src/cuBdd/cuddInteract.c File Reference

#include "util.h"
#include "cuddInt.h"
Include dependency graph for cuddInteract.c:

Go to the source code of this file.

Defines

#define BPL   32
#define LOGBPL   5

Functions

static void ddSuppInteract (DdNode *f, int *support)
static void ddClearLocal (DdNode *f)
static void ddUpdateInteract (DdManager *table, int *support)
static void ddClearGlobal (DdManager *table)
void cuddSetInteract (DdManager *table, int x, int y)
int cuddTestInteract (DdManager *table, int x, int y)
int cuddInitInteract (DdManager *table)

Variables

static char rcsid[] DD_UNUSED = "$Id: cuddInteract.c,v 1.12 2004/08/13 18:04:49 fabio Exp $"

Define Documentation

#define BPL   32

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

FileName [cuddInteract.c]

PackageName [cudd]

Synopsis [Functions to manipulate the variable interaction matrix.]

Description [Internal procedures included in this file:

Static procedures included in this file:

The interaction matrix tells whether two variables are both in the support of some function of the DD. The main use of the interaction matrix is in the in-place swapping. Indeed, if two variables do not interact, there is no arc connecting the two layers; therefore, the swap can be performed in constant time, without scanning the subtables. Another use of the interaction matrix is in the computation of the lower bounds for sifting. Finally, the interaction matrix can be used to speed up aggregation checks in symmetric and group sifting.

The computation of the interaction matrix is done with a series of depth-first searches. The searches start from those nodes that have only external references. The matrix is stored as a packed array of bits; since it is symmetric, only the upper triangle is kept in memory. As a final remark, we note that there may be variables that do intercat, but that for a given variable order have no arc connecting their layers when they are adjacent.]

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 88 of file cuddInteract.c.

#define LOGBPL   5

Definition at line 89 of file cuddInteract.c.

Function Documentation

int cuddInitInteract ( DdManager *  table  ) 

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

Synopsis [Initializes the interaction matrix.]

Description [Initializes the interaction matrix. The interaction matrix is implemented as a bit vector storing the upper triangle of the symmetric interaction matrix. The bit vector is kept in an array of long integers. The computation is based on a series of depth-first searches, one for each root of the DAG. Two flags are needed: The local visited flag uses the LSB of the then pointer. The global visited flag uses the LSB of the next pointer. Returns 1 if successful; 0 otherwise.]

SideEffects [None]

SeeAlso []

Definition at line 233 of file cuddInteract.c.

00235 {
00236     int i,j,k;
00237     int words;
00238     long *interact;
00239     int *support;
00240     DdNode *f;
00241     DdNode *sentinel = &(table->sentinel);
00242     DdNodePtr *nodelist;
00243     int slots;
00244     int n = table->size;
00245 
00246     words = ((n * (n-1)) >> (1 + LOGBPL)) + 1;
00247     table->interact = interact = ALLOC(long,words);
00248     if (interact == NULL) {
00249         table->errorCode = CUDD_MEMORY_OUT;
00250         return(0);
00251     }
00252     for (i = 0; i < words; i++) {
00253         interact[i] = 0;
00254     }
00255 
00256     support = ALLOC(int,n);
00257     if (support == NULL) {
00258         table->errorCode = CUDD_MEMORY_OUT;
00259         FREE(interact);
00260         return(0);
00261     }
00262 
00263     for (i = 0; i < n; i++) {
00264         nodelist = table->subtables[i].nodelist;
00265         slots = table->subtables[i].slots;
00266         for (j = 0; j < slots; j++) {
00267             f = nodelist[j];
00268             while (f != sentinel) {
00269                 /* A node is a root of the DAG if it cannot be
00270                 ** reached by nodes above it. If a node was never
00271                 ** reached during the previous depth-first searches,
00272                 ** then it is a root, and we start a new depth-first
00273                 ** search from it.
00274                 */
00275                 if (!Cudd_IsComplement(f->next)) {
00276                     for (k = 0; k < n; k++) {
00277                         support[k] = 0;
00278                     }
00279                     ddSuppInteract(f,support);
00280                     ddClearLocal(f);
00281                     ddUpdateInteract(table,support);
00282                 }
00283                 f = Cudd_Regular(f->next);
00284             }
00285         }
00286     }
00287     ddClearGlobal(table);
00288 
00289     FREE(support);
00290     return(1);
00291 
00292 } /* end of cuddInitInteract */

void cuddSetInteract ( DdManager *  table,
int  x,
int  y 
)

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

Synopsis [Set interaction matrix entries.]

Description [Given a pair of variables 0 <= x < y < table->size, sets the corresponding bit of the interaction matrix to 1.]

SideEffects [None]

SeeAlso []

Definition at line 152 of file cuddInteract.c.

00156 {
00157     int posn, word, bit;
00158 
00159 #ifdef DD_DEBUG
00160     assert(x < y);
00161     assert(y < table->size);
00162     assert(x >= 0);
00163 #endif
00164 
00165     posn = ((((table->size << 1) - x - 3) * x) >> 1) + y - 1;
00166     word = posn >> LOGBPL;
00167     bit = posn & (BPL-1);
00168     table->interact[word] |= 1L << bit;
00169 
00170 } /* end of cuddSetInteract */

int cuddTestInteract ( DdManager *  table,
int  x,
int  y 
)

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

Synopsis [Test interaction matrix entries.]

Description [Given a pair of variables 0 <= x < y < table->size, tests whether the corresponding bit of the interaction matrix is 1. Returns the value of the bit.]

SideEffects [None]

SeeAlso []

Definition at line 187 of file cuddInteract.c.

00191 {
00192     int posn, word, bit, result;
00193 
00194     if (x > y) {
00195         int tmp = x;
00196         x = y;
00197         y = tmp;
00198     }
00199 #ifdef DD_DEBUG
00200     assert(x < y);
00201     assert(y < table->size);
00202     assert(x >= 0);
00203 #endif
00204 
00205     posn = ((((table->size << 1) - x - 3) * x) >> 1) + y - 1;
00206     word = posn >> LOGBPL;
00207     bit = posn & (BPL-1);
00208     result = (table->interact[word] >> bit) & 1L;
00209     return(result);
00210 
00211 } /* end of cuddTestInteract */

static void ddClearGlobal ( DdManager *  table  )  [static]

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

Synopsis [Scans the DD and clears the LSB of the next pointers.]

Description [The LSB of the next pointers are used as markers to tell whether a node was reached by at least one DFS. Once the interaction matrix is built, these flags are reset.]

SideEffects [None]

SeeAlso []

Definition at line 407 of file cuddInteract.c.

00409 {
00410     int i,j;
00411     DdNode *f;
00412     DdNode *sentinel = &(table->sentinel);
00413     DdNodePtr *nodelist;
00414     int slots;
00415 
00416     for (i = 0; i < table->size; i++) {
00417         nodelist = table->subtables[i].nodelist;
00418         slots = table->subtables[i].slots;
00419         for (j = 0; j < slots; j++) {
00420             f = nodelist[j];
00421             while (f != sentinel) {
00422                 f->next = Cudd_Regular(f->next);
00423                 f = f->next;
00424             }
00425         }
00426     }
00427 
00428 } /* end of ddClearGlobal */

static void ddClearLocal ( DdNode *  f  )  [static]

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

Synopsis [Performs a DFS from f, clearing the LSB of the then pointers.]

Description []

SideEffects [None]

SeeAlso []

Definition at line 344 of file cuddInteract.c.

00346 {
00347     if (cuddIsConstant(f) || !Cudd_IsComplement(cuddT(f))) {
00348         return;
00349     }
00350     /* clear visited flag */
00351     cuddT(f) = Cudd_Regular(cuddT(f));
00352     ddClearLocal(cuddT(f));
00353     ddClearLocal(Cudd_Regular(cuddE(f)));
00354     return;
00355 
00356 } /* end of ddClearLocal */

static void ddSuppInteract ( DdNode *  f,
int *  support 
) [static]

AutomaticStart

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

Synopsis [Find the support of f.]

Description [Performs a DFS from f. Uses the LSB of the then pointer as visited flag.]

SideEffects [Accumulates in support the variables on which f depends.]

SeeAlso []

Definition at line 313 of file cuddInteract.c.

00316 {
00317     if (cuddIsConstant(f) || Cudd_IsComplement(cuddT(f))) {
00318         return;
00319     }
00320 
00321     support[f->index] = 1;
00322     ddSuppInteract(cuddT(f),support);
00323     ddSuppInteract(Cudd_Regular(cuddE(f)),support);
00324     /* mark as visited */
00325     cuddT(f) = Cudd_Complement(cuddT(f));
00326     f->next = Cudd_Complement(f->next);
00327     return;
00328 
00329 } /* end of ddSuppInteract */

static void ddUpdateInteract ( DdManager *  table,
int *  support 
) [static]

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

Synopsis [Marks as interacting all pairs of variables that appear in support.]

Description [If support[i] == support[j] == 1, sets the (i,j) entry of the interaction matrix to 1.]

SideEffects [None]

SeeAlso []

Definition at line 373 of file cuddInteract.c.

00376 {
00377     int i,j;
00378     int n = table->size;
00379 
00380     for (i = 0; i < n-1; i++) {
00381         if (support[i] == 1) {
00382             for (j = i+1; j < n; j++) {
00383                 if (support[j] == 1) {
00384                     cuddSetInteract(table,i,j);
00385                 }
00386             }
00387         }
00388     }
00389 
00390 } /* end of ddUpdateInteract */

Variable Documentation

char rcsid [] DD_UNUSED = "$Id: cuddInteract.c,v 1.12 2004/08/13 18:04:49 fabio Exp $" [static]

Definition at line 107 of file cuddInteract.c.

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