source: vis_dev/glu-2.3/src/cuBdd/cuddLiteral.c @ 21

Last change on this file since 21 was 13, checked in by cecile, 13 years ago

library glu 2.3
File size: 8.5 KB
Line 
1/**CFile***********************************************************************
2
3  FileName    [cuddLiteral.c]
4
5  PackageName [cudd]
6
7  Synopsis    [Functions for manipulation of literal sets represented by
8  BDDs.]
9
10  Description [External procedures included in this file:
11                <ul>
12                <li> Cudd_bddLiteralSetIntersection()
13                </ul>
14            Internal procedures included in this file:
15                <ul>
16                <li> cuddBddLiteralSetIntersectionRecur()
17                </ul>]
18
19  Author      [Fabio Somenzi]
20
21  Copyright   [Copyright (c) 1995-2004, Regents of the University of Colorado
22
23  All rights reserved.
24
25  Redistribution and use in source and binary forms, with or without
26  modification, are permitted provided that the following conditions
27  are met:
28
29  Redistributions of source code must retain the above copyright
30  notice, this list of conditions and the following disclaimer.
31
32  Redistributions in binary form must reproduce the above copyright
33  notice, this list of conditions and the following disclaimer in the
34  documentation and/or other materials provided with the distribution.
35
36  Neither the name of the University of Colorado nor the names of its
37  contributors may be used to endorse or promote products derived from
38  this software without specific prior written permission.
39
40  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
41  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
42  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
43  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
44  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
45  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
46  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
47  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
48  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
50  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
51  POSSIBILITY OF SUCH DAMAGE.]
52
53******************************************************************************/
54
55#include "util.h"
56#include "cuddInt.h"
57
58
59/*---------------------------------------------------------------------------*/
60/* Constant declarations                                                     */
61/*---------------------------------------------------------------------------*/
62
63/*---------------------------------------------------------------------------*/
64/* Stucture declarations                                                     */
65/*---------------------------------------------------------------------------*/
66
67/*---------------------------------------------------------------------------*/
68/* Type declarations                                                         */
69/*---------------------------------------------------------------------------*/
70
71/*---------------------------------------------------------------------------*/
72/* Variable declarations                                                     */
73/*---------------------------------------------------------------------------*/
74
75#ifndef lint
76static char rcsid[] DD_UNUSED = "$Id: cuddLiteral.c,v 1.8 2004/08/13 18:04:50 fabio Exp $";
77#endif
78
79/*---------------------------------------------------------------------------*/
80/* Macro declarations                                                        */
81/*---------------------------------------------------------------------------*/
82
83/**AutomaticStart*************************************************************/
84
85/*---------------------------------------------------------------------------*/
86/* Static function prototypes                                                */
87/*---------------------------------------------------------------------------*/
88
89
90/**AutomaticEnd***************************************************************/
91
92
93/*---------------------------------------------------------------------------*/
94/* Definition of exported functions                                          */
95/*---------------------------------------------------------------------------*/
96
97
98/**Function********************************************************************
99
100  Synopsis    [Computes the intesection of two sets of literals
101  represented as BDDs.]
102
103  Description [Computes the intesection of two sets of literals
104  represented as BDDs. Each set is represented as a cube of the
105  literals in the set. The empty set is represented by the constant 1.
106  No variable can be simultaneously present in both phases in a set.
107  Returns a pointer to the BDD representing the intersected sets, if
108  successful; NULL otherwise.]
109
110  SideEffects [None]
111
112******************************************************************************/
113DdNode *
114Cudd_bddLiteralSetIntersection(
115  DdManager * dd,
116  DdNode * f,
117  DdNode * g)
118{
119    DdNode *res;
120
121    do {
122        dd->reordered = 0;
123        res = cuddBddLiteralSetIntersectionRecur(dd,f,g);
124    } while (dd->reordered == 1);
125    return(res);
126
127} /* end of Cudd_bddLiteralSetIntersection */
128
129
130/*---------------------------------------------------------------------------*/
131/* Definition of internal functions                                          */
132/*---------------------------------------------------------------------------*/
133
134
135/**Function********************************************************************
136
137  Synopsis    [Performs the recursive step of
138  Cudd_bddLiteralSetIntersection.]
139
140  Description [Performs the recursive step of
141  Cudd_bddLiteralSetIntersection. Scans the cubes for common variables,
142  and checks whether they agree in phase.  Returns a pointer to the
143  resulting cube if successful; NULL otherwise.]
144
145  SideEffects [None]
146
147******************************************************************************/
148DdNode *
149cuddBddLiteralSetIntersectionRecur(
150  DdManager * dd,
151  DdNode * f,
152  DdNode * g)
153{
154    DdNode *res, *tmp;
155    DdNode *F, *G;
156    DdNode *fc, *gc;
157    DdNode *one;
158    DdNode *zero;
159    unsigned int topf, topg, comple;
160    int phasef, phaseg;
161
162    statLine(dd);
163    if (f == g) return(f);
164
165    F = Cudd_Regular(f);
166    G = Cudd_Regular(g);
167    one = DD_ONE(dd);
168
169    /* Here f != g. If F == G, then f and g are complementary.
170    ** Since they are two cubes, this case only occurs when f == v,
171    ** g == v', and v is a variable or its complement.
172    */
173    if (F == G) return(one);
174
175    zero = Cudd_Not(one);
176    topf = cuddI(dd,F->index);
177    topg = cuddI(dd,G->index);
178    /* Look for a variable common to both cubes. If there are none, this
179    ** loop will stop when the constant node is reached in both cubes.
180    */
181    while (topf != topg) {
182        if (topf < topg) {      /* move down on f */
183            comple = f != F;
184            f = cuddT(F);
185            if (comple) f = Cudd_Not(f);
186            if (f == zero) {
187                f = cuddE(F);
188                if (comple) f = Cudd_Not(f);
189            }
190            F = Cudd_Regular(f);
191            topf = cuddI(dd,F->index);
192        } else if (topg < topf) {
193            comple = g != G;
194            g = cuddT(G);
195            if (comple) g = Cudd_Not(g);
196            if (g == zero) {
197                g = cuddE(G);
198                if (comple) g = Cudd_Not(g);
199            }
200            G = Cudd_Regular(g);
201            topg = cuddI(dd,G->index);
202        }
203    }
204
205    /* At this point, f == one <=> g == 1. It suffices to test one of them. */
206    if (f == one) return(one);
207
208    res = cuddCacheLookup2(dd,Cudd_bddLiteralSetIntersection,f,g);
209    if (res != NULL) {
210        return(res);
211    }
212
213    /* Here f and g are both non constant and have the same top variable. */
214    comple = f != F;
215    fc = cuddT(F);
216    phasef = 1;
217    if (comple) fc = Cudd_Not(fc);
218    if (fc == zero) {
219        fc = cuddE(F);
220        phasef = 0;
221        if (comple) fc = Cudd_Not(fc);
222    }
223    comple = g != G;
224    gc = cuddT(G);
225    phaseg = 1;
226    if (comple) gc = Cudd_Not(gc);
227    if (gc == zero) {
228        gc = cuddE(G);
229        phaseg = 0;
230        if (comple) gc = Cudd_Not(gc);
231    }
232
233    tmp = cuddBddLiteralSetIntersectionRecur(dd,fc,gc);
234    if (tmp == NULL) {
235        return(NULL);
236    }
237
238    if (phasef != phaseg) {
239        res = tmp;
240    } else {
241        cuddRef(tmp);
242        if (phasef == 0) {
243            res = cuddBddAndRecur(dd,Cudd_Not(dd->vars[F->index]),tmp);
244        } else {
245            res = cuddBddAndRecur(dd,dd->vars[F->index],tmp);
246        }
247        if (res == NULL) {
248            Cudd_RecursiveDeref(dd,tmp);
249            return(NULL);
250        }
251        cuddDeref(tmp); /* Just cuddDeref, because it is included in result */
252    }
253
254    cuddCacheInsert2(dd,Cudd_bddLiteralSetIntersection,f,g,res);
255
256    return(res);
257
258} /* end of cuddBddLiteralSetIntersectionRecur */
259
260
261/*---------------------------------------------------------------------------*/
262/* Definition of static functions                                            */
263/*---------------------------------------------------------------------------*/
264
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