cuddClip.c

Go to the documentation of this file.

/**CFile***********************************************************************

  FileName    [cuddClip.c]

  PackageName [cudd]

  Synopsis    [Clipping functions.]

  Description [External procedures included in this module:
                <ul>
                <li> Cudd_bddClippingAnd()
                <li> Cudd_bddClippingAndAbstract()
                </ul>
       Internal procedures included in this module:
                <ul>
                <li> cuddBddClippingAnd()
                <li> cuddBddClippingAndAbstract()
                </ul>
       Static procedures included in this module:
                <ul>
                <li> cuddBddClippingAndRecur()
                <li> cuddBddClipAndAbsRecur()
                </ul>

  SeeAlso     []

  Author      [Fabio Somenzi]

  Copyright   [Copyright (c) 1995-2004, Regents of the University of Colorado

  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions
  are met:

  Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.

  Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.

  Neither the name of the University of Colorado nor the names of its
  contributors may be used to endorse or promote products derived from
  this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  POSSIBILITY OF SUCH DAMAGE.]

******************************************************************************/

#include "misc/util/util_hack.h"
#include "cuddInt.h"

ABC_NAMESPACE_IMPL_START




/*---------------------------------------------------------------------------*/
/* Constant declarations                                                     */
/*---------------------------------------------------------------------------*/


/*---------------------------------------------------------------------------*/
/* Stucture declarations                                                     */
/*---------------------------------------------------------------------------*/


/*---------------------------------------------------------------------------*/
/* Type declarations                                                         */
/*---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------*/
/* Variable declarations                                                     */
/*---------------------------------------------------------------------------*/

#ifndef lint
static char rcsid[] DD_UNUSED = "$Id: cuddClip.c,v 1.8 2004/08/13 18:04:47 fabio Exp $";
#endif

/*---------------------------------------------------------------------------*/
/* Macro declarations                                                        */
/*---------------------------------------------------------------------------*/


/**AutomaticStart*************************************************************/

/*---------------------------------------------------------------------------*/
/* Static function prototypes                                                */
/*---------------------------------------------------------------------------*/

static DdNode * cuddBddClippingAndRecur (DdManager *manager, DdNode *f, DdNode *g, int distance, int direction);
static DdNode * cuddBddClipAndAbsRecur (DdManager *manager, DdNode *f, DdNode *g, DdNode *cube, int distance, int direction);

/**AutomaticEnd***************************************************************/


/*---------------------------------------------------------------------------*/
/* Definition of exported functions                                          */
/*---------------------------------------------------------------------------*/


/**Function********************************************************************

  Synopsis    [Approximates the conjunction of two BDDs f and g.]

  Description [Approximates the conjunction of two BDDs f and g. Returns a
  pointer to the resulting BDD if successful; NULL if the intermediate
  result blows up.]

  SideEffects [None]

  SeeAlso     [Cudd_bddAnd]

******************************************************************************/
DdNode *
Cudd_bddClippingAnd(
  DdManager * dd /* manager */,
  DdNode * f /* first conjunct */,
  DdNode * g /* second conjunct */,
  int  maxDepth /* maximum recursion depth */,
  int  direction /* under (0) or over (1) approximation */)
{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddClippingAnd(dd,f,g,maxDepth,direction);
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_bddClippingAnd */


/**Function********************************************************************

  Synopsis    [Approximates the conjunction of two BDDs f and g and
  simultaneously abstracts the variables in cube.]

  Description [Approximates the conjunction of two BDDs f and g and
  simultaneously abstracts the variables in cube. The variables are
  existentially abstracted. Returns a pointer to the resulting BDD if
  successful; NULL if the intermediate result blows up.]

  SideEffects [None]

  SeeAlso     [Cudd_bddAndAbstract Cudd_bddClippingAnd]

******************************************************************************/
DdNode *
Cudd_bddClippingAndAbstract(
  DdManager * dd /* manager */,
  DdNode * f /* first conjunct */,
  DdNode * g /* second conjunct */,
  DdNode * cube /* cube of variables to be abstracted */,
  int  maxDepth /* maximum recursion depth */,
  int  direction /* under (0) or over (1) approximation */)
{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddClippingAndAbstract(dd,f,g,cube,maxDepth,direction);
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_bddClippingAndAbstract */


/*---------------------------------------------------------------------------*/
/* Definition of internal functions                                          */
/*---------------------------------------------------------------------------*/


/**Function********************************************************************

  Synopsis    [Approximates the conjunction of two BDDs f and g.]

  Description [Approximates the conjunction of two BDDs f and g. Returns a
  pointer to the resulting BDD if successful; NULL if the intermediate
  result blows up.]

  SideEffects [None]

  SeeAlso     [Cudd_bddClippingAnd]

******************************************************************************/
DdNode *
cuddBddClippingAnd(
  DdManager * dd /* manager */,
  DdNode * f /* first conjunct */,
  DdNode * g /* second conjunct */,
  int  maxDepth /* maximum recursion depth */,
  int  direction /* under (0) or over (1) approximation */)
{
    DdNode *res;

    res = cuddBddClippingAndRecur(dd,f,g,maxDepth,direction);

    return(res);

} /* end of cuddBddClippingAnd */


/**Function********************************************************************

  Synopsis    [Approximates the conjunction of two BDDs f and g and
  simultaneously abstracts the variables in cube.]

  Description [Approximates the conjunction of two BDDs f and g and
  simultaneously abstracts the variables in cube. Returns a
  pointer to the resulting BDD if successful; NULL if the intermediate
  result blows up.]

  SideEffects [None]

  SeeAlso     [Cudd_bddClippingAndAbstract]

******************************************************************************/
DdNode *
cuddBddClippingAndAbstract(
  DdManager * dd /* manager */,
  DdNode * f /* first conjunct */,
  DdNode * g /* second conjunct */,
  DdNode * cube /* cube of variables to be abstracted */,
  int  maxDepth /* maximum recursion depth */,
  int  direction /* under (0) or over (1) approximation */)
{
    DdNode *res;

    res = cuddBddClipAndAbsRecur(dd,f,g,cube,maxDepth,direction);

    return(res);

} /* end of cuddBddClippingAndAbstract */


/*---------------------------------------------------------------------------*/
/* Definition of static functions                                            */
/*---------------------------------------------------------------------------*/


/**Function********************************************************************

  Synopsis [Implements the recursive step of Cudd_bddClippingAnd.]

  Description [Implements the recursive step of Cudd_bddClippingAnd by taking
  the conjunction of two BDDs.  Returns a pointer to the result is
  successful; NULL otherwise.]

  SideEffects [None]

  SeeAlso     [cuddBddClippingAnd]

******************************************************************************/
static DdNode *
cuddBddClippingAndRecur(
  DdManager * manager,
  DdNode * f,
  DdNode * g,
  int  distance,
  int  direction)
{
    DdNode *F, *ft, *fe, *G, *gt, *ge;
    DdNode *one, *zero, *r, *t, *e;
    unsigned int topf, topg, index;
    DD_CTFP cacheOp;

    statLine(manager);
    one = DD_ONE(manager);
    zero = Cudd_Not(one);

    /* Terminal cases. */
    if (f == zero || g == zero || f == Cudd_Not(g)) return(zero);
    if (f == g || g == one) return(f);
    if (f == one) return(g);
    if (distance == 0) {
        /* One last attempt at returning the right result. We sort of
        ** cheat by calling Cudd_bddLeq. */
        if (Cudd_bddLeq(manager,f,g)) return(f);
        if (Cudd_bddLeq(manager,g,f)) return(g);
        if (direction == 1) {
            if (Cudd_bddLeq(manager,f,Cudd_Not(g)) ||
                Cudd_bddLeq(manager,g,Cudd_Not(f))) return(zero);
        }
        return(Cudd_NotCond(one,(direction == 0)));
    }

    /* At this point f and g are not constant. */
    distance--;

    /* Check cache. Try to increase cache efficiency by sorting the
    ** pointers. */
    if (f > g) {
        DdNode *tmp = f;
        f = g; g = tmp;
    }
    F = Cudd_Regular(f);
    G = Cudd_Regular(g);
    cacheOp = (DD_CTFP)
        (direction ? Cudd_bddClippingAnd : cuddBddClippingAnd);
    if (F->ref != 1 || G->ref != 1) {
        r = cuddCacheLookup2(manager, cacheOp, f, g);
        if (r != NULL) return(r);
    }

    /* Here we can skip the use of cuddI, because the operands are known
    ** to be non-constant.
    */
    topf = manager->perm[F->index];
    topg = manager->perm[G->index];

    /* Compute cofactors. */
    if (topf <= topg) {
        index = F->index;
        ft = cuddT(F);
        fe = cuddE(F);
        if (Cudd_IsComplement(f)) {
            ft = Cudd_Not(ft);
            fe = Cudd_Not(fe);
        }
    } else {
        index = G->index;
        ft = fe = f;
    }

    if (topg <= topf) {
        gt = cuddT(G);
        ge = cuddE(G);
        if (Cudd_IsComplement(g)) {
            gt = Cudd_Not(gt);
            ge = Cudd_Not(ge);
        }
    } else {
        gt = ge = g;
    }

    t = cuddBddClippingAndRecur(manager, ft, gt, distance, direction);
    if (t == NULL) return(NULL);
    cuddRef(t);
    e = cuddBddClippingAndRecur(manager, fe, ge, distance, direction);
    if (e == NULL) {
        Cudd_RecursiveDeref(manager, t);
        return(NULL);
    }
    cuddRef(e);

    if (t == e) {
        r = t;
    } else {
        if (Cudd_IsComplement(t)) {
            r = cuddUniqueInter(manager,(int)index,Cudd_Not(t),Cudd_Not(e));
            if (r == NULL) {
                Cudd_RecursiveDeref(manager, t);
                Cudd_RecursiveDeref(manager, e);
                return(NULL);
            }
            r = Cudd_Not(r);
        } else {
            r = cuddUniqueInter(manager,(int)index,t,e);
            if (r == NULL) {
                Cudd_RecursiveDeref(manager, t);
                Cudd_RecursiveDeref(manager, e);
                return(NULL);
            }
        }
    }
    cuddDeref(e);
    cuddDeref(t);
    if (F->ref != 1 || G->ref != 1)
        cuddCacheInsert2(manager, cacheOp, f, g, r);
    return(r);

} /* end of cuddBddClippingAndRecur */


/**Function********************************************************************

  Synopsis [Approximates the AND of two BDDs and simultaneously abstracts the
  variables in cube.]

  Description [Approximates the AND of two BDDs and simultaneously
  abstracts the variables in cube. The variables are existentially
  abstracted.  Returns a pointer to the result is successful; NULL
  otherwise.]

  SideEffects [None]

  SeeAlso     [Cudd_bddClippingAndAbstract]

******************************************************************************/
static DdNode *
cuddBddClipAndAbsRecur(
  DdManager * manager,
  DdNode * f,
  DdNode * g,
  DdNode * cube,
  int  distance,
  int  direction)
{
    DdNode *F, *ft, *fe, *G, *gt, *ge;
    DdNode *one, *zero, *r, *t, *e, *Cube;
    unsigned int topf, topg, topcube, top, index;
    ptruint cacheTag;

    statLine(manager);
    one = DD_ONE(manager);
    zero = Cudd_Not(one);

    /* Terminal cases. */
    if (f == zero || g == zero || f == Cudd_Not(g)) return(zero);
    if (f == one && g == one)   return(one);
    if (cube == one) {
        return(cuddBddClippingAndRecur(manager, f, g, distance, direction));
    }
    if (f == one || f == g) {
        return (cuddBddExistAbstractRecur(manager, g, cube));
    }
    if (g == one) {
        return (cuddBddExistAbstractRecur(manager, f, cube));
    }
    if (distance == 0) return(Cudd_NotCond(one,(direction == 0)));

    /* At this point f, g, and cube are not constant. */
    distance--;

    /* Check cache. */
    if (f > g) { /* Try to increase cache efficiency. */
        DdNode *tmp = f;
        f = g; g = tmp;
    }
    F = Cudd_Regular(f);
    G = Cudd_Regular(g);
    cacheTag = direction ? DD_BDD_CLIPPING_AND_ABSTRACT_UP_TAG :
        DD_BDD_CLIPPING_AND_ABSTRACT_DOWN_TAG;
    if (F->ref != 1 || G->ref != 1) {
        r = cuddCacheLookup(manager, cacheTag,
                            f, g, cube);
        if (r != NULL) {
            return(r);
        }
    }

    /* Here we can skip the use of cuddI, because the operands are known
    ** to be non-constant.
    */
    topf = manager->perm[F->index];
    topg = manager->perm[G->index];
    top = ddMin(topf, topg);
    topcube = manager->perm[cube->index];

    if (topcube < top) {
        return(cuddBddClipAndAbsRecur(manager, f, g, cuddT(cube),
                                      distance, direction));
    }
    /* Now, topcube >= top. */

    if (topf == top) {
        index = F->index;
        ft = cuddT(F);
        fe = cuddE(F);
        if (Cudd_IsComplement(f)) {
            ft = Cudd_Not(ft);
            fe = Cudd_Not(fe);
        }
    } else {
        index = G->index;
        ft = fe = f;
    }

    if (topg == top) {
        gt = cuddT(G);
        ge = cuddE(G);
        if (Cudd_IsComplement(g)) {
            gt = Cudd_Not(gt);
            ge = Cudd_Not(ge);
        }
    } else {
        gt = ge = g;
    }

    if (topcube == top) {
        Cube = cuddT(cube);
    } else {
        Cube = cube;
    }

    t = cuddBddClipAndAbsRecur(manager, ft, gt, Cube, distance, direction);
    if (t == NULL) return(NULL);

    /* Special case: 1 OR anything = 1. Hence, no need to compute
    ** the else branch if t is 1.
    */
    if (t == one && topcube == top) {
        if (F->ref != 1 || G->ref != 1)
            cuddCacheInsert(manager, cacheTag, f, g, cube, one);
        return(one);
    }
    cuddRef(t);

    e = cuddBddClipAndAbsRecur(manager, fe, ge, Cube, distance, direction);
    if (e == NULL) {
        Cudd_RecursiveDeref(manager, t);
        return(NULL);
    }
    cuddRef(e);

    if (topcube == top) {       /* abstract */
        r = cuddBddClippingAndRecur(manager, Cudd_Not(t), Cudd_Not(e),
                                    distance, (direction == 0));
        if (r == NULL) {
            Cudd_RecursiveDeref(manager, t);
            Cudd_RecursiveDeref(manager, e);
            return(NULL);
        }
        r = Cudd_Not(r);
        cuddRef(r);
        Cudd_RecursiveDeref(manager, t);
        Cudd_RecursiveDeref(manager, e);
        cuddDeref(r);
    } else if (t == e) {
        r = t;
        cuddDeref(t);
        cuddDeref(e);
    } else {
        if (Cudd_IsComplement(t)) {
            r = cuddUniqueInter(manager,(int)index,Cudd_Not(t),Cudd_Not(e));
            if (r == NULL) {
                Cudd_RecursiveDeref(manager, t);
                Cudd_RecursiveDeref(manager, e);
                return(NULL);
            }
            r = Cudd_Not(r);
        } else {
            r = cuddUniqueInter(manager,(int)index,t,e);
            if (r == NULL) {
                Cudd_RecursiveDeref(manager, t);
                Cudd_RecursiveDeref(manager, e);
                return(NULL);
            }
        }
        cuddDeref(e);
        cuddDeref(t);
    }
    if (F->ref != 1 || G->ref != 1)
        cuddCacheInsert(manager, cacheTag, f, g, cube, r);
    return (r);

} /* end of cuddBddClipAndAbsRecur */


ABC_NAMESPACE_IMPL_END