Functions for symmetry-based variable reordering. More...

#include "util.h"
#include "cuddInt.h"

Include dependency graph for cuddSymmetry.c:

Macros
#define	MV_OOM (Move *)1

Functions
void	Cudd_SymmProfile (DdManager *table, int lower, int upper)
	Prints statistics on symmetric variables. More...

int	cuddSymmCheck (DdManager *table, int x, int y)
	Checks for symmetry of x and y. More...

int	cuddSymmSifting (DdManager *table, int lower, int upper)
	Symmetric sifting algorithm. More...

int	cuddSymmSiftingConv (DdManager *table, int lower, int upper)
	Symmetric sifting to convergence algorithm. More...

static int	ddSymmUniqueCompare (void const ptrX, void const ptrY)
	Comparison function used by qsort. More...

static int	ddSymmSiftingAux (DdManager *table, int x, int xLow, int xHigh)
	Given xLow <= x <= xHigh moves x up and down between the boundaries. More...

static int	ddSymmSiftingConvAux (DdManager *table, int x, int xLow, int xHigh)
	Given xLow <= x <= xHigh moves x up and down between the boundaries. More...

static Move *	ddSymmSiftingUp (DdManager *table, int y, int xLow)
	Moves x up until either it reaches the bound (xLow) or the size of the DD heap increases too much. More...

static Move *	ddSymmSiftingDown (DdManager *table, int x, int xHigh)
	Moves x down until either it reaches the bound (xHigh) or the size of the DD heap increases too much. More...

static int	ddSymmGroupMove (DdManager table, int x, int y, Move *moves)
	Swaps two groups. More...

static int	ddSymmGroupMoveBackward (DdManager *table, int x, int y)
	Undoes the swap of two groups. More...

static int	ddSymmSiftingBackward (DdManager table, Move moves, int size)
	Given a set of moves, returns the DD heap to the position giving the minimum size. More...

static void	ddSymmSummary (DdManager table, int lower, int upper, int symvars, int *symgroups)
	Counts numbers of symmetric variables and symmetry groups. More...

Detailed Description

Functions for symmetry-based variable reordering.

Author: Shipra Panda, Fabio Somenzi

Copyright

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.

Function Documentation

◆ Cudd_SymmProfile()

void Cudd_SymmProfile	(	DdManager *	table,
		int	lower,
		int	upper
	)

Prints statistics on symmetric variables.

The information is accurate only if this function is called right after reordering with methods CUDD_REORDER_SYMM_SIFT or CUDD_REORDER_SYMM_SIFT_CONV.

Side effects None

◆ cuddSymmCheck()

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

Checks for symmetry of x and y.

Ignores projection functions, unless they are isolated.

Returns: 1 in case of symmetry; 0 otherwise.

Side effects None

◆ cuddSymmSifting()

int cuddSymmSifting	(	DdManager *	table,
		int	lower,
		int	upper
	)

Symmetric sifting algorithm.

Assumes that no dead nodes are present.

Order all the variables according to the number of entries in each unique subtable.
Sift the variable up and down, remembering each time the total size of the DD heap and grouping variables that are symmetric.
Select the best permutation.
Repeat 3 and 4 for all variables.

Returns: 1 plus the number of symmetric variables if successful; 0 otherwise.

Side effects None

See also: cuddSymmSiftingConv

◆ cuddSymmSiftingConv()

int cuddSymmSiftingConv	(	DdManager *	table,
		int	lower,
		int	upper
	)

Symmetric sifting to convergence algorithm.

Assumes that no dead nodes are present.

Order all the variables according to the number of entries in each unique subtable.
Sift the variable up and down, remembering each time the total size of the DD heap and grouping variables that are symmetric.
Select the best permutation.
Repeat 3 and 4 for all variables.
Repeat 1-4 until no further improvement.

Returns: 1 plus the number of symmetric variables if successful; 0 otherwise.

Side effects None

See also: cuddSymmSifting

◆ ddSymmGroupMove()

static int ddSymmGroupMove	(	DdManager *	table,
		int	x,
		int	y,
		Move **	moves
	)

static

Swaps two groups.

x is assumed to be the bottom variable of the first group. y is assumed to be the top variable of the second group. Updates the list of moves.

Returns: the number of keys in the table if successful; 0 otherwise.

Side effects None

◆ ddSymmGroupMoveBackward()

static int ddSymmGroupMoveBackward	(	DdManager *	table,
		int	x,
		int	y
	)

static

Undoes the swap of two groups.

x is assumed to be the bottom variable of the first group. y is assumed to be the top variable of the second group.

Returns: the number of keys in the table if successful; 0 otherwise.

Side effects None

◆ ddSymmSiftingAux()

static int ddSymmSiftingAux	(	DdManager *	table,
		int	x,
		int	xLow,
		int	xHigh
	)

static

Given xLow <= x <= xHigh moves x up and down between the boundaries.

Finds the best position and does the required changes. Assumes that x is not part of a symmetry group.

Returns: 1 if successful; 0 otherwise.

Side effects None

◆ ddSymmSiftingBackward()

static int ddSymmSiftingBackward	(	DdManager *	table,
		Move *	moves,
		int	size
	)

static

Given a set of moves, returns the DD heap to the position giving the minimum size.

In case of ties, returns to the closest position giving the minimum size.

Returns: 1 in case of success; 0 otherwise.

Side effects None

◆ ddSymmSiftingConvAux()

static int ddSymmSiftingConvAux	(	DdManager *	table,
		int	x,
		int	xLow,
		int	xHigh
	)

static

Given xLow <= x <= xHigh moves x up and down between the boundaries.

Finds the best position and does the required changes. Assumes that x is either an isolated variable, or it is the bottom of a symmetry group. All symmetries may not have been found, because of exceeded growth limit.

Returns: 1 if successful; 0 otherwise.

Side effects None

◆ ddSymmSiftingDown()

static Move* ddSymmSiftingDown	(	DdManager *	table,
		int	x,
		int	xHigh
	)

static

Moves x down until either it reaches the bound (xHigh) or the size of the DD heap increases too much.

Assumes that x is the bottom of a symmetry group. Checks x for symmetry to the adjacent variables. If symmetry is found, the symmetry group of x is merged with the symmetry group of the other variable.

Returns: the set of moves in case of success; MV_OOM if memory is full.

Side effects None

◆ ddSymmSiftingUp()

static Move* ddSymmSiftingUp	(	DdManager *	table,
		int	y,
		int	xLow
	)

static

Moves x up until either it reaches the bound (xLow) or the size of the DD heap increases too much.

Assumes that x is the top of a symmetry group. Checks x for symmetry to the adjacent variables. If symmetry is found, the symmetry group of x is merged with the symmetry group of the other variable.

Returns: the set of moves in case of success; MV_OOM if memory is full.

Side effects None

◆ ddSymmSummary()

static void ddSymmSummary	(	DdManager *	table,
		int	lower,
		int	upper,
		int *	symvars,
		int *	symgroups
	)

static

Counts numbers of symmetric variables and symmetry groups.

Side effects None

◆ ddSymmUniqueCompare()

static int ddSymmUniqueCompare	(	void const *	ptrX,
		void const *	ptrY
	)

static

Comparison function used by qsort.

Used to order the variables according to the number of keys in the subtables.

Returns: the difference in number of keys between the two variables being compared.

Side effects None

Macros

Functions

Detailed Description

Function Documentation

◆ Cudd_SymmProfile()

◆ cuddSymmCheck()

◆ cuddSymmSifting()

◆ cuddSymmSiftingConv()

◆ ddSymmGroupMove()

◆ ddSymmGroupMoveBackward()

◆ ddSymmSiftingAux()

◆ ddSymmSiftingBackward()

◆ ddSymmSiftingConvAux()

◆ ddSymmSiftingDown()

◆ ddSymmSiftingUp()

◆ ddSymmSummary()

◆ ddSymmUniqueCompare()