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172 lines
5.4 KiB
172 lines
5.4 KiB
/**CFile***********************************************************************
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FileName [cuddAddInv.c]
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PackageName [cudd]
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Synopsis [Function to compute the scalar inverse of an ADD.]
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Description [External procedures included in this module:
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<ul>
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<li> Cudd_addScalarInverse()
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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> cuddAddScalarInverseRecur()
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</ul>]
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Author [Fabio Somenzi]
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Copyright [This file was created at the University of Colorado at
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Boulder. The University of Colorado at Boulder makes no warranty
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about the suitability of this software for any purpose. It is
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presented on an AS IS basis.]
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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: cuddAddInv.c,v 1.7 1998/09/11 21:37:12 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 scalar inverse of an ADD.]
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Description [Computes an n ADD where the discriminants are the
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multiplicative inverses of the corresponding discriminants of the
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argument ADD. Returns a pointer to the resulting ADD in case of
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success. Returns NULL if any discriminants smaller than epsilon is
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encountered.]
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SideEffects [None]
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******************************************************************************/
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DdNode *
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Cudd_addScalarInverse(
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DdManager * dd,
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DdNode * f,
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DdNode * epsilon)
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{
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DdNode *res;
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if (!cuddIsConstant(epsilon)) {
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(void) fprintf(dd->err,"Invalid epsilon\n");
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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 = cuddAddScalarInverseRecur(dd,f,epsilon);
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} while (dd->reordered == 1);
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return(res);
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} /* end of Cudd_addScalarInverse */
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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 [Performs the recursive step of addScalarInverse.]
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Description [Returns a pointer to the resulting ADD in case of
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success. Returns NULL if any discriminants smaller than epsilon is
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encountered.]
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SideEffects [None]
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******************************************************************************/
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DdNode *
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cuddAddScalarInverseRecur(
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DdManager * dd,
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DdNode * f,
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DdNode * epsilon)
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{
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DdNode *t, *e, *res;
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CUDD_VALUE_TYPE value;
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statLine(dd);
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if (cuddIsConstant(f)) {
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if (ddAbs(cuddV(f)) < cuddV(epsilon)) return(NULL);
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value = 1.0 / cuddV(f);
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res = cuddUniqueConst(dd,value);
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return(res);
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}
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res = cuddCacheLookup2(dd,Cudd_addScalarInverse,f,epsilon);
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if (res != NULL) return(res);
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t = cuddAddScalarInverseRecur(dd,cuddT(f),epsilon);
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if (t == NULL) return(NULL);
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cuddRef(t);
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e = cuddAddScalarInverseRecur(dd,cuddE(f),epsilon);
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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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res = (t == e) ? t : cuddUniqueInter(dd,(int)f->index,t,e);
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if (res == NULL) {
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Cudd_RecursiveDeref(dd, t);
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Cudd_RecursiveDeref(dd, e);
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return(NULL);
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}
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cuddCacheInsert2(dd,Cudd_addScalarInverse,f,epsilon,res);
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return(res);
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} /* end of cuddAddScalarInverseRecur */
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/*---------------------------------------------------------------------------*/
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/* Definition of static functions */
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/*---------------------------------------------------------------------------*/
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