New ISOP computation.

src/misc/util/module.make

@@ -2,6 +2,7 @@ SRC +=  src/misc/util/utilBridge.c \
     src/misc/util/utilCex.c \
     src/misc/util/utilColor.c \
     src/misc/util/utilFile.c \
+    src/misc/util/utilIsop.c \
     src/misc/util/utilNam.c \
     src/misc/util/utilSignal.c \
     src/misc/util/utilSort.c

src/misc/util/utilIsop.c

+/**CFile****************************************************************
+
+  FileName    [utilIsop.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [ISOP computation.]
+
+  Synopsis    [ISOP computation.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - October 4, 2014.]
+
+  Revision    [$Id: utilIsop.c,v 1.00 2014/10/04 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "misc/vec/vec.h"
+#include "misc/util/utilTruth.h"
+
+ABC_NAMESPACE_IMPL_START
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef int FUNC_ISOP( word *, word *, word *, int *, int );
+
+static FUNC_ISOP Abc_Isop7Cover; 
+static FUNC_ISOP Abc_Isop8Cover;
+static FUNC_ISOP Abc_Isop9Cover; 
+static FUNC_ISOP Abc_Isop10Cover;
+static FUNC_ISOP Abc_Isop11Cover;
+static FUNC_ISOP Abc_Isop12Cover;
+static FUNC_ISOP Abc_Isop13Cover;
+static FUNC_ISOP Abc_Isop14Cover;
+static FUNC_ISOP Abc_Isop15Cover;
+static FUNC_ISOP Abc_Isop16Cover;
+
+static FUNC_ISOP * s_pFuncIsopCover[17] =
+{
+    NULL, // 0
+    NULL, // 1
+    NULL, // 2
+    NULL, // 3
+    NULL, // 4
+    NULL, // 5
+    NULL, // 6
+    Abc_Isop7Cover,  // 7
+    Abc_Isop8Cover,  // 8
+    Abc_Isop9Cover,  // 9
+    Abc_Isop10Cover, // 10
+    Abc_Isop11Cover, // 11
+    Abc_Isop12Cover, // 12
+    Abc_Isop13Cover, // 13
+    Abc_Isop14Cover, // 14
+    Abc_Isop15Cover, // 15
+    Abc_Isop16Cover  // 16
+};
+
+extern int Abc_IsopCheck( word * pOn, word * pOnDc, word * pRes, int nVars, int nCostLim, int * pCover );
+extern int Abc_EsopCheck( word * pOn, int nVars, int nCostLim, int * pCover );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [These procedures assume that function has exact support.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Abc_IsopAddLits( int * pCover, int nCost0, int nCost1, int Var )
+{
+    int c;
+    if ( pCover == NULL ) return;
+    for ( c = 0; c < nCost0; c++ )
+        pCover[c] |= (1 << Abc_Var2Lit(Var,0));
+    for ( c = 0; c < nCost1; c++ )
+        pCover[nCost0+c] |= (1 << Abc_Var2Lit(Var,1));
+}
+int Abc_Isop6Cover( word uOn, word uOnDc, word * pRes, int nVars, int nCostLim, int * pCover )
+{
+    word uOn0, uOn1, uOnDc0, uOnDc1, uRes0, uRes1, uRes2;
+    int Var, nCost0, nCost1, nCost2;
+    assert( nVars <= 6 );
+    assert( (uOn & ~uOnDc) == 0 );
+    if ( uOn == 0 )
+    {
+        pRes[0] = 0;
+        return 0;
+    }
+    if ( uOnDc == ~(word)0 )
+    {
+        pRes[0] = ~(word)0;
+        if ( pCover ) pCover[0] = 0;
+        return (1 << 16);
+    }
+    assert( nVars > 0 );
+    // find the topmost var
+    for ( Var = nVars-1; Var >= 0; Var-- )
+        if ( Abc_Tt6HasVar( uOn, Var ) || Abc_Tt6HasVar( uOnDc, Var ) )
+             break;
+    assert( Var >= 0 );
+    // cofactor
+    uOn0   = Abc_Tt6Cofactor0( uOn,   Var );
+    uOn1   = Abc_Tt6Cofactor1( uOn  , Var );
+    uOnDc0 = Abc_Tt6Cofactor0( uOnDc, Var );
+    uOnDc1 = Abc_Tt6Cofactor1( uOnDc, Var );
+    // solve for cofactors
+    nCost0 = Abc_Isop6Cover( uOn0 & ~uOnDc1, uOnDc0, &uRes0, Var, nCostLim, pCover );
+    if ( nCost0 >= nCostLim ) return nCostLim;
+    nCost1 = Abc_Isop6Cover( uOn1 & ~uOnDc0, uOnDc1, &uRes1, Var, nCostLim, pCover ? pCover + (nCost0 >> 16) : NULL );
+    if ( nCost0 + nCost1 >= nCostLim ) return nCostLim;
+    nCost2 = Abc_Isop6Cover( (uOn0 & ~uRes0) | (uOn1 & ~uRes1), uOnDc0 & uOnDc1, &uRes2, Var, nCostLim, pCover ? pCover + (nCost0 >> 16) + (nCost1 >> 16) : NULL );
+    if ( nCost0 + nCost1 + nCost2 >= nCostLim ) return nCostLim;
+    // derive the final truth table
+    *pRes = uRes2 | (uRes0 & s_Truths6Neg[Var]) | (uRes1 & s_Truths6[Var]);
+    assert( (uOn & ~*pRes) == 0 && (*pRes & ~uOnDc) == 0 );
+    Abc_IsopAddLits( pCover, nCost0, nCost1, Var );
+    return nCost0 + nCost1 + nCost2 + (nCost0 >> 16) + (nCost1 >> 16);
+}
+int Abc_Isop7Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    word uOn0, uOn1, uOn2, uOnDc2, uRes0, uRes1, uRes2;
+    int nCost0, nCost1, nCost2, nVars = 6;
+    // cofactor
+    uOn0 = pOn[0] & ~pOnDc[1];
+    uOn1 = pOn[1] & ~pOnDc[0];
+    // solve for cofactors
+    nCost0 = Abc_IsopCheck( &uOn0, pOnDc,   &uRes0, nVars, nCostLim, pCover );
+    if ( nCost0 >= nCostLim ) return nCostLim;
+    nCost1 = Abc_IsopCheck( &uOn1, pOnDc+1, &uRes1, nVars, nCostLim, pCover ? pCover + (nCost0 >> 16) : NULL );
+    if ( nCost0 + nCost1 >= nCostLim ) return nCostLim;
+    uOn2 = (pOn[0] & ~uRes0) | (pOn[1] & ~uRes1);
+    uOnDc2 = pOnDc[0] & pOnDc[1];
+    nCost2 = Abc_IsopCheck( &uOn2, &uOnDc2,  &uRes2, nVars, nCostLim, pCover ? pCover + (nCost0 >> 16) + (nCost1 >> 16) : NULL );
+    if ( nCost0 + nCost1 + nCost2 >= nCostLim ) return nCostLim;
+    // derive the final truth table
+    pRes[0] = uRes2 | uRes0;
+    pRes[1] = uRes2 | uRes1;
+    assert( (pOn[0] & ~pRes[0]) == 0 && (pRes[0] & ~pOnDc[0]) == 0 );
+    assert( (pOn[1] & ~pRes[1]) == 0 && (pRes[1] & ~pOnDc[1]) == 0 );
+    Abc_IsopAddLits( pCover, nCost0, nCost1, nVars );
+    return nCost0 + nCost1 + nCost2 + (nCost0 >> 16) + (nCost1 >> 16);
+}
+int Abc_Isop8Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    word uOn0[2], uOn1[2], uOn2[2], uOnDc2[2], uRes0[2], uRes1[2], uRes2[2];
+    int nCost0, nCost1, nCost2, nVars = 7;
+    // cofactor
+    uOn0[0] = pOn[0] & ~pOnDc[2];
+    uOn0[1] = pOn[1] & ~pOnDc[3];
+    uOn1[0] = pOn[2] & ~pOnDc[0];
+    uOn1[1] = pOn[3] & ~pOnDc[1];
+    // solve for cofactors
+    nCost0 = Abc_IsopCheck( uOn0, pOnDc,   uRes0, nVars, nCostLim, pCover );
+    if ( nCost0 >= nCostLim ) return nCostLim;
+    nCost1 = Abc_IsopCheck( uOn1, pOnDc+2, uRes1, nVars, nCostLim, pCover ? pCover + (nCost0 >> 16) : NULL );
+    if ( nCost0 + nCost1 >= nCostLim ) return nCostLim;
+    uOn2[0] = (pOn[0] & ~uRes0[0]) | (pOn[2] & ~uRes1[0]);
+    uOn2[1] = (pOn[1] & ~uRes0[1]) | (pOn[3] & ~uRes1[1]);
+    uOnDc2[0] = pOnDc[0] & pOnDc[2];
+    uOnDc2[1] = pOnDc[1] & pOnDc[3];
+    nCost2 = Abc_IsopCheck( uOn2, uOnDc2,  uRes2, nVars, nCostLim, pCover ? pCover + (nCost0 >> 16) + (nCost1 >> 16) : NULL );
+    if ( nCost0 + nCost1 + nCost2 >= nCostLim ) return nCostLim;
+    // derive the final truth table
+    pRes[0] = uRes2[0] | uRes0[0];
+    pRes[1] = uRes2[1] | uRes0[1];
+    pRes[2] = uRes2[0] | uRes1[0];
+    pRes[3] = uRes2[1] | uRes1[1];
+    assert( (pOn[0] & ~pRes[0]) == 0 && (pOn[1] & ~pRes[1]) == 0 && (pOn[2] & ~pRes[2]) == 0 && (pOn[3] & ~pRes[3]) == 0 );
+    assert( (pRes[0] & ~pOnDc[0])==0 && (pRes[1] & ~pOnDc[1])==0 && (pRes[2] & ~pOnDc[2])==0 && (pRes[3] & ~pOnDc[3])==0 );
+    Abc_IsopAddLits( pCover, nCost0, nCost1, nVars );
+    return nCost0 + nCost1 + nCost2 + (nCost0 >> 16) + (nCost1 >> 16);
+}
+int Abc_Isop9Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    word uOn0[4], uOn1[4], uOn2[4], uOnDc2[4], uRes0[4], uRes1[4], uRes2[4];
+    int c, nCost0, nCost1, nCost2, nVars = 8, nWords = 4;
+    // cofactor
+    for ( c = 0; c < nWords; c++ )
+        uOn0[c] = pOn[c] & ~pOnDc[c+nWords], uOn1[c] = pOn[c+nWords] & ~pOnDc[c];
+    // solve for cofactors
+    nCost0 = Abc_IsopCheck( uOn0, pOnDc,        uRes0, nVars, nCostLim, pCover );
+    if ( nCost0 >= nCostLim ) return nCostLim;
+    nCost1 = Abc_IsopCheck( uOn1, pOnDc+nWords, uRes1, nVars, nCostLim, pCover ? pCover + (nCost0 >> 16) : NULL );
+    if ( nCost0 + nCost1 >= nCostLim ) return nCostLim;
+    for ( c = 0; c < nWords; c++ )
+        uOn2[c] = (pOn[c] & ~uRes0[c]) | (pOn[c+nWords] & ~uRes1[c]), uOnDc2[c] = pOnDc[c] & pOnDc[c+nWords];
+    nCost2 = Abc_IsopCheck( uOn2, uOnDc2,       uRes2, nVars, nCostLim, pCover ? pCover + (nCost0 >> 16) + (nCost1 >> 16) : NULL );
+    if ( nCost0 + nCost1 + nCost2 >= nCostLim ) return nCostLim;
+    // derive the final truth table
+    for ( c = 0; c < nWords; c++ )
+        pRes[c] = uRes2[c] | uRes0[c], pRes[c+nWords] = uRes2[c] | uRes1[c];
+    // verify
+    for ( c = 0; c < (nWords<<1); c++ )
+        assert( (pOn[c]  & ~pRes[c] ) == 0 && (pRes[c] & ~pOnDc[c]) == 0 );
+    Abc_IsopAddLits( pCover, nCost0, nCost1, nVars );
+    return nCost0 + nCost1 + nCost2 + (nCost0 >> 16) + (nCost1 >> 16);
+}
+int Abc_Isop10Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    return 0;
+}
+int Abc_Isop11Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    return 0;
+}
+int Abc_Isop12Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    return 0;
+}
+int Abc_Isop13Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    return 0;
+}
+int Abc_Isop14Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    return 0;
+}
+int Abc_Isop15Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    return 0;
+}
+int Abc_Isop16Cover( word * pOn, word * pOnDc, word * pRes, int * pCover, int nCostLim )
+{
+    return 0;
+}
+int Abc_IsopCheck( word * pOn, word * pOnDc, word * pRes, int nVars, int nCostLim, int * pCover )
+{
+    int Var;
+    for ( Var = nVars - 1; Var > 6; Var-- )
+        if ( Abc_TtHasVar( pOn, nVars, Var ) || Abc_TtHasVar( pOnDc, nVars, Var ) )
+            return s_pFuncIsopCover[Var+1]( pOn, pOnDc, pRes, pCover, nCostLim );
+    return Abc_Isop6Cover( *pOn, *pOnDc, pRes, nVars, nCostLim, pCover );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compute CNF assuming it does not exceed the limit.]
+
+  Description [Please note that pCover should have at least 32 extra entries!]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_IsopCnf( word * pFunc, int nVars, int nCubeLim, int * pCover )
+{
+    word pRes[1024];
+    int c, Cost0, Cost1, CostLim = nCubeLim << 16;
+    assert( Abc_TtHasVar( pFunc, nVars, nVars - 1 ) );
+    if ( nVars > 6 )
+        Cost0 = s_pFuncIsopCover[nVars]( pFunc, pFunc, pRes, pCover, CostLim );
+    else
+        Cost0 = Abc_Isop6Cover( *pFunc, *pFunc, pRes, nVars, CostLim, pCover );
+    if ( Cost0 >= CostLim )
+        return CostLim;
+    Abc_TtNot( pFunc, Abc_TtWordNum(nVars) );
+    if ( nVars > 6 )
+        Cost1 = s_pFuncIsopCover[nVars]( pFunc, pFunc, pRes, pCover ? pCover + (Cost0 >> 16) : NULL, CostLim );
+    else
+        Cost1 = Abc_Isop6Cover( *pFunc, *pFunc, pRes, nVars, CostLim, pCover ? pCover + (Cost0 >> 16) : NULL );
+    Abc_TtNot( pFunc, Abc_TtWordNum(nVars) );
+    if ( Cost0 + Cost1 >= CostLim )
+        return CostLim;
+    if ( pCover == NULL )
+        return Cost0 + Cost1;
+    for ( c = 0; c < (Cost0 >> 16); c++ )
+        pCover[c] |= (1 << Abc_Var2Lit(nVars, 0));
+    for ( c = 0; c < (Cost1 >> 16); c++ )
+        pCover[c+(Cost0 >> 16)] |= (1 << Abc_Var2Lit(nVars, 1));
+    return Cost0 + Cost1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [These procedures assume that function has exact support.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Abc_EsopAddLits( int * pCover, int Max, int r0, int r1, int r2, int Var )
+{
+    int i;
+    if ( pCover == NULL ) return;
+    r0 >>= 16;
+    r1 >>= 16;
+    r2 >>= 16;
+    if ( Max == r0 )
+    {
+        for ( i = 0; i < r1; i++ )
+            pCover[i] = pCover[r0+i];
+        for ( i = 0; i < r2; i++ )
+            pCover[r1+i] = pCover[r0+r1+i] | (1 << Abc_Var2Lit(Var,0));
+    }
+    else if ( Max == r1 )
+    {
+        for ( i = 0; i < r2; i++ )
+            pCover[r0+i] = pCover[r0+r1+i] | (1 << Abc_Var2Lit(Var,1));
+    }
+    else
+    {
+        for ( i = 0; i < r0; i++ )
+            pCover[i] |= (1 << Abc_Var2Lit(Var,0));
+        for ( i = 0; i < r1; i++ )
+            pCover[r0+i] |= (1 << Abc_Var2Lit(Var,1));
+    }
+}
+int Abc_Esop6Cover( word t, int nVars, int nCostLim, int * pCover )
+{
+    word c0, c1;
+    int Var, r0, r1, r2, Max;
+    assert( nVars <= 6 );
+    if ( t == 0 )
+        return 0;
+    if ( t == ~(word)0 )
+    {
+        if ( pCover ) *pCover = 0;
+        return 1 << 16;
+    }
+    assert( nVars > 0 );
+    // find the topmost var
+    for ( Var = nVars-1; Var >= 0; Var-- )
+        if ( Abc_Tt6HasVar( t, Var ) )
+             break;
+    assert( Var >= 0 );
+    // cofactor
+    c0 = Abc_Tt6Cofactor0( t, Var );
+    c1 = Abc_Tt6Cofactor1( t, Var );
+    // call recursively
+    r0 = Abc_Esop6Cover( c0,      Var, nCostLim, pCover ? pCover : NULL );
+    if ( r0 >= nCostLim ) return nCostLim;
+    r1 = Abc_Esop6Cover( c1,      Var, nCostLim, pCover ? pCover + (r0 >> 16) : NULL );
+    if ( r1 >= nCostLim ) return nCostLim;
+    r2 = Abc_Esop6Cover( c0 ^ c1, Var, nCostLim, pCover ? pCover + (r0 >> 16) + (r1 >> 16) : NULL );
+    if ( r2 >= nCostLim ) return nCostLim;
+    Max = Abc_MaxInt( r0, Abc_MaxInt(r1, r2) );
+    if ( r0 + r1 + r2 - Max >= nCostLim ) return nCostLim;
+    // add literals
+    Abc_EsopAddLits( pCover, Max, r0, r1, r2, Var );
+    return r0 + r1 + r2 - Max;
+}
+int Abc_EsopCover( word * pOn, int nVars, int nCostLim, int * pCover )
+{
+    int c, r0, r1, r2, Max, nWords = (1 << (nVars - 7));
+    assert( nVars > 6 );
+    r0 = Abc_EsopCheck( pOn,   nVars-1, nCostLim, pCover );
+    if ( r0 >= nCostLim ) return nCostLim;
+    r1 = Abc_EsopCheck( pOn+1, nVars-1, nCostLim, pCover ? pCover + (r0 >> 16) : NULL );
+    if ( r1 >= nCostLim ) return nCostLim;
+    for ( c = 0; c < nWords; c++ )
+        pOn[c] ^= pOn[nWords+c];
+    r2 = Abc_EsopCheck( pOn, nVars-1, nCostLim, pCover ? pCover + (r0 >> 16) + (r1 >> 16) : NULL );
+    for ( c = 0; c < nWords; c++ )
+        pOn[c] ^= pOn[nWords+c];
+    if ( r2 >= nCostLim ) return nCostLim;
+    Max = Abc_MaxInt( r0, Abc_MaxInt(r1, r2) );
+    if ( r0 + r1 + r2 - Max >= nCostLim ) return nCostLim;
+    // add literals
+    Abc_EsopAddLits( pCover, Max, r0, r1, r2, nVars-1 );
+    return r0 + r1 + r2 - Max;
+}
+int Abc_EsopCheck( word * pOn, int nVars, int nCostLim, int * pCover )
+{
+    int Var;
+    for ( Var = nVars - 1; Var > 6; Var-- )
+        if ( Abc_TtHasVar( pOn, nVars, Var ) )
+            return Abc_EsopCover( pOn, Var + 1, nCostLim, pCover );
+    return Abc_Esop6Cover( *pOn, nVars, nCostLim, pCover );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [This procedure assumes that function has exact support.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+#define ABC_ISOP_MAX_VAR 12
+static inline word ** Abc_IsopTtElems()
+{
+    static word TtElems[ABC_ISOP_MAX_VAR+1][ABC_ISOP_MAX_VAR > 6 ? (1 << (ABC_ISOP_MAX_VAR-6)) : 1], * pTtElems[ABC_ISOP_MAX_VAR+1] = {NULL};
+    if ( pTtElems[0] == NULL )
+    {
+        int v;
+        for ( v = 0; v <= ABC_ISOP_MAX_VAR; v++ )
+            pTtElems[v] = TtElems[v];
+        Abc_TtElemInit( pTtElems, ABC_ISOP_MAX_VAR );
+    }
+    return pTtElems;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Create truth table for the given cover.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_IsopBuildTruth( Vec_Int_t * vCover, int nVars, word * pRes, int fXor, int fCompl )
+{
+    word ** pTtElems = Abc_IsopTtElems();
+    word pCube[1024];
+    int nWords = Abc_TtWordNum( nVars );
+    int c, v, Cube;
+    Abc_TtClear( pRes, nWords );
+    Vec_IntForEachEntry( vCover, Cube, c )
+    {
+        Abc_TtFill( pCube, nWords );
+        for ( v = 0; v < nVars; v++ )
+            if ( ((Cube >> (v << 1)) & 3) == 1 )
+                Abc_TtSharp( pCube, pCube, pTtElems[v], nWords );
+            else if ( ((Cube >> (v << 1)) & 3) == 2 )
+                Abc_TtAnd( pCube, pCube, pTtElems[v], nWords, 0 );
+        if ( fXor )
+            Abc_TtXor( pRes, pRes, pCube, nWords, 0 );
+        else
+            Abc_TtOr( pRes, pRes, pCube, nWords );
+    }
+    if ( fCompl )
+        Abc_TtNot( pRes, nWords );
+}
+static inline void Abc_IsopVerify( word * pFunc, int nVars, word * pRes, Vec_Int_t * vCover, int fXor, int fCompl )
+{
+    Abc_IsopBuildTruth( vCover, nVars, pRes, fXor, fCompl );
+    if ( !Abc_TtEqual( pFunc, pRes, Abc_TtWordNum(nVars) ) )
+        printf( "Verification failed.\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [This procedure assumes that function has exact support.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_Isop( word * pFunc, int nVars, int Type, int nCubeLim, Vec_Int_t * vCover )
+{
+    word pRes[1024];
+    int Limit = nCubeLim ? nCubeLim : 0xFFFF; 
+    int LimitXor = nCubeLim ? 3 * Limit : 3 * (nVars + 1); 
+    int nCost0 = -1, nCost1 = -1, nCost2 = -1;
+    assert( nVars <= 16 );
+    assert( Abc_TtHasVar( pFunc, nVars, nVars - 1 ) );
+    assert( !(Type & 4) );
+    // xor polarity
+    if ( Type & 4 )
+        nCost2 = Abc_EsopCheck( pFunc, nVars, LimitXor << 16, NULL );
+    // direct polarity
+    if ( Type & 1 )
+        nCost0 = Abc_IsopCheck( pFunc, pFunc, pRes, nVars, Abc_MinInt(Limit, 3*nCost2) << 16, NULL );
+    // opposite polarity
+    if ( Type & 2 )
+    {
+        Abc_TtNot( pFunc, Abc_TtWordNum(nVars) );
+        nCost1 = Abc_IsopCheck( pFunc, pFunc, pRes, nVars, Abc_MinInt(nCost0, Abc_MinInt(Limit, 3*nCost2)) << 16, NULL );
+        Abc_TtNot( pFunc, Abc_TtWordNum(nVars) );
+    }
+    assert( nCost0 >= 0 || nCost1 >= 0 );
+    // find minimum cover
+    if ( nCost0 <= nCost1 || nCost0 != -1 )
+    {
+        Vec_IntFill( vCover, -1, nCost0 >> 16 );
+        Abc_IsopCheck( pFunc, pFunc, pRes, nVars, ABC_INFINITY, Vec_IntArray(vCover) );
+        Abc_IsopVerify( pFunc, nVars, pRes, vCover, 0, 0 );
+        return 0;
+    }
+    if ( nCost1 < nCost0 || nCost1 != -1 )
+    {
+        Vec_IntFill( vCover, -1, nCost1 >> 16 );
+        Abc_TtNot( pFunc, Abc_TtWordNum(nVars) );
+        Abc_IsopCheck( pFunc, pFunc, pRes, nVars, ABC_INFINITY, Vec_IntArray(vCover) );
+        Abc_TtNot( pFunc, Abc_TtWordNum(nVars) );
+        Abc_IsopVerify( pFunc, nVars, pRes, vCover, 0, 1 );
+        return 1;
+    }
+    assert( 0 );
+    return -1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
+ABC_NAMESPACE_IMPL_END
+