cuddSplit.c File Reference

Returns a subset of minterms from a boolean function. More...

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

Include dependency graph for cuddSplit.c:

Functions
DdNode *	Cudd_SplitSet (DdManager *manager, DdNode *S, DdNode **xVars, int n, double m)
	Returns m minterms from a BDD. More...
DdNode *	cuddSplitSetRecur (DdManager *manager, st_table *mtable, int *varSeen, DdNode *p, double n, double max, int index)
	Implements the recursive step of Cudd_SplitSet. More...
static DdNode *	selectMintermsFromUniverse (DdManager *manager, int *varSeen, double n)
	This function prepares an array of variables which have not been encountered so far when traversing the procedure cuddSplitSetRecur. More...
static DdNode *	mintermsFromUniverse (DdManager *manager, DdNode **vars, int numVars, double n, int index)
	Recursive procedure to extract n mintems from constant 1. More...
static double	bddAnnotateMintermCount (DdManager *manager, DdNode *node, double max, st_table *table)
	Annotates every node in the BDD node with its minterm count. More...

Detailed Description

Returns a subset of minterms from a boolean function.

Author

Balakrishna Kumthekar

Copyright

Copyright (c) 1995-2015, 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:

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Function Documentation

bddAnnotateMintermCount()

static double bddAnnotateMintermCount ( DdManager *  manager, DdNode *  node, double  max, st_table *  table  )

static

Annotates every node in the BDD node with its minterm count.

In this function, every node and the minterm count represented by it are stored in a hash table.

Side effects Fills up 'table' with the pair <node,minterm_count>.

Cudd_SplitSet()

DdNode* Cudd_SplitSet	(	DdManager *	manager,
		DdNode *	S,
		DdNode **	xVars,
		int	n,
		double	m
	)

Returns m minterms from a BDD.

Returns m minterms from a BDD whose support has n variables at most. The procedure tries to create as few extra nodes as possible. The function represented by S depends on at most n of the variables in xVars.

Returns

a BDD with m minterms of the on-set of S if successful; NULL otherwise.

Side effects None

cuddSplitSetRecur()

DdNode* cuddSplitSetRecur	(	DdManager *	manager,
		st_table *	mtable,
		int *	varSeen,
		DdNode *	p,
		double	n,
		double	max,
		int	index
	)

Implements the recursive step of Cudd_SplitSet.

The procedure recursively traverses the BDD and checks to see if any node satisfies the minterm requirements as specified by 'n'. At any node X, n is compared to the number of minterms in the onset of X's children. If either of the child nodes have exactly n minterms, then that node is returned; else, if n is greater than the onset of one of the child nodes, that node is retained and the difference in the number of minterms is extracted from the other child. In case n minterms can be extracted from constant 1, the algorithm returns the result with at most log(n) nodes.

Side effects The array 'varSeen' is updated at every recursive call

to set the variables traversed by the procedure.

mintermsFromUniverse()

static DdNode* mintermsFromUniverse ( DdManager *  manager, DdNode **  vars, int  numVars, double  n, int  index  )

static

Recursive procedure to extract n mintems from constant 1.

Side effects None

selectMintermsFromUniverse()

static DdNode* selectMintermsFromUniverse ( DdManager *  manager, int *  varSeen, double  n  )

static

This function prepares an array of variables which have not been encountered so far when traversing the procedure cuddSplitSetRecur.

This array is then used to extract the required number of minterms from a constant 1. The algorithm guarantees that the size of BDD will be at most log(n).

Side effects None