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364 lines
10 KiB
364 lines
10 KiB
/**
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@file
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@ingroup cudd
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@brief Combined AND and existential abstraction for BDDs
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@author Fabio Somenzi
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@copyright@parblock
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Copyright (c) 1995-2015, Regents of the University of Colorado
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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Neither the name of the University of Colorado nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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@endparblock
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*/
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#include "util.h"
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#include "cuddInt.h"
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/*---------------------------------------------------------------------------*/
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/* Constant declarations */
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/*---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------*/
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/* Stucture declarations */
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/*---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------*/
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/* Type declarations */
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/*---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------*/
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/* Variable declarations */
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/*---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------*/
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/* Macro declarations */
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/*---------------------------------------------------------------------------*/
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/** \cond */
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/*---------------------------------------------------------------------------*/
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/* Static function prototypes */
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/*---------------------------------------------------------------------------*/
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/** \endcond */
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/*---------------------------------------------------------------------------*/
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/* Definition of exported functions */
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/*---------------------------------------------------------------------------*/
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/**
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@brief Takes the AND of two BDDs and simultaneously abstracts the
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variables in cube.
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@details The variables are existentially abstracted.
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Cudd_bddAndAbstract implements the semiring matrix multiplication
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algorithm for the boolean semiring.
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@return a pointer to the result is successful; NULL otherwise.
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@sideeffect None
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@see Cudd_addMatrixMultiply Cudd_addTriangle Cudd_bddAnd
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*/
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DdNode *
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Cudd_bddAndAbstract(
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DdManager * manager,
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DdNode * f,
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DdNode * g,
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DdNode * cube)
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{
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DdNode *res;
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do {
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manager->reordered = 0;
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res = cuddBddAndAbstractRecur(manager, f, g, cube);
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} while (manager->reordered == 1);
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if (manager->errorCode == CUDD_TIMEOUT_EXPIRED && manager->timeoutHandler) {
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manager->timeoutHandler(manager, manager->tohArg);
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}
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return(res);
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} /* end of Cudd_bddAndAbstract */
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/**
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@brief Takes the AND of two BDDs and simultaneously abstracts
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variables unless too many nodes are needed.
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@details The variables in cube are existentially abstracted.
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@return a pointer to the result is successful; NULL otherwise.
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In particular, if the number of new nodes created exceeds
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<code>limit</code>, this function returns NULL.
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@sideeffect None
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@see Cudd_bddAndAbstract
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*/
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DdNode *
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Cudd_bddAndAbstractLimit(
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DdManager * manager,
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DdNode * f,
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DdNode * g,
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DdNode * cube,
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unsigned int limit)
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{
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DdNode *res;
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unsigned int saveLimit = manager->maxLive;
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manager->maxLive = (manager->keys - manager->dead) +
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(manager->keysZ - manager->deadZ) + limit;
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do {
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manager->reordered = 0;
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res = cuddBddAndAbstractRecur(manager, f, g, cube);
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} while (manager->reordered == 1);
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manager->maxLive = saveLimit;
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if (manager->errorCode == CUDD_TIMEOUT_EXPIRED && manager->timeoutHandler) {
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manager->timeoutHandler(manager, manager->tohArg);
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}
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return(res);
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} /* end of Cudd_bddAndAbstractLimit */
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/*---------------------------------------------------------------------------*/
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/* Definition of internal functions */
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/*---------------------------------------------------------------------------*/
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/**
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@brief Takes the AND of two BDDs and simultaneously abstracts the
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variables in cube.
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@details The variables are existentially abstracted.
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@return a pointer to the result is successful; NULL otherwise.
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@sideeffect None
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@see Cudd_bddAndAbstract
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*/
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DdNode *
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cuddBddAndAbstractRecur(
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DdManager * manager,
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DdNode * f,
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DdNode * g,
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DdNode * cube)
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{
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DdNode *F, *ft, *fe, *G, *gt, *ge;
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DdNode *one, *zero, *r, *t, *e;
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int topf, topg, top, topcube;
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unsigned int index;
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statLine(manager);
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one = DD_ONE(manager);
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zero = Cudd_Not(one);
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/* Terminal cases. */
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if (f == zero || g == zero || f == Cudd_Not(g)) return(zero);
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if (f == one && g == one) return(one);
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if (cube == one) {
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return(cuddBddAndRecur(manager, f, g));
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}
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if (f == one || f == g) {
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return(cuddBddExistAbstractRecur(manager, g, cube));
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}
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if (g == one) {
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return(cuddBddExistAbstractRecur(manager, f, cube));
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}
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/* At this point f, g, and cube are not constant. */
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if (f > g) { /* Try to increase cache efficiency. */
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DdNode *tmp = f;
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f = g;
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g = tmp;
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}
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/* Here we can skip the use of cuddI, because the operands are known
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** to be non-constant.
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*/
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F = Cudd_Regular(f);
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G = Cudd_Regular(g);
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topf = manager->perm[F->index];
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topg = manager->perm[G->index];
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top = ddMin(topf, topg);
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topcube = manager->perm[cube->index];
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while (topcube < top) {
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cube = cuddT(cube);
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if (cube == one) {
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return(cuddBddAndRecur(manager, f, g));
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}
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topcube = manager->perm[cube->index];
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}
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/* Now, topcube >= top. */
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/* Check cache. */
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if (F->ref != 1 || G->ref != 1) {
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r = cuddCacheLookup(manager, DD_BDD_AND_ABSTRACT_TAG, f, g, cube);
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if (r != NULL) {
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return(r);
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}
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}
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checkWhetherToGiveUp(manager);
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if (topf == top) {
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index = F->index;
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ft = cuddT(F);
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fe = cuddE(F);
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if (Cudd_IsComplement(f)) {
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ft = Cudd_Not(ft);
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fe = Cudd_Not(fe);
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}
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} else {
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index = G->index;
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ft = fe = f;
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}
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if (topg == top) {
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gt = cuddT(G);
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ge = cuddE(G);
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if (Cudd_IsComplement(g)) {
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gt = Cudd_Not(gt);
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ge = Cudd_Not(ge);
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}
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} else {
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gt = ge = g;
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}
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if (topcube == top) { /* quantify */
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DdNode *Cube = cuddT(cube);
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t = cuddBddAndAbstractRecur(manager, ft, gt, Cube);
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if (t == NULL) return(NULL);
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/* Special case: 1 OR anything = 1. Hence, no need to compute
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** the else branch if t is 1. Likewise t + t * anything == t.
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** Notice that t == fe implies that fe does not depend on the
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** variables in Cube. Likewise for t == ge.
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*/
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if (t == one || t == fe || t == ge) {
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if (F->ref != 1 || G->ref != 1)
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cuddCacheInsert(manager, DD_BDD_AND_ABSTRACT_TAG,
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f, g, cube, t);
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return(t);
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}
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cuddRef(t);
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/* Special case: t + !t * anything == t + anything. */
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if (t == Cudd_Not(fe)) {
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e = cuddBddExistAbstractRecur(manager, ge, Cube);
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} else if (t == Cudd_Not(ge)) {
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e = cuddBddExistAbstractRecur(manager, fe, Cube);
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} else {
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e = cuddBddAndAbstractRecur(manager, fe, ge, Cube);
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}
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if (e == NULL) {
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Cudd_IterDerefBdd(manager, t);
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return(NULL);
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}
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if (t == e) {
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r = t;
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cuddDeref(t);
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} else {
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cuddRef(e);
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r = cuddBddAndRecur(manager, Cudd_Not(t), Cudd_Not(e));
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if (r == NULL) {
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Cudd_IterDerefBdd(manager, t);
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Cudd_IterDerefBdd(manager, e);
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return(NULL);
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}
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r = Cudd_Not(r);
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cuddRef(r);
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Cudd_DelayedDerefBdd(manager, t);
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Cudd_DelayedDerefBdd(manager, e);
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cuddDeref(r);
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}
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} else {
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t = cuddBddAndAbstractRecur(manager, ft, gt, cube);
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if (t == NULL) return(NULL);
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cuddRef(t);
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e = cuddBddAndAbstractRecur(manager, fe, ge, cube);
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if (e == NULL) {
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Cudd_IterDerefBdd(manager, t);
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return(NULL);
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}
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if (t == e) {
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r = t;
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cuddDeref(t);
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} else {
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cuddRef(e);
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if (Cudd_IsComplement(t)) {
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r = cuddUniqueInter(manager, (int) index,
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Cudd_Not(t), Cudd_Not(e));
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if (r == NULL) {
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Cudd_IterDerefBdd(manager, t);
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Cudd_IterDerefBdd(manager, e);
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return(NULL);
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}
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r = Cudd_Not(r);
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} else {
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r = cuddUniqueInter(manager,(int)index,t,e);
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if (r == NULL) {
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Cudd_IterDerefBdd(manager, t);
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Cudd_IterDerefBdd(manager, e);
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return(NULL);
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}
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}
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cuddDeref(e);
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cuddDeref(t);
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}
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}
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if (F->ref != 1 || G->ref != 1)
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cuddCacheInsert(manager, DD_BDD_AND_ABSTRACT_TAG, f, g, cube, r);
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return (r);
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} /* end of cuddBddAndAbstractRecur */
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/*---------------------------------------------------------------------------*/
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/* Definition of static functions */
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/*---------------------------------------------------------------------------*/
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