/**CFile****************************************************************
+
+  FileName    [rwrLib.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrLib.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static Rwr_Node_t *        Rwr_ManTryNode( Abc_ManRwr_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1, int fExor, int Level, int Volume );
+static Rwr_Node_t *        Rwr_ManAddNode( Abc_ManRwr_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1, int fExor, int Level, int Volume );
+static int                 Rwr_ManNodeVolume( Abc_ManRwr_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1 );
+
+static void                Rwr_ManIncTravId_int( Abc_ManRwr_t * p );
+static inline void         Rwr_ManIncTravId( Abc_ManRwr_t * p )     { if ( p->nTravIds++ == 0x8FFFFFFF ) Rwr_ManIncTravId_int( p ); }
+
+static void                Rwr_MarkUsed_rec( Abc_ManRwr_t * p, Rwr_Node_t * pNode );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Precomputes the forest in the manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManPrecompute( Abc_ManRwr_t * p )
+{
+    Rwr_Node_t * p0, * p1;
+    int i, k, Level, Volume;
+    int LevelOld = -1;
+    int nNodes;
+
+    Vec_PtrForEachEntryStart( p->vForest, p0, i, 1 )
+    Vec_PtrForEachEntryStart( p->vForest, p1, k, 1 )
+    {
+        if ( LevelOld < (int)p0->Level )
+        {
+            LevelOld = p0->Level;
+            printf( "Starting level %d  (at %d nodes).\n", LevelOld+1, i );
+            printf( "Considered = %5d M.   Found = %8d.   Classes = %6d.   Trying %7d.\n", 
+                p->nConsidered/1000000, p->vForest->nSize, p->nClasses, i );
+        }
+
+        if ( k == i )
+            break;
+//        if ( p0->Level + p1->Level > 6 ) // hard
+//            break;
+
+        if ( p0->Level + p1->Level > 5 ) // easy 
+            break;
+
+//        if ( p0->Level + p1->Level > 6 || (p0->Level == 3 && p1->Level == 3) )
+//            break;
+
+        // compute the level and volume of the new nodes
+        Level  = 1 + ABC_MAX( p0->Level, p1->Level );
+        Volume = 1 + Rwr_ManNodeVolume( p, p0, p1 );
+        // try four different nodes
+        Rwr_ManTryNode( p,         p0 ,         p1 , 0, Level, Volume );
+        Rwr_ManTryNode( p, Rwr_Not(p0),         p1 , 0, Level, Volume );
+        Rwr_ManTryNode( p,         p0 , Rwr_Not(p1), 0, Level, Volume );
+        Rwr_ManTryNode( p, Rwr_Not(p0), Rwr_Not(p1), 0, Level, Volume );
+        // try EXOR
+        Rwr_ManTryNode( p,         p0 ,         p1 , 1, Level, Volume + 1 );
+        // report the progress
+        if ( p->nConsidered % 50000000 == 0 )
+            printf( "Considered = %5d M.   Found = %8d.   Classes = %6d.   Trying %7d.\n", 
+                p->nConsidered/1000000, p->vForest->nSize, p->nClasses, i );
+        // quit after some time
+        if ( p->vForest->nSize == RWR_LIMIT + 5 )
+        {
+            printf( "Considered = %5d M.   Found = %8d.   Classes = %6d.   Trying %7d.\n", 
+                p->nConsidered/1000000, p->vForest->nSize, p->nClasses, i );
+            goto save;
+        }
+    }
+save :
+
+    // mark the relevant ones
+    Rwr_ManIncTravId( p );
+    k = 5;
+    nNodes = 0;
+    Vec_PtrForEachEntryStart( p->vForest, p0, i, 5 )
+        if ( p0->uTruth == p->puCanons[p0->uTruth] )
+        {
+            Rwr_MarkUsed_rec( p, p0 );
+            nNodes++;
+        }
+
+    // compact the array by throwing away non-canonical
+    k = 5;
+    Vec_PtrForEachEntryStart( p->vForest, p0, i, 5 )
+        if ( p0->fUsed )
+        {
+            p->vForest->pArray[k] = p0;
+            p0->Id = k;
+            k++;
+        }
+    p->vForest->nSize = k;
+    printf( "Total canonical = %4d. Total used = %5d.\n", nNodes, p->vForest->nSize );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Writes to file.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManWriteToFile( Abc_ManRwr_t * p, char * pFileName )
+{
+    FILE * pFile;
+    Rwr_Node_t * pNode;
+    unsigned * pBuffer;
+    int i, nEntries, clk = clock();
+    // prepare the buffer
+    nEntries = p->vForest->nSize - 5;
+    pBuffer = ALLOC( unsigned, nEntries * 2 );
+    for ( i = 0; i < nEntries; i++ )
+    {
+        pNode = p->vForest->pArray[i+5];
+        pBuffer[2*i + 0] = (Rwr_Regular(pNode->p0)->Id << 1) | Rwr_IsComplement(pNode->p0);
+        pBuffer[2*i + 1] = (Rwr_Regular(pNode->p1)->Id << 1) | Rwr_IsComplement(pNode->p1);
+        // save EXOR flag
+        pBuffer[2*i + 0] = (pBuffer[2*i + 0] << 1) | pNode->fExor;
+
+    }
+    pFile = fopen( pFileName, "wb" );
+    fwrite( &nEntries, sizeof(int), 1, pFile );
+    fwrite( pBuffer, sizeof(unsigned), nEntries * 2, pFile );
+    free( pBuffer );
+    fclose( pFile );
+    printf( "The number of nodes saved = %d.   ", nEntries );  PRT( "Saving", clock() - clk );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Loads data from file.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManLoadFromFile( Abc_ManRwr_t * p, char * pFileName )
+{
+    FILE * pFile;
+    Rwr_Node_t * p0, * p1;
+    unsigned * pBuffer;
+    int Level, Volume, nEntries, fExor;
+    int i, clk = clock();
+
+    // load the data
+    pFile = fopen( pFileName, "rb" );
+    if ( pFile == NULL )
+    {
+        printf( "Rwr_ManLoadFromFile: Cannot open file \"%s\".\n", pFileName );
+        return;
+    }
+    fread( &nEntries, sizeof(int), 1, pFile );
+    pBuffer = ALLOC( unsigned, nEntries * 2 );
+    fread( pBuffer, sizeof(unsigned), nEntries * 2, pFile );
+    fclose( pFile );
+    // reconstruct the forest
+    for ( i = 0; i < nEntries; i++ )
+    {
+        // get EXOR flag
+        fExor = (pBuffer[2*i + 0] & 1);
+        pBuffer[2*i + 0] = (pBuffer[2*i + 0] >> 1);
+        // get the nodes
+        p0 = p->vForest->pArray[pBuffer[2*i + 0] >> 1];
+        p1 = p->vForest->pArray[pBuffer[2*i + 1] >> 1];
+        // compute the level and volume of the new nodes
+        Level  = 1 + ABC_MAX( p0->Level, p1->Level );
+        Volume = 1 + Rwr_ManNodeVolume( p, p0, p1 );
+        // set the complemented attributes
+        p0 = Rwr_NotCond( p0, (pBuffer[2*i + 0] & 1) );
+        p1 = Rwr_NotCond( p1, (pBuffer[2*i + 1] & 1) );
+        // add the node
+//        Rwr_ManTryNode( p, p0, p1, Level, Volume );
+        Rwr_ManAddNode( p, p0, p1, fExor, Level, Volume + fExor );
+    }
+    free( pBuffer );
+    printf( "The number of classes = %d. Canonical nodes = %d.\n", p->nClasses, p->nAdded );
+    printf( "The number of nodes loaded = %d.   ", nEntries );  PRT( "Loading", clock() - clk );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManIncTravId_int( Abc_ManRwr_t * p )
+{
+    Rwr_Node_t * pNode;
+    int i;
+    Vec_PtrForEachEntry( p->vForest, pNode, i )
+        pNode->TravId = 0;
+    p->nTravIds = 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_MarkUsed_rec( Abc_ManRwr_t * p, Rwr_Node_t * pNode )
+{
+    if ( pNode->fUsed || pNode->TravId == p->nTravIds )
+        return;
+    pNode->TravId = p->nTravIds;
+    pNode->fUsed = 1;
+    Rwr_MarkUsed_rec( p, Rwr_Regular(pNode->p0) );
+    Rwr_MarkUsed_rec( p, Rwr_Regular(pNode->p1) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_Trav_rec( Abc_ManRwr_t * p, Rwr_Node_t * pNode, int * pVolume )
+{
+    if ( pNode->fMark || pNode->TravId == p->nTravIds )
+        return;
+    pNode->TravId = p->nTravIds;
+    (*pVolume)++;
+    if ( pNode->fExor )
+        (*pVolume)++;
+    Rwr_Trav_rec( p, Rwr_Regular(pNode->p0), pVolume );
+    Rwr_Trav_rec( p, Rwr_Regular(pNode->p1), pVolume );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_Trav2_rec( Abc_ManRwr_t * p, Rwr_Node_t * pNode, int * pVolume )
+{
+    if ( pNode->fMark || pNode->TravId == p->nTravIds )
+        return;
+    pNode->TravId = p->nTravIds;
+    (*pVolume)++;
+    Rwr_Trav2_rec( p, Rwr_Regular(pNode->p0), pVolume );
+    Rwr_Trav2_rec( p, Rwr_Regular(pNode->p1), pVolume );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_ManNodeVolume( Abc_ManRwr_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1 )
+{
+    int Volume = 0;
+    Rwr_ManIncTravId( p );
+    Rwr_Trav_rec( p, p0, &Volume );
+    Rwr_Trav_rec( p, p1, &Volume );
+    return Volume;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Node_t * Rwr_ManTryNode( Abc_ManRwr_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1, int fExor, int Level, int Volume )
+{
+    Rwr_Node_t * pOld, * pNew, ** ppPlace;
+    unsigned uTruth, uCanon;
+    // compute truth table, level, volume
+    p->nConsidered++;
+    if ( fExor )
+    {
+//        printf( "Considering EXOR of %d and %d.\n", p0->Id, p1->Id );
+        uTruth = (p0->uTruth ^ p1->uTruth);
+    }
+    else
+        uTruth = (Rwr_IsComplement(p0)? ~Rwr_Regular(p0)->uTruth : Rwr_Regular(p0)->uTruth) & 
+                 (Rwr_IsComplement(p1)? ~Rwr_Regular(p1)->uTruth : Rwr_Regular(p1)->uTruth) & 0xFFFF;
+    uCanon = p->puCanons[uTruth];
+    // skip non-practical classes
+    if ( Level > 2 && p->pPractical[uCanon] == 0 )
+        return NULL;
+    // enumerate through the nodes with the same canonical form
+    ppPlace = p->pTable + uCanon;
+    for ( pOld = *ppPlace; pOld; ppPlace = &pOld->pNext, pOld = pOld->pNext )
+    {
+        if ( pOld->Level <  (unsigned)Level && pOld->Volume < (unsigned)Volume )
+            return NULL;
+        if ( pOld->Level == (unsigned)Level && pOld->Volume < (unsigned)Volume )
+            return NULL;
+//        if ( pOld->Level <  (unsigned)Level && pOld->Volume == (unsigned)Volume )
+//            return NULL;
+    }
+//    if ( fExor )
+//        printf( "Adding EXOR of %d and %d.\n", p0->Id, p1->Id );
+    // create the new node
+    pNew = (Rwr_Node_t *)Extra_MmFixedEntryFetch( p->pMmNode );
+    pNew->Id     = p->vForest->nSize;
+    pNew->TravId = 0;
+    pNew->uTruth = uTruth;
+    pNew->Level  = Level;
+    pNew->Volume = Volume;
+    pNew->fMark  = 0;
+    pNew->fUsed  = 0;
+    pNew->fExor  = fExor;
+    pNew->p0     = p0;
+    pNew->p1     = p1;
+    pNew->pNext  = NULL;
+    Vec_PtrPush( p->vForest, pNew );
+    *ppPlace     = pNew;
+    if ( p->pTable[uCanon] == pNew )
+        p->nClasses++;
+    return pNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Node_t * Rwr_ManAddNode( Abc_ManRwr_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1, int fExor, int Level, int Volume )
+{
+    Rwr_Node_t * pOld, * pNew;
+    unsigned uTruth, uCanon;
+    // compute truth table, leve, volume
+    p->nConsidered++;
+    if ( fExor )
+        uTruth = (p0->uTruth ^ p1->uTruth);
+    else
+        uTruth = (Rwr_IsComplement(p0)? ~Rwr_Regular(p0)->uTruth : Rwr_Regular(p0)->uTruth) & 
+                 (Rwr_IsComplement(p1)? ~Rwr_Regular(p1)->uTruth : Rwr_Regular(p1)->uTruth) & 0xFFFF;
+    uCanon = p->puCanons[uTruth];
+    // skip non-practical classes
+//    if ( p->pPractical[uCanon] == 0 )
+//        return NULL;
+    // create the new node
+    pNew = (Rwr_Node_t *)Extra_MmFixedEntryFetch( p->pMmNode );
+    pNew->Id     = p->vForest->nSize;
+    pNew->TravId = 0;
+    pNew->uTruth = uTruth;
+    pNew->Level  = Level;
+    pNew->Volume = Volume;
+    pNew->fMark  = 0;
+    pNew->fUsed  = 0;
+    pNew->fExor  = fExor;
+    pNew->p0     = p0;
+    pNew->p1     = p1;
+    pNew->pNext  = NULL;
+    Vec_PtrPush( p->vForest, pNew );
+    // do not add if the node is not essential
+    if ( uTruth != uCanon )
+        return pNew;
+
+    // add to the list
+    p->nAdded++;
+    pOld = p->pTable[uCanon];
+    if ( pOld == NULL )
+        p->nClasses++;
+    pNew->pNext = pOld;
+    p->pTable[uCanon] = pNew;
+    return pNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Node_t * Rwr_ManAddVar( Abc_ManRwr_t * p, unsigned uTruth )
+{
+    Rwr_Node_t * pNew;
+    pNew = (Rwr_Node_t *)Extra_MmFixedEntryFetch( p->pMmNode );
+    pNew->Id     = p->vForest->nSize;
+    pNew->TravId = 0;
+    pNew->uTruth = uTruth;
+    pNew->Level  = 0;
+    pNew->Volume = 0;
+    pNew->fMark  = 1;
+    pNew->fUsed  = 1;
+    pNew->fExor  = 0;
+    pNew->p0     = NULL;
+    pNew->p1     = NULL;    pNew->pNext  = NULL;
+    Vec_PtrPush( p->vForest, pNew );
+    assert( p->pTable[p->puCanons[uTruth]] == NULL );
+    p->pTable[p->puCanons[uTruth]] = pNew;
+    return pNew;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Prints one rwr node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_NodePrint_rec( FILE * pFile, Rwr_Node_t * pNode )
+{
+    assert( !Rwr_IsComplement(pNode) );
+
+    if ( pNode->Id == 0 )
+    {
+        fprintf( pFile, "Const1" );
+        return;
+    }
+
+    if ( pNode->Id < 5 )
+    {
+        fprintf( pFile, "%c", 'a' + pNode->Id - 1 );
+        return;
+    }
+
+    if ( Rwr_IsComplement(pNode->p0) )
+    {
+        if ( Rwr_Regular(pNode->p0)->Id < 5 )
+        {
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p0) );
+            fprintf( pFile, "\'" );
+        }
+        else
+        {
+            fprintf( pFile, "(" );
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p0) );
+            fprintf( pFile, ")\'" );
+        }
+    }
+    else
+    {
+        if ( Rwr_Regular(pNode->p0)->Id < 5 )
+        {
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p0) );
+        }
+        else
+        {
+            fprintf( pFile, "(" );
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p0) );
+            fprintf( pFile, ")" );
+        }
+    }
+
+    if ( pNode->fExor )
+        fprintf( pFile, "+" );
+
+    if ( Rwr_IsComplement(pNode->p1) )
+    {
+        if ( Rwr_Regular(pNode->p1)->Id < 5 )
+        {
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p1) );
+            fprintf( pFile, "\'" );
+        }
+        else
+        {
+            fprintf( pFile, "(" );
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p1) );
+            fprintf( pFile, ")\'" );
+        }
+    }
+    else
+    {
+        if ( Rwr_Regular(pNode->p1)->Id < 5 )
+        {
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p1) );
+        }
+        else
+        {
+            fprintf( pFile, "(" );
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p1) );
+            fprintf( pFile, ")" );
+        }
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints one rwr node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_NodePrint( FILE * pFile, Abc_ManRwr_t * p, Rwr_Node_t * pNode )
+{
+    unsigned uTruth;
+    fprintf( pFile, "%5d :", pNode->Id );
+    fprintf( pFile, " tt=", pNode->Id );
+    uTruth = pNode->uTruth;
+    Extra_PrintBinary( pFile, &uTruth, 16 );
+    fprintf( pFile, " cn=", pNode->Id );
+    uTruth = p->puCanons[pNode->uTruth];
+    Extra_PrintBinary( pFile, &uTruth, 16 );
+    fprintf( pFile, " lev=%d", pNode->Level );
+    fprintf( pFile, " vol=%d", pNode->Volume );
+    fprintf( pFile, "  " );
+    Rwr_NodePrint_rec( pFile, pNode );
+    fprintf( pFile, "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints one rwr node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManPrint( Abc_ManRwr_t * p )
+{
+/*
+    Rwr_Node_t * pNode;
+    unsigned uTruth;
+    int Limit = 4;
+    int i;
+
+    for ( i = 0; i < p->nFuncs; i++ )
+    {
+        if ( p->pTable[i] == NULL )
+            continue;
+        if ( Limit-- == 0 )
+            break;
+        printf( "\nClass " );
+        uTruth = i;
+        Extra_PrintBinary( stdout, &uTruth, 16 );
+        printf( "\n" );
+        for ( pNode = p->pTable[i]; pNode; pNode = pNode->pNext )
+            if ( pNode->uTruth == p->puCanons[pNode->uTruth] )
+                Rwr_NodePrint( p, pNode );
+    }
+*/
+    FILE * pFile;
+    Rwr_Node_t * pNode;
+    unsigned uTruth;
+    int Limit = 4;
+    int Counter;
+    int i;
+
+    pFile = fopen( "graph_lib.txt", "w" );
+
+    Counter = 0;
+    for ( i = 0; i < p->nFuncs; i++ )
+    {
+        if ( p->pTable[i] == NULL )
+            continue;
+//        if ( Limit-- == 0 )
+//            break;
+        fprintf( pFile, "\nClass %3d  ", Counter++ );
+
+        // count the volume of the bush
+        {
+            int Volume = 0;
+            int nFuncs = 0;
+            Rwr_ManIncTravId( p );
+            for ( pNode = p->pTable[i]; pNode; pNode = pNode->pNext )
+                if ( pNode->uTruth == p->puCanons[pNode->uTruth] )
+                {
+                    nFuncs++;
+                    Rwr_Trav2_rec( p, pNode, &Volume );
+                }
+            fprintf( pFile, "Functions = %2d. Volume = %2d. ", nFuncs, Volume );
+        }
+
+        uTruth = i;
+        Extra_PrintBinary( pFile, &uTruth, 16 );
+        fprintf( pFile, "\n" );
+
+        for ( pNode = p->pTable[i]; pNode; pNode = pNode->pNext )
+            if ( pNode->uTruth == p->puCanons[pNode->uTruth] )
+                Rwr_NodePrint( pFile, p, pNode );
+    }
+
+    fclose( pFile );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrMan.c b/src/opt/rwr/rwrMan.c
new file mode 100644
index 00000000..46752696
--- /dev/null
+++ b/src/opt/rwr/rwrMan.c
@@ -0,0 +1,311 @@
+/**CFile****************************************************************
+
+  FileName    [rwrMan.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrMan.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// the following information was derived by computing all 4-input cuts of IWLS, MCNC, and ISCAS benchmarks
+#define RWR_NUM_CLASSES  775
+static int s_PracticalClasses[RWR_NUM_CLASSES] = {
+    0, 1, 3, 5, 6, 7, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 51, 53, 54, 55, 60, 61, 63, 85, 86, 
+    87, 90, 91, 95, 102, 103, 105, 107, 111, 119, 123, 125, 126, 127, 255, 257, 258, 259, 260, 261, 262, 263, 264, 265, 
+    266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 277, 278, 281, 282, 284, 286, 287, 288, 289, 290, 291, 293, 297, 
+    298, 299, 300, 302, 303, 304, 305, 306, 307, 308, 310, 311, 312, 313, 315, 316, 317, 319, 320, 321, 323, 324, 325, 329, 
+    332, 334, 335, 336, 337, 338, 340, 341, 342, 343, 345, 347, 349, 351, 352, 357, 358, 359, 361, 367, 368, 369, 371, 
+    373, 375, 379, 381, 383, 384, 385, 386, 388, 389, 392, 393, 395, 397, 399, 400, 404, 408, 409, 416, 417, 419, 420, 
+    421, 424, 425, 426, 427, 431, 433, 443, 448, 449, 451, 453, 456, 457, 459, 460, 461, 462, 463, 465, 476, 477, 480, 
+    481, 483, 489, 492, 493, 494, 495, 496, 497, 499, 500, 501, 506, 507, 508, 509, 510, 771, 773, 774, 775, 780, 781, 
+    783, 785, 786, 787, 788, 790, 791, 792, 796, 797, 799, 816, 817, 819, 820, 821, 834, 835, 836, 837, 838, 839, 840, 
+    844, 847, 848, 849, 850, 851, 852, 853, 854, 855, 856, 859, 860, 861, 863, 864, 867, 870, 871, 876, 878, 880, 883, 
+    884, 885, 887, 967, 973, 975, 979, 984, 988, 989, 990, 1009, 1011, 1012, 1013, 1020, 1285, 1286, 1287, 1290, 1291, 
+    1295, 1297, 1298, 1300, 1301, 1303, 1307, 1308, 1309, 1311, 1314, 1316, 1317, 1318, 1319, 1322, 1325, 1327, 1329, 
+    1330, 1331, 1332, 1333, 1334, 1335, 1336, 1338, 1340, 1341, 1360, 1361, 1363, 1365, 1367, 1380, 1381, 1382, 1383, 
+    1390, 1392, 1395, 1397, 1399, 1440, 1445, 1447, 1450, 1451, 1455, 1458, 1461, 1463, 1467, 1525, 1530, 1542, 1543, 
+    1545, 1547, 1551, 1553, 1554, 1558, 1559, 1561, 1567, 1569, 1570, 1572, 1574, 1576, 1587, 1588, 1590, 1591, 1596, 
+    1618, 1620, 1621, 1623, 1624, 1632, 1638, 1641, 1647, 1654, 1655, 1680, 1686, 1687, 1689, 1695, 1718, 1776, 1782, 
+    1785, 1799, 1803, 1805, 1806, 1807, 1811, 1813, 1815, 1823, 1826, 1831, 1843, 1844, 1847, 1859, 1860, 1863, 1875, 
+    1877, 1879, 1895, 1902, 1904, 1911, 1912, 1927, 1928, 1933, 1935, 1945, 1956, 1957, 1959, 1962, 1964, 1965, 1975, 
+    1979, 1987, 1991, 1995, 1996, 2000, 2002, 2007, 2013, 2023, 2032, 2040, 3855, 3857, 3859, 3861, 3864, 3866, 3867, 
+    3868, 3869, 3870, 3891, 3892, 3893, 3900, 3921, 3925, 3942, 3945, 3956, 3960, 4080, 4369, 4370, 4371, 4372, 4373, 
+    4374, 4375, 4376, 4377, 4378, 4379, 4380, 4381, 4382, 4386, 4387, 4388, 4389, 4391, 4392, 4394, 4396, 4403, 4405, 
+    4408, 4409, 4411, 4420, 4421, 4422, 4423, 4424, 4426, 4428, 4437, 4439, 4445, 4488, 4494, 4505, 4507, 4509, 4522, 
+    4524, 4525, 4526, 4539, 4540, 4542, 4556, 4557, 4573, 4574, 4590, 4626, 4627, 4629, 4630, 4631, 4632, 4634, 4638, 
+    4641, 4643, 4648, 4659, 4680, 4695, 4698, 4702, 4713, 4731, 4740, 4758, 4766, 4773, 4791, 4812, 4830, 4845, 4883, 
+    4885, 4887, 4888, 4891, 4892, 4899, 4903, 4913, 4914, 4915, 4934, 4940, 4945, 4947, 4949, 4951, 4972, 5005, 5011, 
+    5017, 5019, 5029, 5043, 5049, 5058, 5059, 5060, 5068, 5075, 5079, 5083, 5084, 5100, 5140, 5141, 5142, 5143, 5148, 
+    5160, 5171, 5174, 5180, 5182, 5185, 5186, 5187, 5189, 5205, 5207, 5214, 5238, 5245, 5246, 5250, 5270, 5278, 5290, 
+    5310, 5315, 5335, 5355, 5397, 5399, 5401, 5402, 5405, 5413, 5414, 5415, 5418, 5427, 5429, 5445, 5457, 5460, 5461, 
+    5463, 5469, 5482, 5522, 5525, 5533, 5540, 5546, 5557, 5565, 5571, 5580, 5589, 5593, 5605, 5610, 5654, 5673, 5692, 
+    5698, 5729, 5734, 5782, 5790, 5796, 5814, 5826, 5846, 5911, 5931, 5965, 6001, 6066, 6120, 6168, 6174, 6180, 6206, 
+    6210, 6229, 6234, 6270, 6273, 6279, 6363, 6375, 6425, 6427, 6438, 6446, 6451, 6457, 6478, 6482, 6485, 6489, 6502, 
+    6545, 6553, 6564, 6570, 6594, 6617, 6630, 6682, 6683, 6685, 6686, 6693, 6709, 6741, 6746, 6817, 6821, 6826, 6833, 
+    6849, 6885, 6939, 6940, 6951, 6963, 6969, 6990, 6997, 7065, 7077, 7089, 7140, 7196, 7212, 7219, 7220, 7228, 7230, 
+    7251, 7324, 7356, 7361, 7363, 7372, 7377, 7395, 7453, 7470, 7475, 7495, 7509, 7513, 7526, 7619, 7633, 7650, 7710, 
+    7725, 7731, 7740, 7755, 7770, 7800, 7815, 7830, 7845, 7860, 7890, 7905, 13107, 13109, 13110, 13116, 13141, 13146, 
+    13161, 13164, 13621, 13622, 13626, 13651, 13653, 13658, 13669, 13670, 13763, 13765, 13770, 13878, 13881, 13884, 
+    13910, 13923, 13926, 13932, 13971, 13974, 13980, 14022, 14025, 15420, 15445, 15450, 15462, 15465, 15555, 21845, 
+    21846, 21850, 21865, 21866, 21930, 22102, 22105, 22106, 22117, 22118, 22122, 22165, 22166, 22169, 22170, 22181, 
+    22182, 22185, 23130, 23142, 23145, 23205, 26214, 26217, 26985, 27030 
+};
+
+static unsigned short      Rwr_FunctionPerm( unsigned uTruth, int Phase );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_ManRwr_t * Abc_NtkManRwrStart( char * pFileName )
+{
+    Abc_ManRwr_t * p;
+    unsigned uTruth;
+    int i, k, nClasses;
+    int clk = clock();
+
+    p = ALLOC( Abc_ManRwr_t, 1 );
+    memset( p, 0, sizeof(Abc_ManRwr_t) );
+    // canonical forms
+    p->nFuncs    = (1<<16);
+    p->puCanons  = ALLOC( unsigned short, p->nFuncs );
+    memset( p->puCanons, 0, sizeof(unsigned short) * p->nFuncs );
+    // permutations
+    p->puPhases  = ALLOC( char, p->nFuncs );
+    memset( p->puPhases, 0, sizeof(char) * p->nFuncs );
+    // hash table
+    p->pTable  = ALLOC( Rwr_Node_t *, p->nFuncs );
+    memset( p->pTable, 0, sizeof(Rwr_Node_t *) * p->nFuncs );
+    // practical classes
+    p->pPractical  = ALLOC( char, p->nFuncs );
+    memset( p->pPractical, 0, sizeof(char) * p->nFuncs );
+    // other stuff
+    p->vForest  = Vec_PtrAlloc( 100 );
+    p->vForm    = Vec_IntAlloc( 50 );
+    p->vFanins  = Vec_PtrAlloc( 50 );
+    p->vTfo     = Vec_PtrAlloc( 50 );
+    p->vLevels  = Vec_VecAlloc( 50 );
+    p->pMmNode  = Extra_MmFixedStart( sizeof(Rwr_Node_t) );
+    p->nTravIds = 1;
+    assert( sizeof(Rwr_Node_t) == sizeof(Rwr_Cut_t) );
+
+    // initialize the canonical forms
+    nClasses = 1;
+    for ( i = 1; i < p->nFuncs-1; i++ )
+    {
+        if ( p->puCanons[i] )
+            continue;
+        nClasses++;
+        for ( k = 0; k < 32; k++ )
+        {
+            uTruth = Rwr_FunctionPhase( (unsigned)i, (unsigned)k );
+            if ( p->puCanons[uTruth] == 0 )
+            {
+                p->puCanons[uTruth] = (unsigned short)i;
+                p->puPhases[uTruth] = (char)k;
+            }
+            else
+                assert( p->puCanons[uTruth] == (unsigned short)i );
+        }
+    }
+    // set info for constant 1
+    p->puCanons[p->nFuncs-1] = 0;
+    p->puPhases[p->nFuncs-1] = 16;
+    printf( "The number of NN-canonical forms = %d.\n", nClasses );
+
+    // initialize permutations
+    for ( i = 0; i < 256; i++ )
+        for ( k = 0; k < 16; k++ )
+            p->puPerms[i][k] = Rwr_FunctionPerm( i, k );
+
+    // initialize practical classes
+    for ( i = 0; i < RWR_NUM_CLASSES; i++ )
+        p->pPractical[ s_PracticalClasses[i] ] = 1;
+
+    // initialize forest
+    Rwr_ManAddVar( p, 0xFFFF ); // constant 1
+    Rwr_ManAddVar( p, 0xAAAA ); // var A
+    Rwr_ManAddVar( p, 0xCCCC ); // var B
+    Rwr_ManAddVar( p, 0xF0F0 ); // var C
+    Rwr_ManAddVar( p, 0xFF00 ); // var D
+    p->nClasses = 5;
+PRT( "Manager startup time", clock() - clk ); 
+
+    // create the nodes
+    if ( pFileName == NULL )
+    {   // precompute
+        Rwr_ManPrecompute( p );
+        Rwr_ManWriteToFile( p, "data.aaa" );
+    }
+    else
+    {   // load previously saved nodes
+        Rwr_ManLoadFromFile( p, pFileName );
+    }
+    Rwr_ManPrint( p );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkManRwrStop( Abc_ManRwr_t * p )
+{
+    if ( p->vFanNums )  Vec_IntFree( p->vFanNums );
+    if ( p->vReqTimes ) Vec_IntFree( p->vReqTimes );
+    Vec_IntFree( p->vForm );
+    Vec_PtrFree( p->vFanins );
+    Vec_PtrFree( p->vTfo );
+    Vec_VecFree( p->vLevels );
+    Vec_PtrFree( p->vForest );
+    Extra_MmFixedStop( p->pMmNode,   0 );
+    free( p->pPractical );
+    free( p->puCanons );
+    free( p->puPhases );
+    free( p->pTable );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Abc_NtkManRwrDecs( Abc_ManRwr_t * p )
+{
+    return p->vForm;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Abc_NtkManRwrFanins( Abc_ManRwr_t * p )
+{
+    return p->vFanins;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes a phase of the 4-var function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned short Rwr_FunctionPhase( unsigned uTruth, unsigned uPhase )
+{
+    static unsigned uMasks0[4] = { 0x5555, 0x3333, 0x0F0F, 0x00FF };
+    static unsigned uMasks1[4] = { 0xAAAA, 0xCCCC, 0xF0F0, 0xFF00 };
+    int v, Shift;
+    for ( v = 0, Shift = 1; v < 4; v++, Shift <<= 1 )
+        if ( uPhase & Shift )
+            uTruth = (((uTruth & uMasks0[v]) << Shift) | ((uTruth & uMasks1[v]) >> Shift));
+    if ( uPhase & 16 )
+        uTruth = ~uTruth & 0xFFFF;
+    return uTruth;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes a phase of the 3-var function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned short Rwr_FunctionPerm( unsigned uTruth, int Phase )
+{
+    static int Perm[16][4] = {
+        { 0, 1, 2, 3 }, // 0000  - skip
+        { 0, 1, 2, 3 }, // 0001  - skip
+        { 1, 0, 2, 3 }, // 0010
+        { 0, 1, 2, 3 }, // 0011  - skip
+        { 2, 1, 0, 3 }, // 0100
+        { 0, 2, 1, 3 }, // 0101
+        { 2, 0, 1, 3 }, // 0110
+        { 0, 1, 2, 3 }, // 0111  - skip
+        { 3, 1, 2, 0 }, // 1000
+        { 0, 3, 2, 1 }, // 1001
+        { 3, 0, 2, 1 }, // 1010
+        { 0, 1, 3, 2 }, // 1011
+        { 2, 3, 0, 1 }, // 1100
+        { 0, 3, 1, 2 }, // 1101
+        { 3, 0, 1, 2 }, // 1110
+        { 0, 1, 2, 3 }  // 1111  - skip
+    };
+    int i, k, iRes;
+    unsigned uTruthRes;
+    assert( Phase < 16 );
+    uTruthRes = 0;
+    for ( i = 0; i < 16; i++ )
+        if ( uTruth & (1 << i) )
+        {
+            for ( iRes = 0, k = 0; k < 4; k++ )
+                if ( i & (1 << k) )
+                    iRes |= (1 << Perm[Phase][k]);
+            uTruthRes |= (1 << iRes);
+        }
+    return uTruthRes;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrUtil.c b/src/opt/rwr/rwrUtil.c
new file mode 100644
index 00000000..ae8665ef
--- /dev/null
+++ b/src/opt/rwr/rwrUtil.c
@@ -0,0 +1,102 @@
+/**CFile****************************************************************
+
+  FileName    [rwrUtil.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Various utilities.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrUtil.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the array of fanout counters.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Rwt_NtkFanoutCounters( Abc_Ntk_t * pNtk )
+{
+    Vec_Int_t * vFanNums;
+    Abc_Obj_t * pObj;
+    int i;
+    vFanNums = Vec_IntAlloc( 0 );
+    Vec_IntFill( vFanNums, Abc_NtkObjNumMax(pNtk), -1 );
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjIsNode( pObj ) )
+            Vec_IntWriteEntry( vFanNums, i, Abc_ObjFanoutNum(pObj) );
+    return vFanNums;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the array of required times.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Rwt_NtkRequiredLevels( Abc_Ntk_t * pNtk )
+{
+    Vec_Int_t * vReqTimes;
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pObj, * pFanout;
+    int i, k, nLevelsMax, nLevelsCur;
+    // start the required times
+    vReqTimes = Vec_IntAlloc( 0 );
+    Vec_IntFill( vReqTimes, Abc_NtkObjNumMax(pNtk), ABC_INFINITY );
+    // compute levels in reverse topological order
+    Abc_NtkForEachCo( pNtk, pObj, i )
+        Vec_IntWriteEntry( vReqTimes, pObj->Id, 0 );
+    vNodes = Abc_NtkDfsReverse( pNtk );
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+    {
+        nLevelsCur = 0;
+        Abc_ObjForEachFanout( pObj, pFanout, k )
+            if ( nLevelsCur < Vec_IntEntry(vReqTimes, pFanout->Id) )
+                nLevelsCur = Vec_IntEntry(vReqTimes, pFanout->Id);
+        Vec_IntWriteEntry( vReqTimes, pObj->Id, nLevelsCur + 1 );
+    }
+    Vec_PtrFree( vNodes );
+    // convert levels into required times: RetTime = NumLevels + 1 - Level
+    nLevelsMax = Abc_AigGetLevelNum(pNtk) + 1;
+    Abc_NtkForEachNode( pNtk, pObj, i )
+        Vec_IntWriteEntry( vReqTimes, pObj->Id, nLevelsMax - Vec_IntEntry(vReqTimes, pObj->Id) );
+//    Abc_NtkForEachNode( pNtk, pObj, i )
+//        printf( "(%d,%d)", pObj->Level, Vec_IntEntry(vReqTimes, pObj->Id) );
+//    printf( "\n" );
+    return vReqTimes;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+