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327 lines
9.5 KiB
327 lines
9.5 KiB
/**CFile***********************************************************************
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FileName [cuddCof.c]
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PackageName [cudd]
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Synopsis [Cofactoring functions.]
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Description [External procedures included in this module:
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<ul>
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<li> Cudd_Cofactor()
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<li> Cudd_CheckCube()
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</ul>
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Internal procedures included in this module:
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<ul>
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<li> cuddGetBranches()
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<li> cuddCofactorRecur()
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</ul>
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]
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SeeAlso []
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Author [Fabio Somenzi]
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Copyright [Copyright (c) 1995-2012, 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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******************************************************************************/
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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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#ifndef lint
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static char rcsid[] DD_UNUSED = "$Id: cuddCof.c,v 1.11 2012/02/05 01:07:18 fabio Exp $";
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#endif
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/*---------------------------------------------------------------------------*/
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/* Macro declarations */
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/*---------------------------------------------------------------------------*/
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/**AutomaticStart*************************************************************/
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/*---------------------------------------------------------------------------*/
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/* Static function prototypes */
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/*---------------------------------------------------------------------------*/
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/**AutomaticEnd***************************************************************/
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/*---------------------------------------------------------------------------*/
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/* Definition of exported functions */
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/*---------------------------------------------------------------------------*/
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/**Function********************************************************************
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Synopsis [Computes the cofactor of f with respect to g.]
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Description [Computes the cofactor of f with respect to g; g must be
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the BDD or the ADD of a cube. Returns a pointer to the cofactor if
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successful; NULL otherwise.]
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SideEffects [None]
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SeeAlso [Cudd_bddConstrain Cudd_bddRestrict]
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******************************************************************************/
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DdNode *
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Cudd_Cofactor(
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DdManager * dd,
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DdNode * f,
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DdNode * g)
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{
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DdNode *res,*zero;
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zero = Cudd_Not(DD_ONE(dd));
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if (g == zero || g == DD_ZERO(dd)) {
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(void) fprintf(dd->err,"Cudd_Cofactor: Invalid restriction 1\n");
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dd->errorCode = CUDD_INVALID_ARG;
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return(NULL);
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}
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do {
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dd->reordered = 0;
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res = cuddCofactorRecur(dd,f,g);
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} while (dd->reordered == 1);
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return(res);
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} /* end of Cudd_Cofactor */
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/**Function********************************************************************
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Synopsis [Checks whether g is the BDD of a cube.]
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Description [Checks whether g is the BDD of a cube. Returns 1 in case
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of success; 0 otherwise. The constant 1 is a valid cube, but all other
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constant functions cause cuddCheckCube to return 0.]
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SideEffects [None]
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SeeAlso []
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******************************************************************************/
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int
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Cudd_CheckCube(
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DdManager * dd,
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DdNode * g)
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{
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DdNode *g1,*g0,*one,*zero;
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one = DD_ONE(dd);
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if (g == one) return(1);
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if (Cudd_IsConstant(g)) return(0);
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zero = Cudd_Not(one);
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cuddGetBranches(g,&g1,&g0);
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if (g0 == zero) {
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return(Cudd_CheckCube(dd, g1));
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}
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if (g1 == zero) {
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return(Cudd_CheckCube(dd, g0));
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}
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return(0);
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} /* end of Cudd_CheckCube */
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/*---------------------------------------------------------------------------*/
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/* Definition of internal functions */
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/*---------------------------------------------------------------------------*/
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/**Function********************************************************************
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Synopsis [Computes the children of g.]
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Description []
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SideEffects [None]
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SeeAlso []
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******************************************************************************/
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void
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cuddGetBranches(
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DdNode * g,
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DdNode ** g1,
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DdNode ** g0)
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{
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DdNode *G = Cudd_Regular(g);
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*g1 = cuddT(G);
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*g0 = cuddE(G);
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if (Cudd_IsComplement(g)) {
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*g1 = Cudd_Not(*g1);
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*g0 = Cudd_Not(*g0);
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}
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} /* end of cuddGetBranches */
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/**Function********************************************************************
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Synopsis [Performs the recursive step of Cudd_Cofactor.]
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Description [Performs the recursive step of Cudd_Cofactor. Returns a
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pointer to the cofactor if successful; NULL otherwise.]
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SideEffects [None]
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SeeAlso [Cudd_Cofactor]
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******************************************************************************/
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DdNode *
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cuddCofactorRecur(
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DdManager * dd,
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DdNode * f,
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DdNode * g)
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{
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DdNode *one,*zero,*F,*G,*g1,*g0,*f1,*f0,*t,*e,*r;
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unsigned int topf,topg;
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int comple;
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statLine(dd);
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F = Cudd_Regular(f);
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if (cuddIsConstant(F)) return(f);
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one = DD_ONE(dd);
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/* The invariant g != 0 is true on entry to this procedure and is
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** recursively maintained by it. Therefore it suffices to test g
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** against one to make sure it is not constant.
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*/
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if (g == one) return(f);
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/* From now on, f and g are known not to be constants. */
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comple = f != F;
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r = cuddCacheLookup2(dd,Cudd_Cofactor,F,g);
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if (r != NULL) {
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return(Cudd_NotCond(r,comple));
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}
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topf = dd->perm[F->index];
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G = Cudd_Regular(g);
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topg = dd->perm[G->index];
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/* We take the cofactors of F because we are going to rely on
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** the fact that the cofactors of the complement are the complements
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** of the cofactors to better utilize the cache. Variable comple
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** remembers whether we have to complement the result or not.
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*/
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if (topf <= topg) {
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f1 = cuddT(F); f0 = cuddE(F);
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} else {
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f1 = f0 = F;
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}
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if (topg <= topf) {
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g1 = cuddT(G); g0 = cuddE(G);
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if (g != G) { g1 = Cudd_Not(g1); g0 = Cudd_Not(g0); }
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} else {
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g1 = g0 = g;
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}
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zero = Cudd_Not(one);
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if (topf >= topg) {
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if (g0 == zero || g0 == DD_ZERO(dd)) {
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r = cuddCofactorRecur(dd, f1, g1);
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} else if (g1 == zero || g1 == DD_ZERO(dd)) {
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r = cuddCofactorRecur(dd, f0, g0);
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} else {
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(void) fprintf(dd->out,
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"Cudd_Cofactor: Invalid restriction 2\n");
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dd->errorCode = CUDD_INVALID_ARG;
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return(NULL);
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}
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if (r == NULL) return(NULL);
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} else /* if (topf < topg) */ {
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t = cuddCofactorRecur(dd, f1, g);
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if (t == NULL) return(NULL);
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cuddRef(t);
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e = cuddCofactorRecur(dd, f0, g);
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if (e == NULL) {
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Cudd_RecursiveDeref(dd, t);
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return(NULL);
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}
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cuddRef(e);
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if (t == e) {
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r = t;
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} else if (Cudd_IsComplement(t)) {
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r = cuddUniqueInter(dd,(int)F->index,Cudd_Not(t),Cudd_Not(e));
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if (r != NULL)
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r = Cudd_Not(r);
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} else {
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r = cuddUniqueInter(dd,(int)F->index,t,e);
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}
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if (r == NULL) {
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Cudd_RecursiveDeref(dd ,e);
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Cudd_RecursiveDeref(dd ,t);
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return(NULL);
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}
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cuddDeref(t);
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cuddDeref(e);
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}
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cuddCacheInsert2(dd,Cudd_Cofactor,F,g,r);
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return(Cudd_NotCond(r,comple));
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} /* end of cuddCofactorRecur */
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/*---------------------------------------------------------------------------*/
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/* Definition of static functions */
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/*---------------------------------------------------------------------------*/
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