/**Function********************************************************************
Synopsis [Performs the recursive steps of Cudd_bddBoleanDiff.]
Description [Performs the recursive steps of Cudd_bddBoleanDiff.
Returns the BDD obtained by XORing the cofactors of f with respect to
var if successful; NULL otherwise. Exploits the fact that dF/dx =
dF'/dx.]
SideEffects [None]
SeeAlso []
******************************************************************************/
DdNode *
cuddBddBooleanDiffRecur(
DdManager * manager,
DdNode * f,
DdNode * var)
{
DdNode *T, *E, *res, *res1, *res2;
statLine(manager);
if (cuddI(manager,f->index) > manager->perm[var->index]) {
/* f does not depend on var. */
return(Cudd_Not(DD_ONE(manager)));
}
/* From now on, f is non-constant. */
/* If the two indices are the same, so are their levels. */
if (f->index == var->index) {
res = cuddBddXorRecur(manager, cuddT(f), cuddE(f));
return(res);
}
/* From now on, cuddI(manager,f->index) < cuddI(manager,cube->index). */
/* Check the cache. */
res = cuddCacheLookup2(manager, cuddBddBooleanDiffRecur, f, var);
if (res != NULL) {
return(res);
}
/* Compute the cofactors of f. */
T = cuddT(f); E = cuddE(f);
res1 = cuddBddBooleanDiffRecur(manager, T, var);
if (res1 == NULL) return(NULL);
cuddRef(res1);
res2 = cuddBddBooleanDiffRecur(manager, Cudd_Regular(E), var);
if (res2 == NULL) {
Cudd_IterDerefBdd(manager, res1);
return(NULL);
}
cuddRef(res2);
/* ITE takes care of possible complementation of res1 and of the
** case in which res1 == res2. */
res = cuddBddIteRecur(manager, manager->vars[f->index], res1, res2);
if (res == NULL) {
Cudd_IterDerefBdd(manager, res1);
Cudd_IterDerefBdd(manager, res2);
return(NULL);
}
cuddDeref(res1);
cuddDeref(res2);
cuddCacheInsert2(manager, cuddBddBooleanDiffRecur, f, var, res);
return(res);
} /* end of cuddBddBooleanDiffRecur */
/**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]
******************************************************************************/
DdNode *
Cudd_bddXnor(
DdManager * dd,
DdNode * f,
DdNode * g)
{
DdNode *res;
do {
dd->reordered = 0;
res = cuddBddXorRecur(dd,f,Cudd_Not(g));
} while (dd->reordered == 1);
return(res);
} /* end of Cudd_bddXnor */
/**Function********************************************************************
Synopsis [Computes the exclusive NOR of two BDDs f and g. Returns
NULL if too many nodes are required.]
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 or more new nodes than <code>limit</code> are
required.]
SideEffects [None]
SeeAlso [Cudd_bddXnor]
******************************************************************************/
DdNode *
Cudd_bddXnorLimit(
DdManager * dd,
DdNode * f,
DdNode * g,
unsigned int limit)
{
DdNode *res;
unsigned int saveLimit = dd->maxLive;
dd->maxLive = (dd->keys - dd->dead) + (dd->keysZ - dd->deadZ) + limit;
do {
dd->reordered = 0;
res = cuddBddXorRecur(dd,f,Cudd_Not(g));
} while (dd->reordered == 1);
dd->maxLive = saveLimit;
return(res);
} /* end of Cudd_bddXnorLimit */
/**Function********************************************************************
Synopsis [Takes the exclusive OR of two BDDs and simultaneously abstracts the
variables in cube.]
Description [Takes the exclusive OR of two BDDs and simultaneously abstracts
the variables in cube. The variables are existentially abstracted. Returns a
pointer to the result is successful; NULL otherwise.]
SideEffects [None]
SeeAlso [Cudd_bddAndAbstract]
******************************************************************************/
DdNode *
cuddBddXorExistAbstractRecur(
DdManager * manager,
DdNode * f,
DdNode * g,
DdNode * cube)
{
DdNode *F, *fv, *fnv, *G, *gv, *gnv;
DdNode *one, *zero, *r, *t, *e, *Cube;
unsigned int topf, topg, topcube, top, 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 (cube == one) {
return(cuddBddXorRecur(manager, f, g));
}
if (f == one) {
return(cuddBddExistAbstractRecur(manager, Cudd_Not(g), cube));
}
if (g == one) {
return(cuddBddExistAbstractRecur(manager, Cudd_Not(f), cube));
}
if (f == zero) {
return(cuddBddExistAbstractRecur(manager, g, cube));
}
if (g == zero) {
return(cuddBddExistAbstractRecur(manager, f, cube));
}
/* At this point f, g, and cube are not constant. */
if (f > g) { /* Try to increase cache efficiency. */
DdNode *tmp = f;
f = g;
g = tmp;
}
/* Check cache. */
r = cuddCacheLookup(manager, DD_BDD_XOR_EXIST_ABSTRACT_TAG, f, g, cube);
if (r != NULL) {
return(r);
}
/* Here we can skip the use of cuddI, because the operands are known
** to be non-constant.
*/
F = Cudd_Regular(f);
topf = manager->perm[F->index];
G = Cudd_Regular(g);
topg = manager->perm[G->index];
top = ddMin(topf, topg);
topcube = manager->perm[cube->index];
if (topcube < top) {
return(cuddBddXorExistAbstractRecur(manager, f, g, cuddT(cube)));
}
/* Now, topcube >= top. */
if (topf == top) {
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 == top) {
gv = cuddT(G);
gnv = cuddE(G);
if (Cudd_IsComplement(g)) {
gv = Cudd_Not(gv);
gnv = Cudd_Not(gnv);
}
} else {
gv = gnv = g;
}
if (topcube == top) {
Cube = cuddT(cube);
} else {
Cube = cube;
}
t = cuddBddXorExistAbstractRecur(manager, fv, gv, Cube);
if (t == NULL) return(NULL);
/* Special case: 1 OR anything = 1. Hence, no need to compute
** the else branch if t is 1.
*/
if (t == one && topcube == top) {
cuddCacheInsert(manager, DD_BDD_XOR_EXIST_ABSTRACT_TAG, f, g, cube, one);
return(one);
}
cuddRef(t);
e = cuddBddXorExistAbstractRecur(manager, fnv, gnv, Cube);
if (e == NULL) {
Cudd_IterDerefBdd(manager, t);
return(NULL);
}
cuddRef(e);
if (topcube == top) { /* abstract */
r = cuddBddAndRecur(manager, Cudd_Not(t), Cudd_Not(e));
if (r == NULL) {
Cudd_IterDerefBdd(manager, t);
Cudd_IterDerefBdd(manager, e);
return(NULL);
}
r = Cudd_Not(r);
cuddRef(r);
Cudd_IterDerefBdd(manager, t);
Cudd_IterDerefBdd(manager, e);
cuddDeref(r);
} else if (t == e) {
r = t;
cuddDeref(t);
cuddDeref(e);
} 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);
}
cuddCacheInsert(manager, DD_BDD_XOR_EXIST_ABSTRACT_TAG, f, g, cube, r);
return (r);
} /* end of cuddBddXorExistAbstractRecur */
/**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 []
******************************************************************************/
DdNode *
cuddBddIteRecur(
DdManager * dd,
DdNode * f,
DdNode * g,
DdNode * h)
{
DdNode *one, *zero, *res;
DdNode *r, *Fv, *Fnv, *Gv, *Gnv, *H, *Hv, *Hnv, *t, *e;
unsigned int topf, topg, toph, v;
int index = -1;
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 */
/**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]
******************************************************************************/
DdNode *
cuddBddXorRecur(
DdManager * manager,
DdNode * f,
DdNode * g)
{
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 (cuddF2L(f) > cuddF2L(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 */
