Changes to the matching procedure and new abstraction code.

1 files changed, 708 insertions, 0 deletions

diff --git a/src/map/if/ifDec16.c b/src/map/if/ifDec16.c
new file mode 100644
index 00000000..5e988ae5
--- /dev/null
+++ b/src/map/if/ifDec16.c
@@ -0,0 +1,708 @@
+/**CFile****************************************************************
+
+  FileName    [ifDec10f.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [FPGA mapping based on priority cuts.]
+
+  Synopsis    [Fast checking procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - November 21, 2006.]
+
+  Revision    [$Id: ifDec10f.c,v 1.00 2006/11/21 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "if.h"
+
+ABC_NAMESPACE_IMPL_START
+
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define CLU_VAR_MAX  16
+#define CLU_WRD_MAX  (1 << ((CLU_VAR_MAX)-6))
+
+// decomposition
+typedef struct If_Grp_t_ If_Grp_t;
+struct If_Grp_t_
+{
+    char nVars;
+    char nMyu;
+    char pVars[6];
+};
+
+// the bit count for the first 256 integer numbers
+static int BitCount8[256] = {
+    0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,
+    1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
+    1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
+    2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
+    1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
+    2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
+    2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
+    3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,4,5,5,6,5,6,6,7,5,6,6,7,6,7,7,8
+};
+// variable swapping code
+static word PMasks[5][3] = {
+    { 0x9999999999999999, 0x2222222222222222, 0x4444444444444444 },
+    { 0xC3C3C3C3C3C3C3C3, 0x0C0C0C0C0C0C0C0C, 0x3030303030303030 },
+    { 0xF00FF00FF00FF00F, 0x00F000F000F000F0, 0x0F000F000F000F00 },
+    { 0xFF0000FFFF0000FF, 0x0000FF000000FF00, 0x00FF000000FF0000 },
+    { 0xFFFF00000000FFFF, 0x00000000FFFF0000, 0x0000FFFF00000000 }
+};
+// elementary truth tables
+static word Truth6[6] = {
+    0xAAAAAAAAAAAAAAAA,
+    0xCCCCCCCCCCCCCCCC,
+    0xF0F0F0F0F0F0F0F0,
+    0xFF00FF00FF00FF00,
+    0xFFFF0000FFFF0000,
+    0xFFFFFFFF00000000
+};
+static word TruthAll[CLU_VAR_MAX][CLU_WRD_MAX];
+
+extern void Kit_DsdPrintFromTruth( unsigned * pTruth, int nVars );
+extern void Extra_PrintBinary( FILE * pFile, unsigned Sign[], int nBits );
+
+//  group representation (MSB <-> LSB)
+//  nVars | nMyu | v5 | v4 | v3 | v2 | v1 | v0 
+//  if nCofs > 2, v0 is the shared variable
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+void If_CluInitTruthTables()
+{
+    int i, k;
+    assert( CLU_VAR_MAX <= 16 );
+    for ( i = 0; i < 6; i++ )
+        for ( k = 0; k < CLU_WRD_MAX; k++ )
+            TruthAll[i][k] = Truth6[i];
+    for ( i = 6; i < CLU_VAR_MAX; i++ )
+        for ( k = 0; k < CLU_WRD_MAX; k++ )
+            TruthAll[i][k] = ((k >> i) & 1) ? ~0 : 0;
+}
+
+// variable permutation for large functions
+static inline int If_CluWordNum( int nVars )
+{
+    return nVars <= 6 ? 1 : 1 << (nVars-6);
+}
+static inline void If_CluCopy( word * pOut, word * pIn, int nVars )
+{
+    int w, nWords = If_CluWordNum( nVars );
+    for ( w = 0; w < nWords; w++ )
+        pOut[w] = pIn[w];
+}
+static inline int If_CluEqual( word * pOut, word * pIn, int nVars )
+{
+    int w, nWords = If_CluWordNum( nVars );
+    for ( w = 0; w < nWords; w++ )
+        if ( pOut[w] != pIn[w] )
+            return 0;
+    return 1;
+}
+static inline void If_CluSwapAdjacent( word * pOut, word * pIn, int iVar, int nVars )
+{
+    int i, k, nWords = If_CluWordNum( nVars );
+    assert( iVar < nVars - 1 );
+    if ( iVar < 5 )
+    {
+        int Shift = (1 << iVar);
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = (pIn[i] & PMasks[iVar][0]) | ((pIn[i] & PMasks[iVar][1]) << Shift) | ((pIn[i] & PMasks[iVar][2]) >> Shift);
+    }
+    else if ( iVar > 5 )
+    {
+        int Step = (1 << (iVar - 6));
+        for ( k = 0; k < nWords; k += 4*Step )
+        {
+            for ( i = 0; i < Step; i++ )
+                pOut[i] = pIn[i];
+            for ( i = 0; i < Step; i++ )
+                pOut[Step+i] = pIn[2*Step+i];
+            for ( i = 0; i < Step; i++ )
+                pOut[2*Step+i] = pIn[Step+i];
+            for ( i = 0; i < Step; i++ )
+                pOut[3*Step+i] = pIn[3*Step+i];
+            pIn  += 4*Step;
+            pOut += 4*Step;
+        }
+    }
+    else // if ( iVar == 5 )
+    {
+        for ( i = 0; i < nWords; i += 2 )
+        {
+            pOut[i]   = (pIn[i]   & 0x00000000FFFFFFFF) | ((pIn[i+1] & 0x00000000FFFFFFFF) << 32);
+            pOut[i+1] = (pIn[i+1] & 0xFFFFFFFF00000000) | ((pIn[i]   & 0xFFFFFFFF00000000) >> 32);
+        }
+    }
+}
+
+// moves one var (v) to the given position (p)
+void If_CluMoveVar( word * pF, int nVars, int * Var2Pla, int * Pla2Var, int v, int p )
+{
+    word pG[CLU_WRD_MAX], * pIn = pF, * pOut = pG, * pTemp;
+    int iPlace0, iPlace1, Count = 0;
+    assert( v >= 0 && v < nVars );
+    if ( Var2Pla[v] <= p )
+    {
+        while ( Var2Pla[v] < p )
+        {
+            iPlace0 = Var2Pla[v];
+            iPlace1 = Var2Pla[v]+1;
+            If_CluSwapAdjacent( pOut, pIn, iPlace0, nVars );
+            pTemp = pIn; pIn = pOut, pOut = pTemp;
+            Var2Pla[Pla2Var[iPlace0]]++;
+            Var2Pla[Pla2Var[iPlace1]]--;
+            Pla2Var[iPlace0] ^= Pla2Var[iPlace1];
+            Pla2Var[iPlace1] ^= Pla2Var[iPlace0];
+            Pla2Var[iPlace0] ^= Pla2Var[iPlace1];
+            Count++;
+        }
+    }
+    else
+    {
+        while ( Var2Pla[v] > p )
+        {
+            iPlace0 = Var2Pla[v]-1;
+            iPlace1 = Var2Pla[v];
+            If_CluSwapAdjacent( pOut, pIn, iPlace0, nVars );
+            pTemp = pIn; pIn = pOut, pOut = pTemp;
+            Var2Pla[Pla2Var[iPlace0]]++;
+            Var2Pla[Pla2Var[iPlace1]]--;
+            Pla2Var[iPlace0] ^= Pla2Var[iPlace1];
+            Pla2Var[iPlace1] ^= Pla2Var[iPlace0];
+            Pla2Var[iPlace0] ^= Pla2Var[iPlace1];
+            Count++;
+        }
+    }
+    if ( Count & 1 )
+        If_CluCopy( pF, pIn, nVars );
+    assert( Pla2Var[p] == v );
+}
+
+// moves vars to be the most signiticant ones (Group[0] is MSB)
+void If_CluMoveGroupToMsb( word * pF, int nVars, int * V2P, int * P2V, If_Grp_t * g )
+{
+    int v;
+    for ( v = 0; v < g->nVars; v++ )
+        If_CluMoveVar( pF, nVars, V2P, P2V, g->pVars[g->nVars - 1 - v], nVars - 1 - v );
+}
+
+// return the number of cofactors w.r.t. the topmost vars (nBSsize)
+int If_CluCountCofs( word * pF, int nVars, int nBSsize, int iShift, word * pCofs[2] )
+{
+    word iCofs[64], iCof;
+    int i, c, w, nMints = (1 << nBSsize), nCofs;
+
+    assert( nBSsize < nVars );
+    assert( nBSsize >= 3 && nBSsize <= 6 );
+
+    if ( nVars - nBSsize >= 6 )
+    {
+        word * pCofA, * pCofB;
+        int nWords = (1 << (nVars - nBSsize - 6));
+        assert( nWords * nMints == If_CluWordNum(nVars) );
+        for ( nCofs = i = 0; i < nMints; i++ )
+        {
+            for ( c = 0; c < nCofs; c++ )
+            {
+                pCofA = pF + i * nWords;
+                pCofB = pF + iCofs[c] * nWords;
+                for ( w = 0; w < nWords; w++ )
+                    if ( pCofA[w] != pCofB[w] )
+                        break;
+                if ( w == nWords )
+                    break;
+            }
+            if ( c == nCofs )
+                iCofs[nCofs++] = i;
+            if ( nCofs == 5 )
+                break;
+        }
+        if ( nCofs == 2 && pCofs )
+        {
+            for ( c = 0; c < nCofs; c++ )
+            {
+                word * pCofA = pF + iCofs[c] * nWords;
+                for ( w = 0; w < nWords; w++ )
+                    pCofs[c][w] = pCofA[w];
+            }
+        }
+    }
+    else
+    {
+        int nShift = (1 << (nVars - nBSsize));
+        word Mask  = ((((word)1) << nShift) - 1);
+        for ( nCofs = i = 0; i < nMints; i++ )
+        {
+            iCof = (pF[(iShift + i * nShift) / 64] >> ((iShift + i * nShift) & 63)) & Mask;
+            for ( c = 0; c < nCofs; c++ )
+                if ( iCof == iCofs[c] )
+                    break;
+            if ( c == nCofs )
+                iCofs[nCofs++] = iCof;
+            if ( nCofs == 5 )
+                break;
+        }
+    }
+    assert( nCofs >= 2 && nCofs <= 5 );
+    return nCofs;
+}
+
+void If_CluCofactors( word * pF, int nVars, int iVar, word * pCof0, word * pCof1 )
+{
+    int nWords = If_CluWordNum( nVars );
+    assert( iVar < nVars );
+    if ( iVar < 6 )
+    {
+        int i, Shift = (1 << iVar);
+        for ( i = 0; i < nWords; i++ )
+        {
+            pCof0[i] = (pF[i] & ~Truth6[iVar]) | ((pF[i] & ~Truth6[iVar]) << Shift);
+            pCof1[i] = (pF[i] &  Truth6[iVar]) | ((pF[i] &  Truth6[iVar]) >> Shift);
+        }
+        return;
+    }
+    else
+    {
+        int i, k, Step = (1 << (iVar - 6));
+        for ( k = 0; k < nWords; k += 2*Step )
+        {
+            for ( i = 0; i < Step; i++ )
+            {
+                pCof0[i] = pCof0[Step+i] = pF[i];
+                pCof1[i] = pCof1[Step+i] = pF[Step+i];
+            }
+            pF    += 2*Step;
+            pCof0 += 2*Step;
+            pCof1 += 2*Step;
+        }
+        return;
+    }
+}
+
+// derives non-disjoint decomposition (assumes the shared var in pG->pVars[pG->nVars-1]
+word If_CluDeriveNonDisjoint( word * pF, int nVars, int * V2P, int * P2V, If_Grp_t * g, If_Grp_t * pG )
+{
+    /*
+    word Truth, Truth0, Truth1;
+    word Cof[2][CLU_WRD_MAX], Cof0[2][CLU_WRD_MAX], Cof1[2][CLU_WRD_MAX];
+    int i, nFSvars, nFSHalfBits, nBSHalfBits;
+    assert( pG->nVars >= 3 && pG->nVar <= 6 );
+    assert( pG->nMyu == 3 || pG->nMyu == 4 );
+
+    If_CluMoveGroupToMsb( pF, nVars, V2P, P2V, pG );
+
+    If_CluCofactors( pF, nVars, nVars - 1, Cof[0], Cof[1] );
+
+    assert( 2 >= If_Dec6CofCount2(c0) );
+    assert( 2 >= If_Dec6CofCount2(c1) );
+
+    assert( 2 >= If_CluCountCofs( Cof[0], nVars - 1, pG->nVars - 1, 0 ) );
+    assert( 2 >= If_CluCountCofs( Cof[1], nVars - 1, pG->nVars - 1, 0 ) );
+
+    Truth0 = If_CluExtract2Cofs( Cof[0], nVars - 1, pG->nVars - 1, &Cof0[0], &Cof0[1] );
+    Truth1 = If_CluExtract2Cofs( Cof[1], nVars - 1, pG->nVars - 1, &Cof0[0], &Cof0[1] );
+
+    nFSHalfBits = (1 << (nVars - pG->nVars - 1));
+    nBSHalfBits = (1 << (pG->nVars - 1))
+
+    Truth = ((Truth0 && ((1 << nBSHalfBits) - 1)) << nBSHalfBits) | (Truth0 && ((1 << nBSHalfBits) - 1))
+
+
+    for ( i = 0; i < 4; i++ )
+        z |= (((word)Pla2Var[i+2]) << (16 + 4*i));
+    z |= ((word)((Cof0[1] << 4) | Cof0[0]) << 32);
+    z |= ((word)((Cof1[1] << 4) | Cof1[0]) << 40);
+    for ( i = 0; i < 2; i++ )
+        z |= (((word)Pla2Var[i]) << (48 + 4*i));
+    z |= (((word)7) << (48 + 4*i++));
+    z |= (((word)Pla2Var[5]) << (48 + 4*i++));
+    assert( i == 4 );
+    return z;
+    */
+    return 0;
+}
+
+
+// check non-disjoint decomposition
+int If_CluCheckNonDisjoint( word * pF, int nVars, int * V2P, int * P2V, If_Grp_t * g )
+{
+    int v, i, nCofsBest2;
+    if ( (g->nMyu == 3 || g->nMyu == 4) )
+    {
+        word pCof0[CLU_WRD_MAX];
+        word pCof1[CLU_WRD_MAX];
+        // try cofactoring w.r.t. each variable
+        for ( v = 0; v < g->nVars; v++ )
+        {
+            If_CluCofactors( pF, nVars, V2P[g->pVars[v]], pCof0, pCof1 );
+            nCofsBest2 = If_CluCountCofs( pCof0, nVars, g->nVars, 0, NULL );
+            if ( nCofsBest2 > 2 )
+                continue;
+            nCofsBest2 = If_CluCountCofs( pCof1, nVars, g->nVars, 0, NULL );
+            if ( nCofsBest2 > 2 )
+                continue;
+            // found good shared variable - move to the end
+            If_CluMoveVar( pF, nVars, V2P, P2V, g->pVars[v], nVars-1 );
+            for ( i = 0; i < g->nVars; i++ )
+                g->pVars[i] = P2V[nVars-g->nVars+i];
+            return 1;
+        }
+    }
+    return 0;
+}
+
+void If_CluPrintGroup( If_Grp_t * g )
+{
+    int i;
+    for ( i = 0; i < g->nVars; i++ )
+        printf( "%d ", g->pVars[i] );
+    printf( "\n" );
+    printf( "Cofs = %d", g->nMyu );
+    printf( "\n" );
+    printf( "Vars = %d", g->nVars );
+    printf( "\n" );
+}
+
+
+// finds a good var group (cof count < 6; vars are MSBs)
+If_Grp_t If_CluFindGroup( word * pF, int nVars, int iVarStart, int * V2P, int * P2V, int nBSsize, int fDisjoint )
+{
+    If_Grp_t G = {0}, * g = &G;
+    int i, r, v, nCofs, VarBest, nCofsBest2;
+    assert( nVars >= nBSsize + iVarStart && nVars <= CLU_VAR_MAX );
+    assert( nBSsize >= 3 && nBSsize <= 6 );
+    // start with the default group
+    g->nVars = nBSsize;
+    g->nMyu = If_CluCountCofs( pF, nVars, nBSsize, 0, NULL );
+    for ( i = 0; i < nBSsize; i++ )
+        g->pVars[i] = P2V[nVars-nBSsize+i];
+    // check if good enough
+    if ( g->nMyu == 2 )
+        return G;
+    if ( If_CluCheckNonDisjoint( pF, nVars, V2P, P2V, g ) )
+        return G;
+
+    printf( "Iter %d  ", -1 );
+    If_CluPrintGroup( g );
+
+    // try to find better group
+    for ( r = 0; r < nBSsize; r++ )
+    {
+        // find the best var to add
+        VarBest = P2V[nVars-1-nBSsize];
+        nCofsBest2 = If_CluCountCofs( pF, nVars, nBSsize+1, 0, NULL );
+        for ( v = nVars-2-nBSsize; v >= iVarStart; v-- )
+        {
+            If_CluMoveVar( pF, nVars, V2P, P2V, P2V[v], nVars-1-nBSsize );
+            nCofs = If_CluCountCofs( pF, nVars, nBSsize+1, 0, NULL );
+            if ( nCofsBest2 >= nCofs )
+            {
+                nCofsBest2 = nCofs;
+                VarBest = P2V[nVars-1-nBSsize];
+            }
+        }
+        // go back
+        If_CluMoveVar( pF, nVars, V2P, P2V, VarBest, nVars-1-nBSsize );
+        // update best bound set
+        nCofs = If_CluCountCofs( pF, nVars, nBSsize+1, 0, NULL );
+        assert( nCofs == nCofsBest2 );
+
+        // find the best var to remove
+        VarBest = P2V[nVars-1-nBSsize];
+        nCofsBest2 = If_CluCountCofs( pF, nVars, nBSsize, 0, NULL );
+        for ( v = nVars-nBSsize; v < nVars; v++ )
+        {
+            If_CluMoveVar( pF, nVars, V2P, P2V, P2V[v], nVars-1-nBSsize );
+            nCofs = If_CluCountCofs( pF, nVars, nBSsize, 0, NULL );
+            if ( nCofsBest2 >= nCofs )
+            {
+                nCofsBest2 = nCofs;
+                VarBest = P2V[nVars-1-nBSsize];
+            }
+        }
+
+        // go back
+        If_CluMoveVar( pF, nVars, V2P, P2V, VarBest, nVars-1-nBSsize );
+        // update best bound set
+        nCofs = If_CluCountCofs( pF, nVars, nBSsize, 0, NULL );
+        assert( nCofs == nCofsBest2 );
+        if ( g->nMyu >= nCofs )
+        {
+            g->nVars = nBSsize;
+            g->nMyu = nCofs;
+            for ( i = 0; i < nBSsize; i++ )
+                g->pVars[i] = P2V[nVars-nBSsize+i];
+        }
+
+        printf( "Iter %d  ", r );
+        If_CluPrintGroup( g );
+
+        // check if good enough
+        if ( g->nMyu == 2 )
+            return G;
+        if ( If_CluCheckNonDisjoint( pF, nVars, V2P, P2V, g ) )
+            return G;
+    }
+    assert( r == nBSsize );
+    g->nVars = 0;
+    return G;
+}
+
+
+// double check that the given group has a decomposition
+void If_CluCheckGroup( word * pTruth, int nVars, If_Grp_t * g )
+{
+    word pF[CLU_WRD_MAX];
+    int v, nCofs, V2P[CLU_VAR_MAX], P2V[CLU_VAR_MAX];
+    assert( g->nVars >= 3 && g->nVars <= 6 ); // vars
+    assert( g->nMyu >= 2 && g->nMyu <= 4 ); // cofs
+    // create permutation
+    for ( v = 0; v < nVars; v++ )
+        V2P[v] = P2V[v] = v;
+    // create truth table
+    If_CluCopy( pF, pTruth, nVars );
+    // move group up
+    If_CluMoveGroupToMsb( pF, nVars, V2P, P2V, g );
+    // check the number of cofactors
+    nCofs = If_CluCountCofs( pF, nVars, g->nVars, 0, NULL );
+    if ( nCofs != g->nMyu )
+        printf( "Group check 0 has failed.\n" );
+    // check compatible
+    if ( nCofs > 2 )
+    {
+        nCofs = If_CluCountCofs( pF, nVars-1, g->nVars-1, 0, NULL );
+        if ( nCofs > 2 )
+            printf( "Group check 1 has failed.\n" );
+        nCofs = If_CluCountCofs( pF, nVars-1, g->nVars-1, (1 << (nVars-1)), NULL );
+        if ( nCofs > 2 )
+            printf( "Group check 2 has failed.\n" );
+    }
+}
+
+
+// double check that the permutation derived is correct
+void If_CluCheckPerm( word * pTruth, word * pF, int nVars, int * V2P, int * P2V )
+{
+    int i;
+    for ( i = 0; i < nVars; i++ )
+        If_CluMoveVar( pF, nVars, V2P, P2V, i, i );
+
+    if ( If_CluEqual( pTruth, pF, nVars ) )
+        printf( "Permutation successful\n" );
+    else
+        printf( "Permutation FAILED.\n" );
+}
+
+
+
+
+static inline int If_CluSuppIsMinBase( int Supp )
+{
+    return (Supp & (Supp+1)) == 0;
+}
+static inline int If_CluHasVar( word * t, int nVars, int iVar )
+{
+    int nWords = If_CluWordNum( nVars );
+    assert( iVar < nVars );
+    if ( iVar < 6 )
+    {
+        int i, Shift = (1 << iVar);
+        for ( i = 0; i < nWords; i++ )
+            if ( (t[i] & ~Truth6[iVar]) != ((t[i] & Truth6[iVar]) >> Shift) )
+                return 1;
+        return 0;
+    }
+    else
+    {
+        int i, k, Step = (1 << (iVar - 6));
+        for ( k = 0; k < nWords; k += 2*Step )
+        {
+            for ( i = 0; i < Step; i++ )
+                if ( t[i] != t[Step+i] )
+                    return 1;
+            t += 2*Step;
+        }
+        return 0;
+    }
+}
+static inline int If_CluSupport( word * t, int nVars )
+{
+    int v, Supp = 0;
+    for ( v = 0; v < nVars; v++ )
+        if ( If_CluHasVar( t, nVars, v ) )
+            Supp |= (1 << v);
+    return Supp;
+}
+
+// returns the best group found
+If_Grp_t If_CluCheck( word * pTruth, int nVars, int nLutLeaf, int nLutRoot )
+{
+    int V2P[CLU_VAR_MAX], P2V[CLU_VAR_MAX];
+    word pF[CLU_WRD_MAX];
+    If_Grp_t G1 = {0};
+    int i, nSupp;
+    assert( nVars <= CLU_VAR_MAX );
+    assert( nVars <= nLutLeaf + nLutRoot - 1 );
+
+    // check minnimum base
+    If_CluCopy( pF, pTruth, nVars );
+    nSupp = If_CluSupport( pF, nVars );
+    if ( !nSupp || !If_CluSuppIsMinBase(nSupp) )
+        return G1;
+
+    // perform testing
+    for ( i = 0; i < nVars; i++ )
+        V2P[i] = P2V[i] = i;
+    G1 = If_CluFindGroup( pF, nVars, 0, V2P, P2V, nLutLeaf, nLutLeaf + nLutRoot == nVars + 1 );
+
+    // check permutation
+    If_CluCheckPerm( pTruth, pF, nVars, V2P, P2V );
+
+    if ( G1.nVars == 0 )
+        return G1;
+
+    // perform checking
+    If_CluCheckGroup( pTruth, nVars, &G1 );
+    return G1;
+}
+
+
+// computes delay of the decomposition
+float If_CluDelayMax( If_Grp_t * g, float * pDelays )
+{
+    float Delay = 0.0;
+    int i;
+    for ( i = 0; i < g->nVars; i++ )
+        Delay = Abc_MaxFloat( Delay, pDelays[g->pVars[i]] );
+    return Delay;
+}
+
+// returns delay of the decomposition;  sets area of the cut as its cost
+float If_CutDelayLutStruct( If_Man_t * p, If_Cut_t * pCut, char * pStr, float WireDelay )
+{
+    float Delays[CLU_VAR_MAX+2];
+    int fUsed[CLU_VAR_MAX+2] = {0};
+    If_Obj_t * pLeaf;
+    If_Grp_t G1 = {0}, G2 = {0}, G3 = {0};
+    int nLeaves = If_CutLeaveNum(pCut);
+    int i, nLutLeaf, nLutRoot;
+    // mark the cut as user cut
+    pCut->fUser = 1;
+    // quit if parameters are wrong
+    if ( strlen(pStr) != 2 )
+    {
+        printf( "Wrong LUT struct (%s)\n", pStr );
+        return ABC_INFINITY;
+    }
+    nLutLeaf = pStr[0] - '0';
+    if ( nLutLeaf < 3 || nLutLeaf > 6 )
+    {
+        printf( "Leaf size (%d) should belong to {3,4,5,6}.\n", nLutLeaf );
+        return ABC_INFINITY;
+    }
+    nLutRoot = pStr[1] - '0';
+    if ( nLutRoot < 3 || nLutRoot > 6 )
+    {
+        printf( "Leaf size (%d) should belong to {3,4,5,6}.\n", nLutRoot );
+        return ABC_INFINITY;
+    }
+    if ( nLeaves > nLutLeaf + nLutRoot - 1 )
+    {
+        printf( "The cut size (%d) is too large for the LUT structure %d%d.\n", If_CutLeaveNum(pCut), nLutLeaf, nLutRoot );
+        return ABC_INFINITY;
+    }
+
+    // remember the delays
+    If_CutForEachLeaf( p, pCut, pLeaf, i )
+        Delays[nLeaves-1-i] = If_ObjCutBest(pLeaf)->Delay;
+
+    // consider easy case
+    if ( nLeaves <= Abc_MaxInt( nLutLeaf, nLutRoot ) )
+    {
+        assert( nLeaves <= 6 );
+        for ( i = 0; i < nLeaves; i++ )
+        {
+            pCut->pPerm[i] = 1;
+            G1.pVars[i] = i;
+        }
+        G1.nVars = nLeaves;
+        pCut->Cost = 1;
+        return 1.0 + If_CluDelayMax( &G1, Delays );
+    }
+
+    // derive the first group
+    G1 = If_CluCheck( (word *)If_CutTruth(pCut), nLeaves, nLutLeaf, nLutRoot );
+    if ( G1.nVars == 0 )
+        return ABC_INFINITY;
+    // compute the delay
+    Delays[nLeaves] = If_CluDelayMax( &G1, Delays ) + (WireDelay == 0.0)?1.0:WireDelay;
+    if ( G2.nVars )
+        Delays[nLeaves+1] = If_CluDelayMax( &G2, Delays ) + (WireDelay == 0.0)?1.0:WireDelay;
+
+    // mark used groups
+    for ( i = 0; i < G1.nVars; i++ )
+        fUsed[G1.pVars[i]] = 1;
+    for ( i = 0; i < G2.nVars; i++ )
+        fUsed[G2.pVars[i]] = 1;
+    // mark unused groups
+    assert( G1.nMyu >= 2 && G1.nMyu <= 4 );
+    if ( G1.nMyu > 2 )
+        fUsed[G1.pVars[G1.nVars-1]] = 0;
+    assert( G2.nMyu >= 2 && G2.nMyu <= 4 );
+    if ( G2.nMyu > 2 )
+        fUsed[G2.pVars[G2.nVars-1]] = 0;
+
+    // create remaining group
+    assert( G3.nVars == 0 );
+    for ( i = 0; i < nLeaves; i++ )
+        if ( !fUsed[i] )
+            G3.pVars[G3.nVars++] = i;
+    G3.pVars[G3.nVars++] = nLeaves;
+    if ( G2.nVars )
+        G3.pVars[G3.nVars++] = nLeaves+1;
+    assert( G1.nVars + G2.nVars + G3.nVars == nLeaves + 
+        (G1.nVars > 0) + (G2.nVars > 0) + (G1.nMyu > 2) + (G2.nMyu > 2) );
+    // what if both non-disjoint vars are the same???
+
+    pCut->Cost = 2 + (G2.nVars > 0);
+    return 1.0 + If_CluDelayMax( &G3, Delays );
+}
+
+// testing procedure
+void If_CluTest()
+{
+//    word t = 0xff00f0f0ccccaaaa;
+    word t = 0xfedcba9876543210;
+    int nLeaves  = 6;
+    int nLutLeaf = 4;
+    int nLutRoot = 4;
+    If_Grp_t G;
+
+    G = If_CluCheck( &t, nLeaves, nLutLeaf, nLutRoot );
+
+    If_CluPrintGroup( &G );
+}
+
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
+ABC_NAMESPACE_IMPL_END
+