/****************************************************************************
 * NCSA HDF                                                                 *
 * Software Development Group                                               *
 * National Center for Supercomputing Applications                          *
 * University of Illinois at Urbana-Champaign                               *
 * 605 E. Springfield, Champaign IL 61820                                   *
 *                                                                          *
 * For conditions of distribution and use, see the accompanying             *
 * hdf/COPYING file.                                                        *
 *                                                                          *
 ****************************************************************************/

/* $Id$ */

/*-----------------------------------------------------------------------------
 * File:    atom.h
 * Purpose: header file for atom API
 *---------------------------------------------------------------------------*/

/* avoid re-inclusion */
#ifndef __ATOM_H
#define __ATOM_H

#include "H5Aproto.h"   /* Include Public Definitions */

/* Atom Features control */
/* Define the following macro for fast hash calculations (but limited hash sizes) */
#define HASH_SIZE_POWER_2

/* Define the following macro for atom caching over all the atoms */
#define ATOMS_ARE_CACHED

#if defined HDF5_ATOM_MASTER | defined HDF5_ATOM_TESTER
#ifdef ATOMS_ARE_CACHED
/* # of previous atoms cached */
#define ATOM_CACHE_SIZE 4
#endif /* ATOMS_ARE_CACHED */

/* Map an atom to a Group number */
#define ATOM_TO_GROUP(a)    ((group_t)((((hatom_t)(a))>>((sizeof(hatom_t)*8)-GROUP_BITS))&GROUP_MASK))

#ifdef HASH_SIZE_POWER_2
/* Map an atom to a hash location (assumes s is a power of 2 and smaller than the ATOM_MASK constant) */
#define ATOM_TO_LOC(a,s)    ((hatom_t)(a)&((s)-1))
#else /* HASH_SIZE_POWER_2 */
/* Map an atom to a hash location */
#define ATOM_TO_LOC(a,s)    (((hatom_t)(a)&ATOM_MASK)%(s))
#endif /* HASH_SIZE_POWER_2 */

/* Atom information structure used */
typedef struct atom_info_struct_tag {
    hatom_t id;              /* atom ID for this info */
    VOIDP *obj_ptr;         /* pointer associated with the atom */
    struct atom_info_struct_tag *next;   /* link to next atom (in case of hash-clash) */
  }atom_info_t;

/* Atom group structure used */
typedef struct atom_group_struct_tag {
    uintn count;            /* # of times this group has been initialized */
    uintn reserved;         /* # of atoms to reserve for constant atoms */
    uintn wrapped;          /* whether the id count has wrapped around */
    intn hash_size;         /* size of the hash table to store the atoms in */
    uintn atoms;            /* current number of atoms held */
    uintn nextid;           /* atom ID to use for the next atom */
    atom_info_t **atom_list;/* pointer to an array of ptrs to atoms */
  }atom_group_t;

/* Define this in only one place */
#ifdef HDF5_ATOM_MASTER

/* Array of pointers to atomic groups */
static atom_group_t *atom_group_list[MAXGROUP]={NULL};

/* Pointer to the atom node free list */
static atom_info_t *atom_free_list=NULL;

#ifdef ATOMS_ARE_CACHED
/* Array of pointers to atomic groups */
static hatom_t atom_id_cache[ATOM_CACHE_SIZE]={-1,-1,-1,-1};
static VOIDP atom_obj_cache[ATOM_CACHE_SIZE]={NULL};
#endif /* ATOMS_ARE_CACHED */

#endif /* HDF5_ATOM_MASTER */

/* Useful routines for generally private use */

#endif /* HDF5_ATOM_MASTER | HDF5_ATOM_TESTER */

#endif /* __ATOM_H */