#include "CUDD/util.h"
#include "CUDD/cuddInt.h"

Macros
#define	BPL 32

#define	LOGBPL 5

Functions
static void	ddSuppInteract (DdNode f, char support)

static void	ddClearLocal (DdNode *f)

static void	ddUpdateInteract (DdManager table, char 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 1.14 2012/02/05 01:07:19 fabio Exp $"

Macro Definition Documentation

◆ BPL

#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 interact, but that for a given variable order have no arc connecting their layers when they are adjacent. For instance, in ite(a,b,c) with the order a<b<c, b and c interact, but are not connected.]

SeeAlso []

Author [Fabio Somenzi]

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 89 of file cuddInteract.c.

◆ LOGBPL

#define LOGBPL 5

Definition at line 90 of file cuddInteract.c.

Function Documentation

◆ cuddInitInteract()

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 234 of file cuddInteract.c.

 {
     int i,j;
     unsigned long words;
     long *interact;
     char *support;
     DdNode *f;
     DdNode *sentinel = &(table->sentinel);
     DdNodePtr *nodelist;
     int slots;
     unsigned long n = (unsigned long) table->size;
 
     words = ((n * (n-1)) >> (1 + LOGBPL)) + 1;
     table->interact = interact = ALLOC(long,words);
     if (interact == NULL) {
     table->errorCode = CUDD_MEMORY_OUT;
     return(0);
     }
     for (i = 0; i < words; i++) {
     interact[i] = 0;
     }
 
     support = ALLOC(char,n);
     if (support == NULL) {
     table->errorCode = CUDD_MEMORY_OUT;
     FREE(interact);
     return(0);
     }
     for (i = 0; i < n; i++) {
         support[i] = 0;
     }
 
     for (i = 0; i < n; i++) {
     nodelist = table->subtables[i].nodelist;
     slots = table->subtables[i].slots;
     for (j = 0; j < slots; j++) {
         f = nodelist[j];
         while (f != sentinel) {
         /* A node is a root of the DAG if it cannot be
         ** reached by nodes above it. If a node was never
         ** reached during the previous depth-first searches,
         ** then it is a root, and we start a new depth-first
         ** search from it.
         */
         if (!Cudd_IsComplement(f->next)) {
             ddSuppInteract(f,support);
             ddClearLocal(f);
             ddUpdateInteract(table,support);
         }
         f = Cudd_Regular(f->next);
         }
     }
     }
     ddClearGlobal(table);
 
     FREE(support);
     return(1);
 
 } /* end of cuddInitInteract */

◆ cuddSetInteract()

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 153 of file cuddInteract.c.

 {
     int posn, word, bit;
 
 #ifdef DD_DEBUG
     assert(x < y);
     assert(y < table->size);
     assert(x >= 0);
 #endif
 
     posn = ((((table->size << 1) - x - 3) * x) >> 1) + y - 1;
     word = posn >> LOGBPL;
     bit = posn & (BPL-1);
     table->interact[word] |= 1L << bit;
 
 } /* end of cuddSetInteract */

◆ cuddTestInteract()

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 188 of file cuddInteract.c.

 {
     int posn, word, bit, result;
 
     if (x > y) {
     int tmp = x;
     x = y;
     y = tmp;
     }
 #ifdef DD_DEBUG
     assert(x < y);
     assert(y < table->size);
     assert(x >= 0);
 #endif
 
     posn = ((((table->size << 1) - x - 3) * x) >> 1) + y - 1;
     word = posn >> LOGBPL;
     bit = posn & (BPL-1);
     result = (table->interact[word] >> bit) & 1L;
     return(result);
 
 } /* end of cuddTestInteract */

◆ ddClearGlobal()

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 410 of file cuddInteract.c.

 {
     int i,j;
     DdNode *f;
     DdNode *sentinel = &(table->sentinel);
     DdNodePtr *nodelist;
     int slots;
 
     for (i = 0; i < table->size; i++) {
     nodelist = table->subtables[i].nodelist;
     slots = table->subtables[i].slots;
     for (j = 0; j < slots; j++) {
         f = nodelist[j];
         while (f != sentinel) {
         f->next = Cudd_Regular(f->next);
         f = f->next;
         }
     }
     }
 
 } /* end of ddClearGlobal */

◆ ddClearLocal()

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 345 of file cuddInteract.c.

 {
     if (cuddIsConstant(f) || !Cudd_IsComplement(cuddT(f))) {
     return;
     }
     /* clear visited flag */
     cuddT(f) = Cudd_Regular(cuddT(f));
     ddClearLocal(cuddT(f));
     ddClearLocal(Cudd_Regular(cuddE(f)));
     return;
 
 } /* end of ddClearLocal */

◆ ddSuppInteract()

static void ddSuppInteract	(	DdNode *	f,
		char *	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 314 of file cuddInteract.c.

 {
     if (cuddIsConstant(f) || Cudd_IsComplement(cuddT(f))) {
     return;
     }
 
     support[f->index] = 1;
     ddSuppInteract(cuddT(f),support);
     ddSuppInteract(Cudd_Regular(cuddE(f)),support);
     /* mark as visited */
     cuddT(f) = Cudd_Complement(cuddT(f));
     f->next = Cudd_Complement(f->next);
     return;
 
 } /* end of ddSuppInteract */

◆ ddUpdateInteract()

static void ddUpdateInteract	(	DdManager *	table,
		char *	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 [Clears support.]

SeeAlso []

Definition at line 374 of file cuddInteract.c.

 {
     int i,j;
     int n = table->size;
 
     for (i = 0; i < n-1; i++) {
     if (support[i] == 1) {
             support[i] = 0;
         for (j = i+1; j < n; j++) {
         if (support[j] == 1) {
             cuddSetInteract(table,i,j);
         }
         }
     }
     }
     support[n-1] = 0;
 
 } /* end of ddUpdateInteract */

Variable Documentation

◆ DD_UNUSED

char rcsid [] DD_UNUSED = "$Id: cuddInteract.c,v 1.14 2012/02/05 01:07:19 fabio Exp $"

static

Definition at line 108 of file cuddInteract.c.

Macros

Functions

Variables

Macro Definition Documentation

◆ BPL

◆ LOGBPL

Function Documentation

◆ cuddInitInteract()

◆ cuddSetInteract()

◆ cuddTestInteract()

◆ ddClearGlobal()

◆ ddClearLocal()

◆ ddSuppInteract()

◆ ddUpdateInteract()

Variable Documentation

◆ DD_UNUSED