/**
  @file

  @ingroup cudd

  @brief Combined AND and existential abstraction for BDDs

  @author Fabio Somenzi

  @copyright@parblock
  Copyright (c) 1995-2015, 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.
  @endparblock

*/

#include "util.h"
#include "cuddInt.h"


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/** \cond */

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/** \endcond */


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/* Definition of exported functions                                          */
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/**
  @brief Takes the AND of two BDDs and simultaneously abstracts the
  variables in cube.

  @details The variables are existentially abstracted.
  Cudd_bddAndAbstract implements the semiring matrix multiplication
  algorithm for the boolean semiring.

  @return a pointer to the result is successful; NULL otherwise.

  @sideeffect None

  @see Cudd_addMatrixMultiply Cudd_addTriangle Cudd_bddAnd

*/
DdNode *
Cudd_bddAndAbstract(
  DdManager * manager,
  DdNode * f,
  DdNode * g,
  DdNode * cube)
{
    DdNode *res;

    do {
	manager->reordered = 0;
	res = cuddBddAndAbstractRecur(manager, f, g, cube);
    } while (manager->reordered == 1);
    if (manager->errorCode == CUDD_TIMEOUT_EXPIRED && manager->timeoutHandler) {
        manager->timeoutHandler(manager, manager->tohArg);
    }
    return(res);

} /* end of Cudd_bddAndAbstract */


/**
  @brief Takes the AND of two BDDs and simultaneously abstracts
  variables unless too many nodes are needed.

  @details The variables in cube are existentially abstracted.

  @return a pointer to the result is successful; NULL otherwise.
  In particular, if the number of new nodes created exceeds
  <code>limit</code>, this function returns NULL.

  @sideeffect None

  @see Cudd_bddAndAbstract

*/
DdNode *
Cudd_bddAndAbstractLimit(
  DdManager * manager,
  DdNode * f,
  DdNode * g,
  DdNode * cube,
  unsigned int limit)
{
    DdNode *res;
    unsigned int saveLimit = manager->maxLive;

    manager->maxLive = (manager->keys - manager->dead) +
      (manager->keysZ - manager->deadZ) + limit;
    do {
	manager->reordered = 0;
	res = cuddBddAndAbstractRecur(manager, f, g, cube);
    } while (manager->reordered == 1);
    manager->maxLive = saveLimit;
    if (manager->errorCode == CUDD_TIMEOUT_EXPIRED && manager->timeoutHandler) {
        manager->timeoutHandler(manager, manager->tohArg);
    }
    return(res);

} /* end of Cudd_bddAndAbstractLimit */


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/* Definition of internal functions                                          */
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/**
  @brief Takes the AND of two BDDs and simultaneously abstracts the
  variables in cube.

  @details The variables are existentially abstracted.

  @return a pointer to the result is successful; NULL otherwise.

  @sideeffect None

  @see Cudd_bddAndAbstract

*/
DdNode *
cuddBddAndAbstractRecur(
  DdManager * manager,
  DdNode * f,
  DdNode * g,
  DdNode * cube)
{
    DdNode *F, *ft, *fe, *G, *gt, *ge;
    DdNode *one, *zero, *r, *t, *e;
    int topf, topg, top, topcube;
    unsigned int index;

    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(cuddBddAndRecur(manager, f, g));
    }
    if (f == one || f == g) {
	return(cuddBddExistAbstractRecur(manager, g, cube));
    }
    if (g == one) {
	return(cuddBddExistAbstractRecur(manager, f, cube));
    }
    /* At this point f, g, and cube are not constant. */

    if (f > g) { /* Try to increase cache efficiency. */
	DdNode *tmp = f;
	f = g;
	g = tmp;
    }

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

    while (topcube < top) {
	cube = cuddT(cube);
	if (cube == one) {
	    return(cuddBddAndRecur(manager, f, g));
	}
	topcube = manager->perm[cube->index];
    }
    /* Now, topcube >= top. */

    /* Check cache. */
    if (F->ref != 1 || G->ref != 1) {
	r = cuddCacheLookup(manager, DD_BDD_AND_ABSTRACT_TAG, f, g, cube);
	if (r != NULL) {
	    return(r);
	}
    }

    checkWhetherToGiveUp(manager);

    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) {	/* quantify */
	DdNode *Cube = cuddT(cube);
	t = cuddBddAndAbstractRecur(manager, ft, gt, Cube);
	if (t == NULL) return(NULL);
	/* Special case: 1 OR anything = 1. Hence, no need to compute
	** the else branch if t is 1. Likewise t + t * anything == t.
	** Notice that t == fe implies that fe does not depend on the
	** variables in Cube. Likewise for t == ge.
	*/
	if (t == one || t == fe || t == ge) {
	    if (F->ref != 1 || G->ref != 1)
		cuddCacheInsert(manager, DD_BDD_AND_ABSTRACT_TAG,
				f, g, cube, t);
	    return(t);
	}
	cuddRef(t);
	/* Special case: t + !t * anything == t + anything. */
	if (t == Cudd_Not(fe)) {
	    e = cuddBddExistAbstractRecur(manager, ge, Cube);
	} else if (t == Cudd_Not(ge)) {
	    e = cuddBddExistAbstractRecur(manager, fe, Cube);
	} else {
	    e = cuddBddAndAbstractRecur(manager, fe, ge, Cube);
	}
	if (e == NULL) {
	    Cudd_IterDerefBdd(manager, t);
	    return(NULL);
	}
	if (t == e) {
	    r = t;
	    cuddDeref(t);
	} else {
	    cuddRef(e);
	    r = cuddBddAndRecur(manager, Cudd_Not(t), Cudd_Not(e));
	    if (r == NULL) {
		Cudd_IterDerefBdd(manager, t);
		Cudd_IterDerefBdd(manager, e);
		return(NULL);
	    }
	    r = Cudd_Not(r);
	    cuddRef(r);
	    Cudd_DelayedDerefBdd(manager, t);
	    Cudd_DelayedDerefBdd(manager, e);
	    cuddDeref(r);
	}
    } else {
	t = cuddBddAndAbstractRecur(manager, ft, gt, cube);
	if (t == NULL) return(NULL);
	cuddRef(t);
	e = cuddBddAndAbstractRecur(manager, fe, ge, cube);
	if (e == NULL) {
	    Cudd_IterDerefBdd(manager, t);
	    return(NULL);
	}
	if (t == e) {
	    r = t;
	    cuddDeref(t);
	} else {
	    cuddRef(e);
	    if (Cudd_IsComplement(t)) {
		r = cuddUniqueInter(manager, (int) index,
				    Cudd_Not(t), Cudd_Not(e));
		if (r == NULL) {
		    Cudd_IterDerefBdd(manager, t);
		    Cudd_IterDerefBdd(manager, e);
		    return(NULL);
		}
		r = Cudd_Not(r);
	    } else {
		r = cuddUniqueInter(manager,(int)index,t,e);
		if (r == NULL) {
		    Cudd_IterDerefBdd(manager, t);
		    Cudd_IterDerefBdd(manager, e);
		    return(NULL);
		}
	    }
	    cuddDeref(e);
	    cuddDeref(t);
	}
    }

    if (F->ref != 1 || G->ref != 1)
	cuddCacheInsert(manager, DD_BDD_AND_ABSTRACT_TAG, f, g, cube, r);
    return (r);

} /* end of cuddBddAndAbstractRecur */


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/* Definition of static functions                                            */
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