src/bdd/cudd/cuddCof.c File Reference

#include "util_hack.h"
#include "cuddInt.h"

Include dependency graph for cuddCof.c:

Go to the source code of this file.

Functions
DdNode *	Cudd_Cofactor (DdManager *dd, DdNode *f, DdNode *g)
void	cuddGetBranches (DdNode *g, DdNode **g1, DdNode **g0)
int	cuddCheckCube (DdManager *dd, DdNode *g)
DdNode *	cuddCofactorRecur (DdManager *dd, DdNode *f, DdNode *g)
Variables
static char rcsid[]	DD_UNUSED = "$Id: cuddCof.c,v 1.1.1.1 2003/02/24 22:23:51 wjiang Exp $"

---

Function Documentation

DdNode* Cudd_Cofactor	(	DdManager *	dd,
		DdNode *	f,
		DdNode *	g
	)

AutomaticStart AutomaticEnd Function********************************************************************

Synopsis [Computes the cofactor of f with respect to g.]

Description [Computes the cofactor of f with respect to g; g must be the BDD or the ADD of a cube. Returns a pointer to the cofactor if successful; NULL otherwise.]

SideEffects [None]

SeeAlso [Cudd_bddConstrain Cudd_bddRestrict]

Definition at line 92 of file cuddCof.c.

{
    DdNode *res,*zero;

    zero = Cudd_Not(DD_ONE(dd));
    if (g == zero || g == DD_ZERO(dd)) {
        (void) fprintf(dd->err,"Cudd_Cofactor: Invalid restriction 1\n");
        dd->errorCode = CUDD_INVALID_ARG;
        return(NULL);
    }
    do {
        dd->reordered = 0;
        res = cuddCofactorRecur(dd,f,g);
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_Cofactor */

int cuddCheckCube	(	DdManager *	dd,
		DdNode *	g
	)

Function********************************************************************

Synopsis [Checks whether g is the BDD of a cube.]

Description [Checks whether g is the BDD of a cube. Returns 1 in case of success; 0 otherwise. The constant 1 is a valid cube, but all other constant functions cause cuddCheckCube to return 0.]

SideEffects [None]

SeeAlso []

Definition at line 162 of file cuddCof.c.

{
    DdNode *g1,*g0,*one,*zero;
    
    one = DD_ONE(dd);
    if (g == one) return(1);
    if (Cudd_IsConstant(g)) return(0);

    zero = Cudd_Not(one);
    cuddGetBranches(g,&g1,&g0);

    if (g0 == zero) {
        return(cuddCheckCube(dd, g1));
    }
    if (g1 == zero) {
        return(cuddCheckCube(dd, g0));
    }
    return(0);

} /* end of cuddCheckCube */

DdNode* cuddCofactorRecur	(	DdManager *	dd,
		DdNode *	f,
		DdNode *	g
	)

Function********************************************************************

Synopsis [Performs the recursive step of Cudd_Cofactor.]

Description [Performs the recursive step of Cudd_Cofactor. Returns a pointer to the cofactor if successful; NULL otherwise.]

SideEffects [None]

SeeAlso [Cudd_Cofactor]

Definition at line 199 of file cuddCof.c.

{
    DdNode *one,*zero,*F,*G,*g1,*g0,*f1,*f0,*t,*e,*r;
    unsigned int topf,topg;
    int comple;

    statLine(dd);
    F = Cudd_Regular(f);
    if (cuddIsConstant(F)) return(f);

    one = DD_ONE(dd);

    /* The invariant g != 0 is true on entry to this procedure and is
    ** recursively maintained by it. Therefore it suffices to test g
    ** against one to make sure it is not constant.
    */
    if (g == one) return(f);
    /* From now on, f and g are known not to be constants. */

    comple = f != F;
    r = cuddCacheLookup2(dd,Cudd_Cofactor,F,g);
    if (r != NULL) {
        return(Cudd_NotCond(r,comple));
    }

    topf = dd->perm[F->index];
    G = Cudd_Regular(g);
    topg = dd->perm[G->index];

    /* We take the cofactors of F because we are going to rely on
    ** the fact that the cofactors of the complement are the complements
    ** of the cofactors to better utilize the cache. Variable comple
    ** remembers whether we have to complement the result or not.
    */
    if (topf <= topg) {
        f1 = cuddT(F); f0 = cuddE(F);
    } else {
        f1 = f0 = F;
    }
    if (topg <= topf) {
        g1 = cuddT(G); g0 = cuddE(G);
        if (g != G) { g1 = Cudd_Not(g1); g0 = Cudd_Not(g0); }
    } else {
        g1 = g0 = g;
    }

    zero = Cudd_Not(one);
    if (topf >= topg) {
        if (g0 == zero || g0 == DD_ZERO(dd)) {
            r = cuddCofactorRecur(dd, f1, g1);
        } else if (g1 == zero || g1 == DD_ZERO(dd)) {
            r = cuddCofactorRecur(dd, f0, g0);
        } else {
            (void) fprintf(dd->out,
                           "Cudd_Cofactor: Invalid restriction 2\n");
            dd->errorCode = CUDD_INVALID_ARG;
            return(NULL);
        }
        if (r == NULL) return(NULL);
    } else /* if (topf < topg) */ {
        t = cuddCofactorRecur(dd, f1, g);
        if (t == NULL) return(NULL);
        cuddRef(t);
        e = cuddCofactorRecur(dd, f0, g);
        if (e == NULL) {
            Cudd_RecursiveDeref(dd, t);
            return(NULL);
        }
        cuddRef(e);

        if (t == e) {
            r = t;
        } else if (Cudd_IsComplement(t)) {
            r = cuddUniqueInter(dd,(int)F->index,Cudd_Not(t),Cudd_Not(e));
            if (r != NULL)
                r = Cudd_Not(r);
        } else {
            r = cuddUniqueInter(dd,(int)F->index,t,e);
        }
        if (r == NULL) {
            Cudd_RecursiveDeref(dd ,e);
            Cudd_RecursiveDeref(dd ,t);
            return(NULL);
        }
        cuddDeref(t);
        cuddDeref(e);
    }

    cuddCacheInsert2(dd,Cudd_Cofactor,F,g,r);

    return(Cudd_NotCond(r,comple));

} /* end of cuddCofactorRecur */

void cuddGetBranches	(	DdNode *	g,
		DdNode **	g1,
		DdNode **	g0
	)

Function********************************************************************

Synopsis [Computes the children of g.]

Description []

SideEffects [None]

SeeAlso []

Definition at line 131 of file cuddCof.c.

{
    DdNode      *G = Cudd_Regular(g);

    *g1 = cuddT(G);
    *g0 = cuddE(G);
    if (Cudd_IsComplement(g)) {
        *g1 = Cudd_Not(*g1);
        *g0 = Cudd_Not(*g0);
    }

} /* end of cuddGetBranches */

---

Variable Documentation

char rcsid [] DD_UNUSED = "$Id: cuddCof.c,v 1.1.1.1 2003/02/24 22:23:51 wjiang Exp $" [static]

CFile***********************************************************************

FileName [cuddCof.c]

PackageName [cudd]

Synopsis [Cofactoring functions.]

Description [External procedures included in this module:

• Cudd_Cofactor()

Internal procedures included in this module:

• cuddGetBranches()
• cuddCheckCube()
• cuddCofactorRecur()

]

SeeAlso []

Author [Fabio Somenzi]

Copyright [ This file was created at the University of Colorado at Boulder. The University of Colorado at Boulder makes no warranty about the suitability of this software for any purpose. It is presented on an AS IS basis.]

Definition at line 55 of file cuddCof.c.