/****************************************************************************
 * 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 _H5Aprivate_H
#define _H5Aprivate_H
#include <H5Apublic.h>   /* Include Public Definitions */

/* Private headers needed by this file */
#include <H5private.h>

/* 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

#ifdef ATOMS_ARE_CACHED
#  define ATOM_CACHE_SIZE 4	/* # of previous atoms cached */
#endif

/* Map an atom to a Group number */
#define ATOM_TO_GROUP(a)    ((group_t)((((hid_t)(a))>>((sizeof(hid_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)    ((hid_t)(a)&((s)-1))
#else
/*
 * Map an atom to a hash location.
 */
#  define ATOM_TO_LOC(a,s)    (((hid_t)(a)&ATOM_MASK)%(s))
#endif

/* Default sizes of the hash-tables for various atom groups */
#define H5A_ERRSTACK_HASHSIZE  	64
#define H5A_FILEID_HASHSIZE    	64
#define H5A_TEMPID_HASHSIZE    	64
#define H5A_DATATYPEID_HASHSIZE	64
#define H5A_DATASPACEID_HASHSIZE 64
#define H5A_DATASETID_HASHSIZE	64
#define H5A_OID_HASHSIZE	    64

/* Atom information structure used */
typedef struct atom_info_struct_tag {
    hid_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;


#endif