cuddCof.c File Reference

#include "misc/util/util_hack.h"
#include "cuddInt.h"

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 ABC_NAMESPACE_IMPL_START char rcsid[]	DD_UNUSED = "$Id: cuddCof.c,v 1.9 2004/08/13 18:04:47 fabio 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 123 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 193 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 230 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 162 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

ABC_NAMESPACE_IMPL_START char rcsid [] DD_UNUSED = "$Id: cuddCof.c,v 1.9 2004/08/13 18:04:47 fabio 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 [Copyright (c) 1995-2004, 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.]

Definition at line 86 of file cuddCof.c.