src/bdd/cudd/cuddBddIte.c File Reference

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

Include dependency graph for cuddBddIte.c:

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Functions
static void bddVarToConst	ARGS ((DdNode *f, DdNode **gp, DdNode **hp, DdNode *one))
static int bddVarToCanonical	ARGS ((DdManager *dd, DdNode **fp, DdNode **gp, DdNode **hp, unsigned int *topfp, unsigned int *topgp, unsigned int *tophp))
DdNode *	Cudd_bddIte (DdManager *dd, DdNode *f, DdNode *g, DdNode *h)
DdNode *	Cudd_bddIteConstant (DdManager *dd, DdNode *f, DdNode *g, DdNode *h)
DdNode *	Cudd_bddIntersect (DdManager *dd, DdNode *f, DdNode *g)
DdNode *	Cudd_bddAnd (DdManager *dd, DdNode *f, DdNode *g)
DdNode *	Cudd_bddOr (DdManager *dd, DdNode *f, DdNode *g)
DdNode *	Cudd_bddNand (DdManager *dd, DdNode *f, DdNode *g)
DdNode *	Cudd_bddNor (DdManager *dd, DdNode *f, DdNode *g)
DdNode *	Cudd_bddXor (DdManager *dd, DdNode *f, DdNode *g)
DdNode *	Cudd_bddXnor (DdManager *dd, DdNode *f, DdNode *g)
int	Cudd_bddLeq (DdManager *dd, DdNode *f, DdNode *g)
DdNode *	cuddBddIteRecur (DdManager *dd, DdNode *f, DdNode *g, DdNode *h)
DdNode *	cuddBddIntersectRecur (DdManager *dd, DdNode *f, DdNode *g)
DdNode *	cuddBddAndRecur (DdManager *manager, DdNode *f, DdNode *g)
DdNode *	cuddBddXorRecur (DdManager *manager, DdNode *f, DdNode *g)
static void	bddVarToConst (DdNode *f, DdNode **gp, DdNode **hp, DdNode *one)
static int	bddVarToCanonical (DdManager *dd, DdNode **fp, DdNode **gp, DdNode **hp, unsigned int *topfp, unsigned int *topgp, unsigned int *tophp)
static int	bddVarToCanonicalSimple (DdManager *dd, DdNode **fp, DdNode **gp, DdNode **hp, unsigned int *topfp, unsigned int *topgp, unsigned int *tophp)
Variables
static char rcsid[]	DD_UNUSED = "$Id: cuddBddIte.c,v 1.1.1.1 2003/02/24 22:23:51 wjiang Exp $"

---

Function Documentation

static int bddVarToCanonicalSimple ARGS

(

(DdManager *dd, DdNode **fp, DdNode **gp, DdNode **hp, unsigned int *topfp, unsigned int *topgp, unsigned int *tophp)

)

[static]

static void bddVarToConst ARGS

(

(DdNode *f, DdNode **gp, DdNode **hp, DdNode *one)

)

[static]

AutomaticStart

static int bddVarToCanonical	(	DdManager *	dd,
		DdNode **	fp,
		DdNode **	gp,
		DdNode **	hp,
		unsigned int *	topfp,
		unsigned int *	topgp,
		unsigned int *	tophp
	)			[static]

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

Synopsis [Picks unique member from equiv expressions.]

Description [Reduces 2 variable expressions to canonical form.]

SideEffects [None]

SeeAlso [bddVarToConst bddVarToCanonicalSimple]

Definition at line 1103 of file cuddBddIte.c.

{
    register DdNode             *F, *G, *H, *r, *f, *g, *h;
    register unsigned int       topf, topg, toph;
    DdNode                      *one = dd->one;
    int                         comple, change;

    f = *fp;
    g = *gp;
    h = *hp;
    F = Cudd_Regular(f);
    G = Cudd_Regular(g);
    H = Cudd_Regular(h);
    topf = cuddI(dd,F->index);
    topg = cuddI(dd,G->index);
    toph = cuddI(dd,H->index);

    change = 0;

    if (G == one) {                     /* ITE(F,c,H) */
        if ((topf > toph) || (topf == toph && f > h)) {
            r = h;
            h = f;
            f = r;                      /* ITE(F,1,H) = ITE(H,1,F) */
            if (g != one) {     /* g == zero */
                f = Cudd_Not(f);                /* ITE(F,0,H) = ITE(!H,0,!F) */
                h = Cudd_Not(h);
            }
            change = 1;
        }
    } else if (H == one) {              /* ITE(F,G,c) */
        if ((topf > topg) || (topf == topg && f > g)) {
            r = g;
            g = f;
            f = r;                      /* ITE(F,G,0) = ITE(G,F,0) */
            if (h == one) {
                f = Cudd_Not(f);                /* ITE(F,G,1) = ITE(!G,!F,1) */
                g = Cudd_Not(g);
            }
            change = 1;
        }
    } else if (g == Cudd_Not(h)) {      /* ITE(F,G,!G) = ITE(G,F,!F) */
        if ((topf > topg) || (topf == topg && f > g)) {
            r = f;
            f = g;
            g = r;
            h = Cudd_Not(r);
            change = 1;
        }
    }
    /* adjust pointers so that the first 2 arguments to ITE are regular */
    if (Cudd_IsComplement(f) != 0) {    /* ITE(!F,G,H) = ITE(F,H,G) */
        f = Cudd_Not(f);
        r = g;
        g = h;
        h = r;
        change = 1;
    }
    comple = 0;
    if (Cudd_IsComplement(g) != 0) {    /* ITE(F,!G,H) = !ITE(F,G,!H) */
        g = Cudd_Not(g);
        h = Cudd_Not(h);
        change = 1;
        comple = 1;
    }
    if (change != 0) {
        *fp = f;
        *gp = g;
        *hp = h;
    }
    *topfp = cuddI(dd,f->index);
    *topgp = cuddI(dd,g->index);
    *tophp = cuddI(dd,Cudd_Regular(h)->index);

    return(comple);

} /* end of bddVarToCanonical */

static int bddVarToCanonicalSimple	(	DdManager *	dd,
		DdNode **	fp,
		DdNode **	gp,
		DdNode **	hp,
		unsigned int *	topfp,
		unsigned int *	topgp,
		unsigned int *	tophp
	)			[static]

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

Synopsis [Picks unique member from equiv expressions.]

Description [Makes sure the first two pointers are regular. This mat require the complementation of the result, which is signaled by returning 1 instead of 0. This function is simpler than the general case because it assumes that no two arguments are the same or complementary, and no argument is constant.]

SideEffects [None]

SeeAlso [bddVarToConst bddVarToCanonical]

Definition at line 1205 of file cuddBddIte.c.

{
    register DdNode             *r, *f, *g, *h;
    int                         comple, change;

    f = *fp;
    g = *gp;
    h = *hp;

    change = 0;

    /* adjust pointers so that the first 2 arguments to ITE are regular */
    if (Cudd_IsComplement(f)) { /* ITE(!F,G,H) = ITE(F,H,G) */
        f = Cudd_Not(f);
        r = g;
        g = h;
        h = r;
        change = 1;
    }
    comple = 0;
    if (Cudd_IsComplement(g)) { /* ITE(F,!G,H) = !ITE(F,G,!H) */
        g = Cudd_Not(g);
        h = Cudd_Not(h);
        change = 1;
        comple = 1;
    }
    if (change) {
        *fp = f;
        *gp = g;
        *hp = h;
    }

    /* Here we can skip the use of cuddI, because the operands are known
    ** to be non-constant.
    */
    *topfp = dd->perm[f->index];
    *topgp = dd->perm[g->index];
    *tophp = dd->perm[Cudd_Regular(h)->index];

    return(comple);

} /* end of bddVarToCanonicalSimple */

static void bddVarToConst	(	DdNode *	f,
		DdNode **	gp,
		DdNode **	hp,
		DdNode *	one
	)			[static]

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

Synopsis [Replaces variables with constants if possible.]

Description [This function performs part of the transformation to standard form by replacing variables with constants if possible.]

SideEffects [None]

SeeAlso [bddVarToCanonical bddVarToCanonicalSimple]

Definition at line 1068 of file cuddBddIte.c.

{
    DdNode *g = *gp;
    DdNode *h = *hp;

    if (f == g) {    /* ITE(F,F,H) = ITE(F,1,H) = F + H */
        *gp = one;
    } else if (f == Cudd_Not(g)) {    /* ITE(F,!F,H) = ITE(F,0,H) = !F * H */
        *gp = Cudd_Not(one);
    }
    if (f == h) {    /* ITE(F,G,F) = ITE(F,G,0) = F * G */
        *hp = Cudd_Not(one);
    } else if (f == Cudd_Not(h)) {    /* ITE(F,G,!F) = ITE(F,G,1) = !F + G */
        *hp = one;
    }

} /* end of bddVarToConst */

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

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

Synopsis [Computes the conjunction of two BDDs f and g.]

Description [Computes the conjunction of two BDDs f and g. Returns a pointer to the resulting BDD if successful; NULL if the intermediate result blows up.]

SideEffects [None]

SeeAlso [Cudd_bddIte Cudd_addApply Cudd_bddAndAbstract Cudd_bddIntersect Cudd_bddOr Cudd_bddNand Cudd_bddNor Cudd_bddXor Cudd_bddXnor]

Definition at line 282 of file cuddBddIte.c.

{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddAndRecur(dd,f,g);
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_bddAnd */

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

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

Synopsis [Returns a function included in the intersection of f and g.]

Description [Computes a function included in the intersection of f and g. (That is, a witness that the intersection is not empty.) Cudd_bddIntersect tries to build as few new nodes as possible. If the only result of interest is whether f and g intersect, Cudd_bddLeq should be used instead.]

SideEffects [None]

SeeAlso [Cudd_bddLeq Cudd_bddIteConstant]

Definition at line 250 of file cuddBddIte.c.

{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddIntersectRecur(dd,f,g);
    } while (dd->reordered == 1);

    return(res);

} /* end of Cudd_bddIntersect */

DdNode* Cudd_bddIte	(	DdManager *	dd,
		DdNode *	f,
		DdNode *	g,
		DdNode *	h
	)

AutomaticEnd Function********************************************************************

Synopsis [Implements ITE(f,g,h).]

Description [Implements ITE(f,g,h). Returns a pointer to the resulting BDD if successful; NULL if the intermediate result blows up.]

SideEffects [None]

SeeAlso [Cudd_addIte Cudd_bddIteConstant Cudd_bddIntersect]

Definition at line 111 of file cuddBddIte.c.

{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddIteRecur(dd,f,g,h);
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_bddIte */

DdNode* Cudd_bddIteConstant	(	DdManager *	dd,
		DdNode *	f,
		DdNode *	g,
		DdNode *	h
	)

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

Synopsis [Implements ITEconstant(f,g,h).]

Description [Implements ITEconstant(f,g,h). Returns a pointer to the resulting BDD (which may or may not be constant) or DD_NON_CONSTANT. No new nodes are created.]

SideEffects [None]

SeeAlso [Cudd_bddIte Cudd_bddIntersect Cudd_bddLeq Cudd_addIteConstant]

Definition at line 142 of file cuddBddIte.c.

{
    DdNode       *r, *Fv, *Fnv, *Gv, *Gnv, *H, *Hv, *Hnv, *t, *e;
    DdNode       *one = DD_ONE(dd);
    DdNode       *zero = Cudd_Not(one);
    int          comple;
    unsigned int topf, topg, toph, v;

    statLine(dd);
    /* Trivial cases. */
    if (f == one)                       /* ITE(1,G,H) => G */
        return(g);
    
    if (f == zero)                      /* ITE(0,G,H) => H */
        return(h);
    
    /* f now not a constant. */
    bddVarToConst(f, &g, &h, one);      /* possibly convert g or h */
                                        /* to constants */

    if (g == h)                         /* ITE(F,G,G) => G */
        return(g);

    if (Cudd_IsConstant(g) && Cudd_IsConstant(h)) 
        return(DD_NON_CONSTANT);        /* ITE(F,1,0) or ITE(F,0,1) */
                                        /* => DD_NON_CONSTANT */
    
    if (g == Cudd_Not(h))
        return(DD_NON_CONSTANT);        /* ITE(F,G,G') => DD_NON_CONSTANT */
                                        /* if F != G and F != G' */
    
    comple = bddVarToCanonical(dd, &f, &g, &h, &topf, &topg, &toph);

    /* Cache lookup. */
    r = cuddConstantLookup(dd, DD_BDD_ITE_CONSTANT_TAG, f, g, h);
    if (r != NULL) {
        return(Cudd_NotCond(r,comple && r != DD_NON_CONSTANT));
    }

    v = ddMin(topg, toph);

    /* ITE(F,G,H) = (v,G,H) (non constant) if F = (v,1,0), v < top(G,H). */
    if (topf < v && cuddT(f) == one && cuddE(f) == zero) {
        return(DD_NON_CONSTANT);
    }

    /* Compute cofactors. */
    if (topf <= v) {
        v = ddMin(topf, v);             /* v = top_var(F,G,H) */
        Fv = cuddT(f); Fnv = cuddE(f);
    } else {
        Fv = Fnv = f;
    }

    if (topg == v) {
        Gv = cuddT(g); Gnv = cuddE(g);
    } else {
        Gv = Gnv = g;
    }

    if (toph == v) {
        H = Cudd_Regular(h);
        Hv = cuddT(H); Hnv = cuddE(H);
        if (Cudd_IsComplement(h)) {
            Hv = Cudd_Not(Hv);
            Hnv = Cudd_Not(Hnv);
        }
    } else {
        Hv = Hnv = h;
    }

    /* Recursion. */
    t = Cudd_bddIteConstant(dd, Fv, Gv, Hv);
    if (t == DD_NON_CONSTANT || !Cudd_IsConstant(t)) {
        cuddCacheInsert(dd, DD_BDD_ITE_CONSTANT_TAG, f, g, h, DD_NON_CONSTANT);
        return(DD_NON_CONSTANT);
    }
    e = Cudd_bddIteConstant(dd, Fnv, Gnv, Hnv);
    if (e == DD_NON_CONSTANT || !Cudd_IsConstant(e) || t != e) {
        cuddCacheInsert(dd, DD_BDD_ITE_CONSTANT_TAG, f, g, h, DD_NON_CONSTANT);
        return(DD_NON_CONSTANT);
    }
    cuddCacheInsert(dd, DD_BDD_ITE_CONSTANT_TAG, f, g, h, t);
    return(Cudd_NotCond(t,comple));

} /* end of Cudd_bddIteConstant */

int Cudd_bddLeq	(	DdManager *	dd,
		DdNode *	f,
		DdNode *	g
	)

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

Synopsis [Determines whether f is less than or equal to g.]

Description [Returns 1 if f is less than or equal to g; 0 otherwise. No new nodes are created.]

SideEffects [None]

SeeAlso [Cudd_bddIteConstant Cudd_addEvalConst]

Definition at line 468 of file cuddBddIte.c.

{
    DdNode *one, *zero, *tmp, *F, *fv, *fvn, *gv, *gvn;
    unsigned int topf, topg, res;

    statLine(dd);
    /* Terminal cases and normalization. */
    if (f == g) return(1);

    if (Cudd_IsComplement(g)) {
        /* Special case: if f is regular and g is complemented,
        ** f(1,...,1) = 1 > 0 = g(1,...,1).
        */
        if (!Cudd_IsComplement(f)) return(0);
        /* Both are complemented: Swap and complement because
        ** f <= g <=> g' <= f' and we want the second argument to be regular.
        */
        tmp = g;
        g = Cudd_Not(f);
        f = Cudd_Not(tmp);
    } else if (Cudd_IsComplement(f) && g < f) {
        tmp = g;
        g = Cudd_Not(f);
        f = Cudd_Not(tmp);
    }

    /* Now g is regular and, if f is not regular, f < g. */
    one = DD_ONE(dd);
    if (g == one) return(1);    /* no need to test against zero */
    if (f == one) return(0);    /* since at this point g != one */
    if (Cudd_Not(f) == g) return(0); /* because neither is constant */
    zero = Cudd_Not(one);
    if (f == zero) return(1);

    /* Here neither f nor g is constant. */

    /* Check cache. */
    tmp = cuddCacheLookup2(dd,(DdNode * (*)(DdManager *, DdNode *,
                           DdNode *))Cudd_bddLeq,f,g);
    if (tmp != NULL) {
        return(tmp == one);
    }

    /* Compute cofactors. */
    F = Cudd_Regular(f);
    topf = dd->perm[F->index];
    topg = dd->perm[g->index];
    if (topf <= topg) {
        fv = cuddT(F); fvn = cuddE(F);
        if (f != F) {
            fv = Cudd_Not(fv);
            fvn = Cudd_Not(fvn);
        }
    } else {
        fv = fvn = f;
    }
    if (topg <= topf) {
        gv = cuddT(g); gvn = cuddE(g);
    } else {
        gv = gvn = g;
    }

    /* Recursive calls. Since we want to maximize the probability of
    ** the special case f(1,...,1) > g(1,...,1), we consider the negative
    ** cofactors first. Indeed, the complementation parity of the positive
    ** cofactors is the same as the one of the parent functions.
    */
    res = Cudd_bddLeq(dd,fvn,gvn) && Cudd_bddLeq(dd,fv,gv);

    /* Store result in cache and return. */
    cuddCacheInsert2(dd,(DdNode * (*)(DdManager *, DdNode *, DdNode *))Cudd_bddLeq,f,g,(res ? one : zero));
    return(res);

} /* end of Cudd_bddLeq */

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

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

Synopsis [Computes the NAND of two BDDs f and g.]

Description [Computes the NAND of two BDDs f and g. Returns a pointer to the resulting BDD if successful; NULL if the intermediate result blows up.]

SideEffects [None]

SeeAlso [Cudd_bddIte Cudd_addApply Cudd_bddAnd Cudd_bddOr Cudd_bddNor Cudd_bddXor Cudd_bddXnor]

Definition at line 345 of file cuddBddIte.c.

{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddAndRecur(dd,f,g);
    } while (dd->reordered == 1);
    res = Cudd_NotCond(res,res != NULL);
    return(res);

} /* end of Cudd_bddNand */

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

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

Synopsis [Computes the NOR of two BDDs f and g.]

Description [Computes the NOR of two BDDs f and g. Returns a pointer to the resulting BDD if successful; NULL if the intermediate result blows up.]

SideEffects [None]

SeeAlso [Cudd_bddIte Cudd_addApply Cudd_bddAnd Cudd_bddOr Cudd_bddNand Cudd_bddXor Cudd_bddXnor]

Definition at line 377 of file cuddBddIte.c.

{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddAndRecur(dd,Cudd_Not(f),Cudd_Not(g));
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_bddNor */

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

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

Synopsis [Computes the disjunction of two BDDs f and g.]

Description [Computes the disjunction of two BDDs f and g. Returns a pointer to the resulting BDD if successful; NULL if the intermediate result blows up.]

SideEffects [None]

SeeAlso [Cudd_bddIte Cudd_addApply Cudd_bddAnd Cudd_bddNand Cudd_bddNor Cudd_bddXor Cudd_bddXnor]

Definition at line 313 of file cuddBddIte.c.

{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddAndRecur(dd,Cudd_Not(f),Cudd_Not(g));
    } while (dd->reordered == 1);
    res = Cudd_NotCond(res,res != NULL);
    return(res);

} /* end of Cudd_bddOr */

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

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

Synopsis [Computes the exclusive NOR of two BDDs f and g.]

Description [Computes the exclusive NOR of two BDDs f and g. Returns a pointer to the resulting BDD if successful; NULL if the intermediate result blows up.]

SideEffects [None]

SeeAlso [Cudd_bddIte Cudd_addApply Cudd_bddAnd Cudd_bddOr Cudd_bddNand Cudd_bddNor Cudd_bddXor]

Definition at line 439 of file cuddBddIte.c.

{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddXorRecur(dd,f,Cudd_Not(g));
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_bddXnor */

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

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

Synopsis [Computes the exclusive OR of two BDDs f and g.]

Description [Computes the exclusive OR of two BDDs f and g. Returns a pointer to the resulting BDD if successful; NULL if the intermediate result blows up.]

SideEffects [None]

SeeAlso [Cudd_bddIte Cudd_addApply Cudd_bddAnd Cudd_bddOr Cudd_bddNand Cudd_bddNor Cudd_bddXnor]

Definition at line 408 of file cuddBddIte.c.

{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddXorRecur(dd,f,g);
    } while (dd->reordered == 1);
    return(res);

} /* end of Cudd_bddXor */

DdNode* cuddBddAndRecur	(	DdManager *	manager,
		DdNode *	f,
		DdNode *	g
	)

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

Synopsis [Implements the recursive step of Cudd_bddAnd.]

Description [Implements the recursive step of Cudd_bddAnd by taking the conjunction of two BDDs. Returns a pointer to the result is successful; NULL otherwise.]

SideEffects [None]

SeeAlso [Cudd_bddAnd]

Definition at line 819 of file cuddBddIte.c.

{
    DdNode *F, *fv, *fnv, *G, *gv, *gnv;
    DdNode *one, *r, *t, *e;
    unsigned int topf, topg, index;

    statLine(manager);
    one = DD_ONE(manager);

    /* Terminal cases. */
    F = Cudd_Regular(f);
    G = Cudd_Regular(g);
    if (F == G) {
        if (f == g) return(f);
        else return(Cudd_Not(one));
    }
    if (F == one) {
        if (f == one) return(g);
        else return(f);
    }
    if (G == one) {
        if (g == one) return(f);
        else return(g);
    }

    /* At this point f and g are not constant. */
    if (f > g) { /* Try to increase cache efficiency. */
        DdNode *tmp = f;
        f = g;
        g = tmp;
        F = Cudd_Regular(f);
        G = Cudd_Regular(g);
    }

    /* Check cache. */
    if (F->ref != 1 || G->ref != 1) {
        r = cuddCacheLookup2(manager, Cudd_bddAnd, f, g);
        if (r != NULL) return(r);
    }

    /* Here we can skip the use of cuddI, because the operands are known
    ** to be non-constant.
    */
    topf = manager->perm[F->index];
    topg = manager->perm[G->index];

    /* Compute cofactors. */
    if (topf <= topg) {
        index = F->index;
        fv = cuddT(F);
        fnv = cuddE(F);
        if (Cudd_IsComplement(f)) {
            fv = Cudd_Not(fv);
            fnv = Cudd_Not(fnv);
        }
    } else {
        index = G->index;
        fv = fnv = f;
    }

    if (topg <= topf) {
        gv = cuddT(G);
        gnv = cuddE(G);
        if (Cudd_IsComplement(g)) {
            gv = Cudd_Not(gv);
            gnv = Cudd_Not(gnv);
        }
    } else {
        gv = gnv = g;
    }

    t = cuddBddAndRecur(manager, fv, gv);
    if (t == NULL) return(NULL);
    cuddRef(t);

    e = cuddBddAndRecur(manager, fnv, gnv);
    if (e == NULL) {
        Cudd_IterDerefBdd(manager, t);
        return(NULL);
    }
    cuddRef(e);

    if (t == e) {
        r = t;
    } else {
        if (Cudd_IsComplement(t)) {
            r = cuddUniqueInter(manager,(int)index,Cudd_Not(t),Cudd_Not(e));
            if (r == NULL) {
                Cudd_IterDerefBdd(manager, t);
                Cudd_IterDerefBdd(manager, e);
                return(NULL);
            }
            r = Cudd_Not(r);
        } else {
            r = cuddUniqueInter(manager,(int)index,t,e);
            if (r == NULL) {
                Cudd_IterDerefBdd(manager, t);
                Cudd_IterDerefBdd(manager, e);
                return(NULL);
            }
        }
    }
    cuddDeref(e);
    cuddDeref(t);
    if (F->ref != 1 || G->ref != 1)
        cuddCacheInsert2(manager, Cudd_bddAnd, f, g, r);
    return(r);

} /* end of cuddBddAndRecur */

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

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

Synopsis [Implements the recursive step of Cudd_bddIntersect.]

Description []

SideEffects [None]

SeeAlso [Cudd_bddIntersect]

Definition at line 704 of file cuddBddIte.c.

{
    DdNode *res;
    DdNode *F, *G, *t, *e;
    DdNode *fv, *fnv, *gv, *gnv;
    DdNode *one, *zero;
    unsigned int index, topf, topg;

    statLine(dd);
    one = DD_ONE(dd);
    zero = Cudd_Not(one);

    /* Terminal cases. */
    if (f == zero || g == zero || f == Cudd_Not(g)) return(zero);
    if (f == g || g == one) return(f);
    if (f == one) return(g);

    /* At this point f and g are not constant. */
    if (f > g) { DdNode *tmp = f; f = g; g = tmp; }
    res = cuddCacheLookup2(dd,Cudd_bddIntersect,f,g);
    if (res != NULL) return(res);

    /* Find splitting variable. Here we can skip the use of cuddI,
    ** because the operands are known to be non-constant.
    */
    F = Cudd_Regular(f);
    topf = dd->perm[F->index];
    G = Cudd_Regular(g);
    topg = dd->perm[G->index];

    /* Compute cofactors. */
    if (topf <= topg) {
        index = F->index;
        fv = cuddT(F);
        fnv = cuddE(F);
        if (Cudd_IsComplement(f)) {
            fv = Cudd_Not(fv);
            fnv = Cudd_Not(fnv);
        }
    } else {
        index = G->index;
        fv = fnv = f;
    }

    if (topg <= topf) {
        gv = cuddT(G);
        gnv = cuddE(G);
        if (Cudd_IsComplement(g)) {
            gv = Cudd_Not(gv);
            gnv = Cudd_Not(gnv);
        }
    } else {
        gv = gnv = g;
    }

    /* Compute partial results. */
    t = cuddBddIntersectRecur(dd,fv,gv);
    if (t == NULL) return(NULL);
    cuddRef(t);
    if (t != zero) {
        e = zero;
    } else {
        e = cuddBddIntersectRecur(dd,fnv,gnv);
        if (e == NULL) {
            Cudd_IterDerefBdd(dd, t);
            return(NULL);
        }
    }
    cuddRef(e);

    if (t == e) { /* both equal zero */
        res = t;
    } else if (Cudd_IsComplement(t)) {
        res = cuddUniqueInter(dd,(int)index,Cudd_Not(t),Cudd_Not(e));
        if (res == NULL) {
            Cudd_IterDerefBdd(dd, t);
            Cudd_IterDerefBdd(dd, e);
            return(NULL);
        }
        res = Cudd_Not(res);
    } else {
        res = cuddUniqueInter(dd,(int)index,t,e);
        if (res == NULL) {
            Cudd_IterDerefBdd(dd, t);
            Cudd_IterDerefBdd(dd, e);
            return(NULL);
        }
    }
    cuddDeref(e);
    cuddDeref(t);

    cuddCacheInsert2(dd,Cudd_bddIntersect,f,g,res);

    return(res);

} /* end of cuddBddIntersectRecur */

DdNode* cuddBddIteRecur	(	DdManager *	dd,
		DdNode *	f,
		DdNode *	g,
		DdNode *	h
	)

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

Synopsis [Implements the recursive step of Cudd_bddIte.]

Description [Implements the recursive step of Cudd_bddIte. Returns a pointer to the resulting BDD. NULL if the intermediate result blows up or if reordering occurs.]

SideEffects [None]

SeeAlso []

Definition at line 566 of file cuddBddIte.c.

{
    DdNode       *one, *zero, *res;
    DdNode       *r, *Fv, *Fnv, *Gv, *Gnv, *H, *Hv, *Hnv, *t, *e;
    unsigned int topf, topg, toph, v;
    int          index;
    int          comple;

    statLine(dd);
    /* Terminal cases. */

    /* One variable cases. */
    if (f == (one = DD_ONE(dd)))        /* ITE(1,G,H) = G */
        return(g);
    
    if (f == (zero = Cudd_Not(one)))    /* ITE(0,G,H) = H */
        return(h);
    
    /* From now on, f is known not to be a constant. */
    if (g == one || f == g) {   /* ITE(F,F,H) = ITE(F,1,H) = F + H */
        if (h == zero) {        /* ITE(F,1,0) = F */
            return(f);
        } else {
            res = cuddBddAndRecur(dd,Cudd_Not(f),Cudd_Not(h));
            return(Cudd_NotCond(res,res != NULL));
        }
    } else if (g == zero || f == Cudd_Not(g)) { /* ITE(F,!F,H) = ITE(F,0,H) = !F * H */
        if (h == one) {         /* ITE(F,0,1) = !F */
            return(Cudd_Not(f));
        } else {
            res = cuddBddAndRecur(dd,Cudd_Not(f),h);
            return(res);
        }
    }
    if (h == zero || f == h) {    /* ITE(F,G,F) = ITE(F,G,0) = F * G */
        res = cuddBddAndRecur(dd,f,g);
        return(res);
    } else if (h == one || f == Cudd_Not(h)) { /* ITE(F,G,!F) = ITE(F,G,1) = !F + G */
        res = cuddBddAndRecur(dd,f,Cudd_Not(g));
        return(Cudd_NotCond(res,res != NULL));
    }

    /* Check remaining one variable case. */
    if (g == h) {               /* ITE(F,G,G) = G */
        return(g);
    } else if (g == Cudd_Not(h)) { /* ITE(F,G,!G) = F <-> G */
        res = cuddBddXorRecur(dd,f,h);
        return(res);
    }
    
    /* From here, there are no constants. */
    comple = bddVarToCanonicalSimple(dd, &f, &g, &h, &topf, &topg, &toph);

    /* f & g are now regular pointers */

    v = ddMin(topg, toph);

    /* A shortcut: ITE(F,G,H) = (v,G,H) if F = (v,1,0), v < top(G,H). */
    if (topf < v && cuddT(f) == one && cuddE(f) == zero) {
        r = cuddUniqueInter(dd, (int) f->index, g, h);
        return(Cudd_NotCond(r,comple && r != NULL));
    }

    /* Check cache. */
    r = cuddCacheLookup(dd, DD_BDD_ITE_TAG, f, g, h);
    if (r != NULL) {
        return(Cudd_NotCond(r,comple));
    }

    /* Compute cofactors. */
    if (topf <= v) {
        v = ddMin(topf, v);     /* v = top_var(F,G,H) */
        index = f->index;
        Fv = cuddT(f); Fnv = cuddE(f);
    } else {
        Fv = Fnv = f;
    }
    if (topg == v) {
        index = g->index;
        Gv = cuddT(g); Gnv = cuddE(g);
    } else {
        Gv = Gnv = g;
    }
    if (toph == v) {
        H = Cudd_Regular(h);
        index = H->index;
        Hv = cuddT(H); Hnv = cuddE(H);
        if (Cudd_IsComplement(h)) {
            Hv = Cudd_Not(Hv);
            Hnv = Cudd_Not(Hnv);
        }
    } else {
        Hv = Hnv = h;
    }

    /* Recursive step. */
    t = cuddBddIteRecur(dd,Fv,Gv,Hv);
    if (t == NULL) return(NULL);
    cuddRef(t);

    e = cuddBddIteRecur(dd,Fnv,Gnv,Hnv);
    if (e == NULL) {
        Cudd_IterDerefBdd(dd,t);
        return(NULL);
    }
    cuddRef(e);

    r = (t == e) ? t : cuddUniqueInter(dd,index,t,e);
    if (r == NULL) {
        Cudd_IterDerefBdd(dd,t);
        Cudd_IterDerefBdd(dd,e);
        return(NULL);
    }
    cuddDeref(t);
    cuddDeref(e);

    cuddCacheInsert(dd, DD_BDD_ITE_TAG, f, g, h, r);
    return(Cudd_NotCond(r,comple));

} /* end of cuddBddIteRecur */

DdNode* cuddBddXorRecur	(	DdManager *	manager,
		DdNode *	f,
		DdNode *	g
	)

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

Synopsis [Implements the recursive step of Cudd_bddXor.]

Description [Implements the recursive step of Cudd_bddXor by taking the exclusive OR of two BDDs. Returns a pointer to the result is successful; NULL otherwise.]

SideEffects [None]

SeeAlso [Cudd_bddXor]

Definition at line 947 of file cuddBddIte.c.

{
    DdNode *fv, *fnv, *G, *gv, *gnv;
    DdNode *one, *zero, *r, *t, *e;
    unsigned int topf, topg, index;

    statLine(manager);
    one = DD_ONE(manager);
    zero = Cudd_Not(one);

    /* Terminal cases. */
    if (f == g) return(zero);
    if (f == Cudd_Not(g)) return(one);
    if (f > g) { /* Try to increase cache efficiency and simplify tests. */
        DdNode *tmp = f;
        f = g;
        g = tmp;
    }
    if (g == zero) return(f);
    if (g == one) return(Cudd_Not(f));
    if (Cudd_IsComplement(f)) {
        f = Cudd_Not(f);
        g = Cudd_Not(g);
    }
    /* Now the first argument is regular. */
    if (f == one) return(Cudd_Not(g));

    /* At this point f and g are not constant. */

    /* Check cache. */
    r = cuddCacheLookup2(manager, Cudd_bddXor, f, g);
    if (r != NULL) return(r);

    /* Here we can skip the use of cuddI, because the operands are known
    ** to be non-constant.
    */
    topf = manager->perm[f->index];
    G = Cudd_Regular(g);
    topg = manager->perm[G->index];

    /* Compute cofactors. */
    if (topf <= topg) {
        index = f->index;
        fv = cuddT(f);
        fnv = cuddE(f);
    } else {
        index = G->index;
        fv = fnv = f;
    }

    if (topg <= topf) {
        gv = cuddT(G);
        gnv = cuddE(G);
        if (Cudd_IsComplement(g)) {
            gv = Cudd_Not(gv);
            gnv = Cudd_Not(gnv);
        }
    } else {
        gv = gnv = g;
    }

    t = cuddBddXorRecur(manager, fv, gv);
    if (t == NULL) return(NULL);
    cuddRef(t);

    e = cuddBddXorRecur(manager, fnv, gnv);
    if (e == NULL) {
        Cudd_IterDerefBdd(manager, t);
        return(NULL);
    }
    cuddRef(e);

    if (t == e) {
        r = t;
    } else {
        if (Cudd_IsComplement(t)) {
            r = cuddUniqueInter(manager,(int)index,Cudd_Not(t),Cudd_Not(e));
            if (r == NULL) {
                Cudd_IterDerefBdd(manager, t);
                Cudd_IterDerefBdd(manager, e);
                return(NULL);
            }
            r = Cudd_Not(r);
        } else {
            r = cuddUniqueInter(manager,(int)index,t,e);
            if (r == NULL) {
                Cudd_IterDerefBdd(manager, t);
                Cudd_IterDerefBdd(manager, e);
                return(NULL);
            }
        }
    }
    cuddDeref(e);
    cuddDeref(t);
    cuddCacheInsert2(manager, Cudd_bddXor, f, g, r);
    return(r);

} /* end of cuddBddXorRecur */

---

Variable Documentation

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

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

FileName [cuddBddIte.c]

PackageName [cudd]

Synopsis [BDD ITE function and satellites.]

Description [External procedures included in this module:

• Cudd_bddIte()
• Cudd_bddIteConstant()
• Cudd_bddIntersect()
• Cudd_bddAnd()
• Cudd_bddOr()
• Cudd_bddNand()
• Cudd_bddNor()
• Cudd_bddXor()
• Cudd_bddXnor()
• Cudd_bddLeq()

Internal procedures included in this module:

• cuddBddIteRecur()
• cuddBddIntersectRecur()
• cuddBddAndRecur()
• cuddBddXorRecur()

Static procedures included in this module:

• bddVarToConst()
• bddVarToCanonical()
• bddVarToCanonicalSimple()

]

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 71 of file cuddBddIte.c.