/**CFile*********************************************************************** FileName [cuddZddSetop.c] PackageName [cudd] Synopsis [Set operations on ZDDs.] Description [External procedures included in this module: Internal procedures included in this module: Static procedures included in this module: ] SeeAlso [] Author [Hyong-Kyoon Shin, In-Ho Moon] 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.] ******************************************************************************/ #include "misc/util/util_hack.h" #include "cuddInt.h" ABC_NAMESPACE_IMPL_START /*---------------------------------------------------------------------------*/ /* Constant declarations */ /*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/ /* Stucture declarations */ /*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/ /* Type declarations */ /*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/ /* Variable declarations */ /*---------------------------------------------------------------------------*/ #ifndef lint static char rcsid[] DD_UNUSED = "$Id: cuddZddSetop.c,v 1.25 2004/08/13 18:04:54 fabio Exp $"; #endif /*---------------------------------------------------------------------------*/ /* Macro declarations */ /*---------------------------------------------------------------------------*/ /**AutomaticStart*************************************************************/ /*---------------------------------------------------------------------------*/ /* Static function prototypes */ /*---------------------------------------------------------------------------*/ static DdNode * zdd_subset1_aux (DdManager *zdd, DdNode *P, DdNode *zvar); static DdNode * zdd_subset0_aux (DdManager *zdd, DdNode *P, DdNode *zvar); static void zddVarToConst (DdNode *f, DdNode **gp, DdNode **hp, DdNode *base, DdNode *empty); /**AutomaticEnd***************************************************************/ /*---------------------------------------------------------------------------*/ /* Definition of exported functions */ /*---------------------------------------------------------------------------*/ /**Function******************************************************************** Synopsis [Computes the ITE of three ZDDs.] Description [Computes the ITE of three ZDDs. Returns a pointer to the result if successful; NULL otherwise.] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * Cudd_zddIte( DdManager * dd, DdNode * f, DdNode * g, DdNode * h) { DdNode *res; do { dd->reordered = 0; res = cuddZddIte(dd, f, g, h); } while (dd->reordered == 1); return(res); } /* end of Cudd_zddIte */ /**Function******************************************************************** Synopsis [Computes the union of two ZDDs.] Description [Computes the union of two ZDDs. Returns a pointer to the result if successful; NULL otherwise.] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * Cudd_zddUnion( DdManager * dd, DdNode * P, DdNode * Q) { DdNode *res; do { dd->reordered = 0; res = cuddZddUnion(dd, P, Q); } while (dd->reordered == 1); return(res); } /* end of Cudd_zddUnion */ /**Function******************************************************************** Synopsis [Computes the intersection of two ZDDs.] Description [Computes the intersection of two ZDDs. Returns a pointer to the result if successful; NULL otherwise.] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * Cudd_zddIntersect( DdManager * dd, DdNode * P, DdNode * Q) { DdNode *res; do { dd->reordered = 0; res = cuddZddIntersect(dd, P, Q); } while (dd->reordered == 1); return(res); } /* end of Cudd_zddIntersect */ /**Function******************************************************************** Synopsis [Computes the difference of two ZDDs.] Description [Computes the difference of two ZDDs. Returns a pointer to the result if successful; NULL otherwise.] SideEffects [None] SeeAlso [Cudd_zddDiffConst] ******************************************************************************/ DdNode * Cudd_zddDiff( DdManager * dd, DdNode * P, DdNode * Q) { DdNode *res; do { dd->reordered = 0; res = cuddZddDiff(dd, P, Q); } while (dd->reordered == 1); return(res); } /* end of Cudd_zddDiff */ /**Function******************************************************************** Synopsis [Performs the inclusion test for ZDDs (P implies Q).] Description [Inclusion test for ZDDs (P implies Q). No new nodes are generated by this procedure. Returns empty if true; a valid pointer different from empty or DD_NON_CONSTANT otherwise.] SideEffects [None] SeeAlso [Cudd_zddDiff] ******************************************************************************/ DdNode * Cudd_zddDiffConst( DdManager * zdd, DdNode * P, DdNode * Q) { int p_top, q_top; DdNode *empty = DD_ZERO(zdd), *t, *res; DdManager *table = zdd; statLine(zdd); if (P == empty) return(empty); if (Q == empty) return(P); if (P == Q) return(empty); /* Check cache. The cache is shared by cuddZddDiff(). */ res = cuddCacheLookup2Zdd(table, cuddZddDiff, P, Q); if (res != NULL) return(res); if (cuddIsConstant(P)) p_top = P->index; else p_top = zdd->permZ[P->index]; if (cuddIsConstant(Q)) q_top = Q->index; else q_top = zdd->permZ[Q->index]; if (p_top < q_top) { res = DD_NON_CONSTANT; } else if (p_top > q_top) { res = Cudd_zddDiffConst(zdd, P, cuddE(Q)); } else { t = Cudd_zddDiffConst(zdd, cuddT(P), cuddT(Q)); if (t != empty) res = DD_NON_CONSTANT; else res = Cudd_zddDiffConst(zdd, cuddE(P), cuddE(Q)); } cuddCacheInsert2(table, cuddZddDiff, P, Q, res); return(res); } /* end of Cudd_zddDiffConst */ /**Function******************************************************************** Synopsis [Computes the positive cofactor of a ZDD w.r.t. a variable.] Description [Computes the positive cofactor of a ZDD w.r.t. a variable. In terms of combinations, the result is the set of all combinations in which the variable is asserted. Returns a pointer to the result if successful; NULL otherwise.] SideEffects [None] SeeAlso [Cudd_zddSubset0] ******************************************************************************/ DdNode * Cudd_zddSubset1( DdManager * dd, DdNode * P, int var) { DdNode *r; do { dd->reordered = 0; r = cuddZddSubset1(dd, P, var); } while (dd->reordered == 1); return(r); } /* end of Cudd_zddSubset1 */ /**Function******************************************************************** Synopsis [Computes the negative cofactor of a ZDD w.r.t. a variable.] Description [Computes the negative cofactor of a ZDD w.r.t. a variable. In terms of combinations, the result is the set of all combinations in which the variable is negated. Returns a pointer to the result if successful; NULL otherwise.] SideEffects [None] SeeAlso [Cudd_zddSubset1] ******************************************************************************/ DdNode * Cudd_zddSubset0( DdManager * dd, DdNode * P, int var) { DdNode *r; do { dd->reordered = 0; r = cuddZddSubset0(dd, P, var); } while (dd->reordered == 1); return(r); } /* end of Cudd_zddSubset0 */ /**Function******************************************************************** Synopsis [Substitutes a variable with its complement in a ZDD.] Description [Substitutes a variable with its complement in a ZDD. returns a pointer to the result if successful; NULL otherwise.] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * Cudd_zddChange( DdManager * dd, DdNode * P, int var) { DdNode *res; if ((unsigned int) var >= CUDD_MAXINDEX - 1) return(NULL); do { dd->reordered = 0; res = cuddZddChange(dd, P, var); } while (dd->reordered == 1); return(res); } /* end of Cudd_zddChange */ /*---------------------------------------------------------------------------*/ /* Definition of internal functions */ /*---------------------------------------------------------------------------*/ /**Function******************************************************************** Synopsis [Performs the recursive step of Cudd_zddIte.] Description [] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * cuddZddIte( DdManager * dd, DdNode * f, DdNode * g, DdNode * h) { DdNode *tautology, *empty; DdNode *r,*Gv,*Gvn,*Hv,*Hvn,*t,*e; unsigned int topf,topg,toph,v,top; int index; statLine(dd); /* Trivial cases. */ /* One variable cases. */ if (f == (empty = DD_ZERO(dd))) { /* ITE(0,G,H) = H */ return(h); } topf = cuddIZ(dd,f->index); topg = cuddIZ(dd,g->index); toph = cuddIZ(dd,h->index); v = ddMin(topg,toph); top = ddMin(topf,v); tautology = (top == CUDD_MAXINDEX) ? DD_ONE(dd) : dd->univ[top]; if (f == tautology) { /* ITE(1,G,H) = G */ return(g); } /* From now on, f is known to not be a constant. */ zddVarToConst(f,&g,&h,tautology,empty); /* Check remaining one variable cases. */ if (g == h) { /* ITE(F,G,G) = G */ return(g); } if (g == tautology) { /* ITE(F,1,0) = F */ if (h == empty) return(f); } /* Check cache. */ r = cuddCacheLookupZdd(dd,DD_ZDD_ITE_TAG,f,g,h); if (r != NULL) { return(r); } /* Recompute these because they may have changed in zddVarToConst. */ topg = cuddIZ(dd,g->index); toph = cuddIZ(dd,h->index); v = ddMin(topg,toph); if (topf < v) { r = cuddZddIte(dd,cuddE(f),g,h); if (r == NULL) return(NULL); } else if (topf > v) { if (topg > v) { Gvn = g; index = h->index; } else { Gvn = cuddE(g); index = g->index; } if (toph > v) { Hv = empty; Hvn = h; } else { Hv = cuddT(h); Hvn = cuddE(h); } e = cuddZddIte(dd,f,Gvn,Hvn); if (e == NULL) return(NULL); cuddRef(e); r = cuddZddGetNode(dd,index,Hv,e); if (r == NULL) { Cudd_RecursiveDerefZdd(dd,e); return(NULL); } cuddDeref(e); } else { index = f->index; if (topg > v) { Gv = empty; Gvn = g; } else { Gv = cuddT(g); Gvn = cuddE(g); } if (toph > v) { Hv = empty; Hvn = h; } else { Hv = cuddT(h); Hvn = cuddE(h); } e = cuddZddIte(dd,cuddE(f),Gvn,Hvn); if (e == NULL) return(NULL); cuddRef(e); t = cuddZddIte(dd,cuddT(f),Gv,Hv); if (t == NULL) { Cudd_RecursiveDerefZdd(dd,e); return(NULL); } cuddRef(t); r = cuddZddGetNode(dd,index,t,e); if (r == NULL) { Cudd_RecursiveDerefZdd(dd,e); Cudd_RecursiveDerefZdd(dd,t); return(NULL); } cuddDeref(t); cuddDeref(e); } cuddCacheInsert(dd,DD_ZDD_ITE_TAG,f,g,h,r); return(r); } /* end of cuddZddIte */ /**Function******************************************************************** Synopsis [Performs the recursive step of Cudd_zddUnion.] Description [] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * cuddZddUnion( DdManager * zdd, DdNode * P, DdNode * Q) { int p_top, q_top; DdNode *empty = DD_ZERO(zdd), *t, *e, *res; DdManager *table = zdd; statLine(zdd); if (P == empty) return(Q); if (Q == empty) return(P); if (P == Q) return(P); /* Check cache */ res = cuddCacheLookup2Zdd(table, cuddZddUnion, P, Q); if (res != NULL) return(res); if (cuddIsConstant(P)) p_top = P->index; else p_top = zdd->permZ[P->index]; if (cuddIsConstant(Q)) q_top = Q->index; else q_top = zdd->permZ[Q->index]; if (p_top < q_top) { e = cuddZddUnion(zdd, cuddE(P), Q); if (e == NULL) return (NULL); cuddRef(e); res = cuddZddGetNode(zdd, P->index, cuddT(P), e); if (res == NULL) { Cudd_RecursiveDerefZdd(table, e); return(NULL); } cuddDeref(e); } else if (p_top > q_top) { e = cuddZddUnion(zdd, P, cuddE(Q)); if (e == NULL) return(NULL); cuddRef(e); res = cuddZddGetNode(zdd, Q->index, cuddT(Q), e); if (res == NULL) { Cudd_RecursiveDerefZdd(table, e); return(NULL); } cuddDeref(e); } else { t = cuddZddUnion(zdd, cuddT(P), cuddT(Q)); if (t == NULL) return(NULL); cuddRef(t); e = cuddZddUnion(zdd, cuddE(P), cuddE(Q)); if (e == NULL) { Cudd_RecursiveDerefZdd(table, t); return(NULL); } cuddRef(e); res = cuddZddGetNode(zdd, P->index, t, e); if (res == NULL) { Cudd_RecursiveDerefZdd(table, t); Cudd_RecursiveDerefZdd(table, e); return(NULL); } cuddDeref(t); cuddDeref(e); } cuddCacheInsert2(table, cuddZddUnion, P, Q, res); return(res); } /* end of cuddZddUnion */ /**Function******************************************************************** Synopsis [Performs the recursive step of Cudd_zddIntersect.] Description [] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * cuddZddIntersect( DdManager * zdd, DdNode * P, DdNode * Q) { int p_top, q_top; DdNode *empty = DD_ZERO(zdd), *t, *e, *res; DdManager *table = zdd; statLine(zdd); if (P == empty) return(empty); if (Q == empty) return(empty); if (P == Q) return(P); /* Check cache. */ res = cuddCacheLookup2Zdd(table, cuddZddIntersect, P, Q); if (res != NULL) return(res); if (cuddIsConstant(P)) p_top = P->index; else p_top = zdd->permZ[P->index]; if (cuddIsConstant(Q)) q_top = Q->index; else q_top = zdd->permZ[Q->index]; if (p_top < q_top) { res = cuddZddIntersect(zdd, cuddE(P), Q); if (res == NULL) return(NULL); } else if (p_top > q_top) { res = cuddZddIntersect(zdd, P, cuddE(Q)); if (res == NULL) return(NULL); } else { t = cuddZddIntersect(zdd, cuddT(P), cuddT(Q)); if (t == NULL) return(NULL); cuddRef(t); e = cuddZddIntersect(zdd, cuddE(P), cuddE(Q)); if (e == NULL) { Cudd_RecursiveDerefZdd(table, t); return(NULL); } cuddRef(e); res = cuddZddGetNode(zdd, P->index, t, e); if (res == NULL) { Cudd_RecursiveDerefZdd(table, t); Cudd_RecursiveDerefZdd(table, e); return(NULL); } cuddDeref(t); cuddDeref(e); } cuddCacheInsert2(table, cuddZddIntersect, P, Q, res); return(res); } /* end of cuddZddIntersect */ /**Function******************************************************************** Synopsis [Performs the recursive step of Cudd_zddDiff.] Description [] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * cuddZddDiff( DdManager * zdd, DdNode * P, DdNode * Q) { int p_top, q_top; DdNode *empty = DD_ZERO(zdd), *t, *e, *res; DdManager *table = zdd; statLine(zdd); if (P == empty) return(empty); if (Q == empty) return(P); if (P == Q) return(empty); /* Check cache. The cache is shared by Cudd_zddDiffConst(). */ res = cuddCacheLookup2Zdd(table, cuddZddDiff, P, Q); if (res != NULL && res != DD_NON_CONSTANT) return(res); if (cuddIsConstant(P)) p_top = P->index; else p_top = zdd->permZ[P->index]; if (cuddIsConstant(Q)) q_top = Q->index; else q_top = zdd->permZ[Q->index]; if (p_top < q_top) { e = cuddZddDiff(zdd, cuddE(P), Q); if (e == NULL) return(NULL); cuddRef(e); res = cuddZddGetNode(zdd, P->index, cuddT(P), e); if (res == NULL) { Cudd_RecursiveDerefZdd(table, e); return(NULL); } cuddDeref(e); } else if (p_top > q_top) { res = cuddZddDiff(zdd, P, cuddE(Q)); if (res == NULL) return(NULL); } else { t = cuddZddDiff(zdd, cuddT(P), cuddT(Q)); if (t == NULL) return(NULL); cuddRef(t); e = cuddZddDiff(zdd, cuddE(P), cuddE(Q)); if (e == NULL) { Cudd_RecursiveDerefZdd(table, t); return(NULL); } cuddRef(e); res = cuddZddGetNode(zdd, P->index, t, e); if (res == NULL) { Cudd_RecursiveDerefZdd(table, t); Cudd_RecursiveDerefZdd(table, e); return(NULL); } cuddDeref(t); cuddDeref(e); } cuddCacheInsert2(table, cuddZddDiff, P, Q, res); return(res); } /* end of cuddZddDiff */ /**Function******************************************************************** Synopsis [Performs the recursive step of Cudd_zddChange.] Description [] SideEffects [None] SeeAlso [] ******************************************************************************/ DdNode * cuddZddChangeAux( DdManager * zdd, DdNode * P, DdNode * zvar) { int top_var, level; DdNode *res, *t, *e; DdNode *base = DD_ONE(zdd); DdNode *empty = DD_ZERO(zdd); statLine(zdd); if (P == empty) return(empty); if (P == base) return(zvar); /* Check cache. */ res = cuddCacheLookup2Zdd(zdd, cuddZddChangeAux, P, zvar); if (res != NULL) return(res); top_var = zdd->permZ[P->index]; level = zdd->permZ[zvar->index]; if (top_var > level) { res = cuddZddGetNode(zdd, zvar->index, P, DD_ZERO(zdd)); if (res == NULL) return(NULL); } else if (top_var == level) { res = cuddZddGetNode(zdd, zvar->index, cuddE(P), cuddT(P)); if (res == NULL) return(NULL); } else { t = cuddZddChangeAux(zdd, cuddT(P), zvar); if (t == NULL) return(NULL); cuddRef(t); e = cuddZddChangeAux(zdd, cuddE(P), zvar); if (e == NULL) { Cudd_RecursiveDerefZdd(zdd, t); return(NULL); } cuddRef(e); res = cuddZddGetNode(zdd, P->index, t, e); if (res == NULL) { Cudd_RecursiveDerefZdd(zdd, t); Cudd_RecursiveDerefZdd(zdd, e); return(NULL); } cuddDeref(t); cuddDeref(e); } cuddCacheInsert2(zdd, cuddZddChangeAux, P, zvar, res); return(res); } /* end of cuddZddChangeAux */ /**Function******************************************************************** Synopsis [Computes the positive cofactor of a ZDD w.r.t. a variable.] Description [Computes the positive cofactor of a ZDD w.r.t. a variable. In terms of combinations, the result is the set of all combinations in which the variable is asserted. Returns a pointer to the result if successful; NULL otherwise. cuddZddSubset1 performs the same function as Cudd_zddSubset1, but does not restart if reordering has taken place. Therefore it can be called from within a recursive procedure.] SideEffects [None] SeeAlso [cuddZddSubset0 Cudd_zddSubset1] ******************************************************************************/ DdNode * cuddZddSubset1( DdManager * dd, DdNode * P, int var) { DdNode *zvar, *r; DdNode *base, *empty; base = DD_ONE(dd); empty = DD_ZERO(dd); zvar = cuddUniqueInterZdd(dd, var, base, empty); if (zvar == NULL) { return(NULL); } else { cuddRef(zvar); r = zdd_subset1_aux(dd, P, zvar); if (r == NULL) { Cudd_RecursiveDerefZdd(dd, zvar); return(NULL); } cuddRef(r); Cudd_RecursiveDerefZdd(dd, zvar); } cuddDeref(r); return(r); } /* end of cuddZddSubset1 */ /**Function******************************************************************** Synopsis [Computes the negative cofactor of a ZDD w.r.t. a variable.] Description [Computes the negative cofactor of a ZDD w.r.t. a variable. In terms of combinations, the result is the set of all combinations in which the variable is negated. Returns a pointer to the result if successful; NULL otherwise. cuddZddSubset0 performs the same function as Cudd_zddSubset0, but does not restart if reordering has taken place. Therefore it can be called from within a recursive procedure.] SideEffects [None] SeeAlso [cuddZddSubset1 Cudd_zddSubset0] ******************************************************************************/ DdNode * cuddZddSubset0( DdManager * dd, DdNode * P, int var) { DdNode *zvar, *r; DdNode *base, *empty; base = DD_ONE(dd); empty = DD_ZERO(dd); zvar = cuddUniqueInterZdd(dd, var, base, empty); if (zvar == NULL) { return(NULL); } else { cuddRef(zvar); r = zdd_subset0_aux(dd, P, zvar); if (r == NULL) { Cudd_RecursiveDerefZdd(dd, zvar); return(NULL); } cuddRef(r); Cudd_RecursiveDerefZdd(dd, zvar); } cuddDeref(r); return(r); } /* end of cuddZddSubset0 */ /**Function******************************************************************** Synopsis [Substitutes a variable with its complement in a ZDD.] Description [Substitutes a variable with its complement in a ZDD. returns a pointer to the result if successful; NULL otherwise. cuddZddChange performs the same function as Cudd_zddChange, but does not restart if reordering has taken place. Therefore it can be called from within a recursive procedure.] SideEffects [None] SeeAlso [Cudd_zddChange] ******************************************************************************/ DdNode * cuddZddChange( DdManager * dd, DdNode * P, int var) { DdNode *zvar, *res; zvar = cuddUniqueInterZdd(dd, var, DD_ONE(dd), DD_ZERO(dd)); if (zvar == NULL) return(NULL); cuddRef(zvar); res = cuddZddChangeAux(dd, P, zvar); if (res == NULL) { Cudd_RecursiveDerefZdd(dd,zvar); return(NULL); } cuddRef(res); Cudd_RecursiveDerefZdd(dd,zvar); cuddDeref(res); return(res); } /* end of cuddZddChange */ /*---------------------------------------------------------------------------*/ /* Definition of static functions */ /*---------------------------------------------------------------------------*/ /**Function******************************************************************** Synopsis [Performs the recursive step of Cudd_zddSubset1.] Description [] SideEffects [None] SeeAlso [] ******************************************************************************/ static DdNode * zdd_subset1_aux( DdManager * zdd, DdNode * P, DdNode * zvar) { int top_var, level; DdNode *res, *t, *e; DdNode *empty; statLine(zdd); empty = DD_ZERO(zdd); /* Check cache. */ res = cuddCacheLookup2Zdd(zdd, zdd_subset1_aux, P, zvar); if (res != NULL) return(res); if (cuddIsConstant(P)) { res = empty; cuddCacheInsert2(zdd, zdd_subset1_aux, P, zvar, res); return(res); } top_var = zdd->permZ[P->index]; level = zdd->permZ[zvar->index]; if (top_var > level) { res = empty; } else if (top_var == level) { res = cuddT(P); } else { t = zdd_subset1_aux(zdd, cuddT(P), zvar); if (t == NULL) return(NULL); cuddRef(t); e = zdd_subset1_aux(zdd, cuddE(P), zvar); if (e == NULL) { Cudd_RecursiveDerefZdd(zdd, t); return(NULL); } cuddRef(e); res = cuddZddGetNode(zdd, P->index, t, e); if (res == NULL) { Cudd_RecursiveDerefZdd(zdd, t); Cudd_RecursiveDerefZdd(zdd, e); return(NULL); } cuddDeref(t); cuddDeref(e); } cuddCacheInsert2(zdd, zdd_subset1_aux, P, zvar, res); return(res); } /* end of zdd_subset1_aux */ /**Function******************************************************************** Synopsis [Performs the recursive step of Cudd_zddSubset0.] Description [] SideEffects [None] SeeAlso [] ******************************************************************************/ static DdNode * zdd_subset0_aux( DdManager * zdd, DdNode * P, DdNode * zvar) { int top_var, level; DdNode *res, *t, *e; statLine(zdd); /* Check cache. */ res = cuddCacheLookup2Zdd(zdd, zdd_subset0_aux, P, zvar); if (res != NULL) return(res); if (cuddIsConstant(P)) { res = P; cuddCacheInsert2(zdd, zdd_subset0_aux, P, zvar, res); return(res); } top_var = zdd->permZ[P->index]; level = zdd->permZ[zvar->index]; if (top_var > level) { res = P; } else if (top_var == level) { res = cuddE(P); } else { t = zdd_subset0_aux(zdd, cuddT(P), zvar); if (t == NULL) return(NULL); cuddRef(t); e = zdd_subset0_aux(zdd, cuddE(P), zvar); if (e == NULL) { Cudd_RecursiveDerefZdd(zdd, t); return(NULL); } cuddRef(e); res = cuddZddGetNode(zdd, P->index, t, e); if (res == NULL) { Cudd_RecursiveDerefZdd(zdd, t); Cudd_RecursiveDerefZdd(zdd, e); return(NULL); } cuddDeref(t); cuddDeref(e); } cuddCacheInsert2(zdd, zdd_subset0_aux, P, zvar, res); return(res); } /* end of zdd_subset0_aux */ /**Function******************************************************************** Synopsis [Replaces variables with constants if possible (part of canonical form).] Description [] SideEffects [None] SeeAlso [] ******************************************************************************/ static void zddVarToConst( DdNode * f, DdNode ** gp, DdNode ** hp, DdNode * base, DdNode * empty) { DdNode *g = *gp; DdNode *h = *hp; if (f == g) { /* ITE(F,F,H) = ITE(F,1,H) = F + H */ *gp = base; } if (f == h) { /* ITE(F,G,F) = ITE(F,G,0) = F * G */ *hp = empty; } } /* end of zddVarToConst */ ABC_NAMESPACE_IMPL_END