cuddlevelq.c

主要进行大规模的电路综合

/**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:
                <ul>
		<li> cuddLevelQueueInit()
		<li> cuddLevelQueueQuit()
		<li> cuddLevelQueueEnqueue()
		<li> cuddLevelQueueDequeue()
		</ul>
  Static procedures included in this module:
		<ul>
		<li> hashLookup()
		<li> hashInsert()
		<li> hashDelete()
		<li> hashResize()
		</ul>
		]

  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.]

******************************************************************************/

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

/*---------------------------------------------------------------------------*/
/* Constant declarations                                                     */
/*---------------------------------------------------------------------------*/


/*---------------------------------------------------------------------------*/
/* Stucture declarations                                                     */
/*---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------*/
/* Type declarations                                                         */
/*---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------*/
/* Variable declarations                                                     */
/*---------------------------------------------------------------------------*/

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

/*---------------------------------------------------------------------------*/
/* Macro declarations                                                        */
/*---------------------------------------------------------------------------*/


/**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]

******************************************************************************/
#if SIZEOF_VOID_P == 8 && SIZEOF_INT == 4
#define lqHash(key,shift) \
(((unsigned)(unsigned long)(key) * DD_P1) >> (shift))
#else
#define lqHash(key,shift) \
(((unsigned)(key) * DD_P1) >> (shift))
#endif


/**AutomaticStart*************************************************************/

/*---------------------------------------------------------------------------*/
/* Static function prototypes                                                */
/*---------------------------------------------------------------------------*/

static DdQueueItem * hashLookup ARGS((DdLevelQueue *queue, void *key));
static int hashInsert ARGS((DdLevelQueue *queue, DdQueueItem *item));
static void hashDelete ARGS((DdLevelQueue *queue, DdQueueItem *item));
static int hashResize ARGS((DdLevelQueue *queue));

/**AutomaticEnd***************************************************************/


/*---------------------------------------------------------------------------*/
/* Definition of internal functions                                          */
/*---------------------------------------------------------------------------*/


/**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]

******************************************************************************/
DdLevelQueue *
cuddLevelQueueInit(
  int  levels /* number of levels */,
  int  itemSize /* size of the item */,
  int  numBuckets /* initial number of hash buckets */)
{
    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 */


/**Function********************************************************************

  Synopsis    [Shuts down a level queue.]

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

  SideEffects [None]

  SeeAlso     [cuddLevelQueueInit]

******************************************************************************/
void
cuddLevelQueueQuit(
  DdLevelQueue * queue)
{
    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 */


/**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]

******************************************************************************/
void *
cuddLevelQueueEnqueue(
  DdLevelQueue * queue /* level queue */,
  void * key /* key to be enqueued */,
  int  level /* level at which to insert */)
{
    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) {