src/bdd/cudd/cuddLevelQ.c File Reference

#include "util_hack.h"
#include "cuddInt.h"

Include dependency graph for cuddLevelQ.c:

Go to the source code of this file.

Defines
#define	lqHash(key, shift)   (((unsigned)(key) * DD_P1) >> (shift))
Functions
static DdQueueItem *hashLookup	ARGS ((DdLevelQueue *queue, void *key))
static int hashInsert	ARGS ((DdLevelQueue *queue, DdQueueItem *item))
static int hashResize	ARGS ((DdLevelQueue *queue))
DdLevelQueue *	cuddLevelQueueInit (int levels, int itemSize, int numBuckets)
void	cuddLevelQueueQuit (DdLevelQueue *queue)
void *	cuddLevelQueueEnqueue (DdLevelQueue *queue, void *key, int level)
void	cuddLevelQueueDequeue (DdLevelQueue *queue, int level)
static DdQueueItem *	hashLookup (DdLevelQueue *queue, void *key)
static int	hashInsert (DdLevelQueue *queue, DdQueueItem *item)
static void	hashDelete (DdLevelQueue *queue, DdQueueItem *item)
static int	hashResize (DdLevelQueue *queue)
Variables
static char rcsid[]	DD_UNUSED = "$Id: cuddLevelQ.c,v 1.1.1.1 2003/02/24 22:23:52 wjiang Exp $"

---

Define Documentation

#define lqHash	(	key,
		shift		)	(((unsigned)(key) * DD_P1) >> (shift))

Macro***********************************************************************

Synopsis [Hash function for the table of a level queue.]

Description [Hash function for the table of a level queue.]

SideEffects [None]

SeeAlso [hashInsert hashLookup hashDelete]

Definition at line 97 of file cuddLevelQ.c.

---

Function Documentation

static int hashResize ARGS

(

(DdLevelQueue *queue)

)

[static]

static void hashDelete ARGS

(

(DdLevelQueue *queue, DdQueueItem *item)

)

[static]

static DdQueueItem* hashLookup ARGS

(

(DdLevelQueue *queue, void *key)

)

[static]

AutomaticStart

void cuddLevelQueueDequeue	(	DdLevelQueue *	queue,
		int	level
	)

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

Synopsis [Remove an item from the front of a level queue.]

Description [Remove an item from the front of a level queue.]

SideEffects [None]

SeeAlso [cuddLevelQueueEnqueue]

Definition at line 323 of file cuddLevelQ.c.

{
    DdQueueItem *item = (DdQueueItem *) queue->first;

    /* Delete from the hash table. */
    hashDelete(queue,item);

    /* Since we delete from the front, if this is the last item for
    ** its level, there are no other items for the same level. */
    if (queue->last[level] == item)
        queue->last[level] = NULL;

    queue->first = item->next;
    /* Put item on the free list. */
    item->next = queue->freelist;
    queue->freelist = item;
    /* Update stats. */
    queue->size--;
    return;

} /* end of cuddLevelQueueDequeue */

void* cuddLevelQueueEnqueue	(	DdLevelQueue *	queue,
		void *	key,
		int	level
	)

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

Synopsis [Inserts a new key in a level queue.]

Description [Inserts a new key in a level queue. A new entry is created in the queue only if the node is not already enqueued. Returns a pointer to the queue item if successful; NULL otherwise.]

SideEffects [None]

SeeAlso [cuddLevelQueueInit cuddLevelQueueDequeue]

Definition at line 251 of file cuddLevelQ.c.

{
    int plevel;
    DdQueueItem *item;

#ifdef DD_DEBUG
    assert(level < queue->levels);
#endif
    /* Check whether entry for this node exists. */
    item = hashLookup(queue,key);
    if (item != NULL) return(item);

    /* Get a free item from either the free list or the memory manager. */
    if (queue->freelist == NULL) {
        item = (DdQueueItem *) ALLOC(char, queue->itemsize);
        if (item == NULL)
            return(NULL);
    } else {
        item = queue->freelist;
        queue->freelist = item->next;
    }
    /* Initialize. */
    memset(item, 0, queue->itemsize);
    item->key = key;
    /* Update stats. */
    queue->size++;

    if (queue->last[level]) {
        /* There are already items for this level in the queue. */
        item->next = queue->last[level]->next;
        queue->last[level]->next = item;
    } else {
        /* There are no items at the current level.  Look for the first
        ** non-empty level preceeding this one. */
        plevel = level;
        while (plevel != 0 && queue->last[plevel] == NULL)
            plevel--;
        if (queue->last[plevel] == NULL) {
            /* No element precedes this one in the queue. */
            item->next = (DdQueueItem *) queue->first;
            queue->first = item;
        } else {
            item->next = queue->last[plevel]->next;
            queue->last[plevel]->next = item;
        }
    }
    queue->last[level] = item;

    /* Insert entry for the key in the hash table. */
    if (hashInsert(queue,item) == 0) {
        return(NULL);
    }
    return(item);

} /* end of cuddLevelQueueEnqueue */

DdLevelQueue* cuddLevelQueueInit	(	int	levels,
		int	itemSize,
		int	numBuckets
	)

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

Synopsis [Initializes a level queue.]

Description [Initializes a level queue. A level queue is a queue where inserts are based on the levels of the nodes. Within each level the policy is FIFO. Level queues are useful in traversing a BDD top-down. Queue items are kept in a free list when dequeued for efficiency. Returns a pointer to the new queue if successful; NULL otherwise.]

SideEffects [None]

SeeAlso [cuddLevelQueueQuit cuddLevelQueueEnqueue cuddLevelQueueDequeue]

Definition at line 138 of file cuddLevelQ.c.

{
    DdLevelQueue *queue;
    int logSize;

    queue = ALLOC(DdLevelQueue,1);
    if (queue == NULL)
        return(NULL);
#ifdef __osf__
#pragma pointer_size save
#pragma pointer_size short
#endif
    /* Keep pointers to the insertion points for all levels. */
    queue->last = ALLOC(DdQueueItem *, levels);
#ifdef __osf__
#pragma pointer_size restore
#endif
    if (queue->last == NULL) {
        FREE(queue);
        return(NULL);
    }
    /* Use a hash table to test for uniqueness. */
    if (numBuckets < 2) numBuckets = 2;
    logSize = cuddComputeFloorLog2(numBuckets);
    queue->numBuckets = 1 << logSize;
    queue->shift = sizeof(int) * 8 - logSize;
#ifdef __osf__
#pragma pointer_size save
#pragma pointer_size short
#endif
    queue->buckets = ALLOC(DdQueueItem *, queue->numBuckets);
#ifdef __osf__
#pragma pointer_size restore
#endif
    if (queue->buckets == NULL) {
        FREE(queue->last);
        FREE(queue);
        return(NULL);
    }
#ifdef __osf__
#pragma pointer_size save
#pragma pointer_size short
#endif
    memset(queue->last, 0, levels * sizeof(DdQueueItem *));
    memset(queue->buckets, 0, queue->numBuckets * sizeof(DdQueueItem *));
#ifdef __osf__
#pragma pointer_size restore
#endif
    queue->first = NULL;
    queue->freelist = NULL;
    queue->levels = levels;
    queue->itemsize = itemSize;
    queue->size = 0;
    queue->maxsize = queue->numBuckets * DD_MAX_SUBTABLE_DENSITY;
    return(queue);

} /* end of cuddLevelQueueInit */

void cuddLevelQueueQuit

(

DdLevelQueue *

queue

)

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

Synopsis [Shuts down a level queue.]

Description [Shuts down a level queue and releases all the associated memory.]

SideEffects [None]

SeeAlso [cuddLevelQueueInit]

Definition at line 213 of file cuddLevelQ.c.

{
    DdQueueItem *item;

    while (queue->freelist != NULL) {
        item = queue->freelist;
        queue->freelist = item->next;
        FREE(item);
    }
    while (queue->first != NULL) {
        item = (DdQueueItem *) queue->first;
        queue->first = item->next;
        FREE(item);
    }
    FREE(queue->buckets);
    FREE(queue->last);
    FREE(queue);
    return;

} /* end of cuddLevelQueueQuit */

static void hashDelete	(	DdLevelQueue *	queue,
		DdQueueItem *	item
	)			[static]

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

Synopsis [Removes an item from the hash table of a level queue.]

Description [Removes an item from the hash table of a level queue. Nothing is done if the item is not in the table.]

SideEffects [None]

SeeAlso [cuddLevelQueueDequeue hashInsert]

Definition at line 436 of file cuddLevelQ.c.

{
    int posn;
    DdQueueItem *prevItem;

    posn = lqHash(item->key,queue->shift);
    prevItem = queue->buckets[posn];

    if (prevItem == NULL) return;
    if (prevItem == item) {
        queue->buckets[posn] = prevItem->cnext;
        return;
    }

    while (prevItem->cnext != NULL) {
        if (prevItem->cnext == item) {
            prevItem->cnext = item->cnext;
            return;
        }
        prevItem = prevItem->cnext;
    }
    return;

} /* end of hashDelete */

static int hashInsert	(	DdLevelQueue *	queue,
		DdQueueItem *	item
	)			[static]

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

Synopsis [Inserts an item in the hash table of a level queue.]

Description [Inserts an item in the hash table of a level queue. Returns 1 if successful; 0 otherwise. No check is performed to see if an item with the same key is already in the hash table.]

SideEffects [None]

SeeAlso [cuddLevelQueueEnqueue]

Definition at line 402 of file cuddLevelQ.c.

{
    int result;
    int posn;

    if (queue->size > queue->maxsize) {
        result = hashResize(queue);
        if (result == 0) return(0);
    }

    posn = lqHash(item->key,queue->shift);
    item->cnext = queue->buckets[posn];
    queue->buckets[posn] = item;

    return(1);
    
} /* end of hashInsert */

static DdQueueItem* hashLookup	(	DdLevelQueue *	queue,
		void *	key
	)			[static]

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

Synopsis [Looks up a key in the hash table of a level queue.]

Description [Looks up a key in the hash table of a level queue. Returns a pointer to the item with the given key if the key is found; NULL otherwise.]

SideEffects [None]

SeeAlso [cuddLevelQueueEnqueue hashInsert]

Definition at line 367 of file cuddLevelQ.c.

{
    int posn;
    DdQueueItem *item;

    posn = lqHash(key,queue->shift);
    item = queue->buckets[posn];

    while (item != NULL) {
        if (item->key == key) {
            return(item);
        }
        item = item->cnext;
    }
    return(NULL);

} /* end of hashLookup */

static int hashResize

(

DdLevelQueue *

queue

)

[static]

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

Synopsis [Resizes the hash table of a level queue.]

Description [Resizes the hash table of a level queue. Returns 1 if successful; 0 otherwise.]

SideEffects [None]

SeeAlso [hashInsert]

Definition at line 477 of file cuddLevelQ.c.

{
    int j;
    int posn;
    DdQueueItem *item;
    DdQueueItem *next;
    int numBuckets;
#ifdef __osf__
#pragma pointer_size save
#pragma pointer_size short
#endif
    DdQueueItem **buckets;
    DdQueueItem **oldBuckets = queue->buckets;
#ifdef __osf__
#pragma pointer_size restore
#endif
    int shift;
    int oldNumBuckets = queue->numBuckets;
    extern void (*MMoutOfMemory)(long);
    void (*saveHandler)(long);

    /* Compute the new size of the subtable. */
    numBuckets = oldNumBuckets << 1;
    saveHandler = MMoutOfMemory;
    MMoutOfMemory = Cudd_OutOfMem;
#ifdef __osf__
#pragma pointer_size save
#pragma pointer_size short
#endif
    buckets = queue->buckets = ALLOC(DdQueueItem *, numBuckets);
    if (buckets == NULL) {
        queue->maxsize <<= 1;
        return(1);
    }

    queue->numBuckets = numBuckets;
    shift = --(queue->shift);
    queue->maxsize <<= 1;
    memset(buckets, 0, numBuckets * sizeof(DdQueueItem *));
#ifdef __osf__
#pragma pointer_size restore
#endif
    for (j = 0; j < oldNumBuckets; j++) {
        item = oldBuckets[j];
        while (item != NULL) {
            next = item->cnext;
            posn = lqHash(item->key, shift);
            item->cnext = buckets[posn];
            buckets[posn] = item;
            item = next;
        }
    }
    FREE(oldBuckets);
    return(1);

} /* end of hashResize */

---

Variable Documentation

char rcsid [] DD_UNUSED = "$Id: cuddLevelQ.c,v 1.1.1.1 2003/02/24 22:23:52 wjiang Exp $" [static]

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

FileName [cuddLevelQ.c]

PackageName [cudd]

Synopsis [Procedure to manage level queues.]

Description [The functions in this file allow an application to easily manipulate a queue where nodes are prioritized by level. The emphasis is on efficiency. Therefore, the queue items can have variable size. If the application does not need to attach information to the nodes, it can declare the queue items to be of type DdQueueItem. Otherwise, it can declare them to be of a structure type such that the first three fields are data pointers. The third pointer points to the node. The first two pointers are used by the level queue functions. The remaining fields are initialized to 0 when a new item is created, and are then left to the exclusive use of the application. On the DEC Alphas the three pointers must be 32-bit pointers when CUDD is compiled with 32-bit pointers. The level queue functions make sure that each node appears at most once in the queue. They do so by keeping a hash table where the node is used as key. Queue items are recycled via a free list for efficiency.

Internal procedures provided by this module:

• cuddLevelQueueInit()
• cuddLevelQueueQuit()
• cuddLevelQueueEnqueue()
• cuddLevelQueueDequeue()

Static procedures included in this module:

• hashLookup()
• hashInsert()
• hashDelete()
• hashResize()

]

SeeAlso []

Author [Fabio Somenzi]

Copyright [This file was created at the University of Colorado at Boulder. The University of Colorado at Boulder makes no warranty about the suitability of this software for any purpose. It is presented on an AS IS basis.]

Definition at line 74 of file cuddLevelQ.c.