ident.c

/*
    ident.c - routines to associate an identifier with an object
 
    UltraRogue: The Ultimate Adventure in the Dungeons of Doom
    Copyright (C) 1986, 1991, 1993, 1995 Herb Chong
    All rights reserved.

    See the file LICENSE.TXT for full copyright and licensing information.
*/

/*
 * ident
 *
 * This file contains routines to associate an identifier with an object. The
 * identifiers are organized by type. Once an identifier is attached to an
 * object, it remains with that object until the object is removed from the
 * game. The identifiers are small integers, and they are assigned merely by
 * counting objects of the same type. Allocation picks the next available
 * integer.
 *
 * It is required that the linked list be sorted within types so that gaps can
 * easily be detected.
 */

#include "rogue.h"

/*
 * Index of 0 is invalid (unused state)
 */

char print_letters[] = " abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
linked_list *ident_list = NULL; /* master list of all items */

/*
    get_ident()

    Gets the identifier for the given object. If an identifier exists, it is
    returned. If not, one is allocated and returned to the user. The
    identifier remains constant as long as the object is in the game.
*/

int
get_ident(struct object *obj_p)
{
    int obj_type = obj_p->o_type;
    linked_list *list_p;           /* pointer into ident_list */
    int new_id = 1;                /* in case we have to allocate */
    struct object *tmp_obj_p;
    struct linked_list *new_place_p = NULL;

    if (identifier(obj_p) != 0)
        return (identifier(obj_p));

    /* no identifier - must allocate one */

    for (list_p = ident_list; list_p != NULL; list_p = next(list_p))
    {
        tmp_obj_p = OBJPTR(list_p);

        if (tmp_obj_p->o_type == obj_type)
        {
            if (identifier(tmp_obj_p) == new_id)
            {
                /* if this id is taken, try next */
                new_place_p = list_p;
                new_id++;
            }
        }
    }

    /*
     * If we get here, the object is not in the list, and we need to add
     * it. The proper id is in new_id, and the place to put it is right
     * after new_place_p.
     */

    list_p = new_list();
    _attach_after(&ident_list, new_place_p, list_p);
    identifier(obj_p) = new_id;
    list_p->data.obj = obj_p;
    return(new_id);
}

/*
    free_ident()

    Frees up an identifier by removing the list entry that contains that item.
    If the item isn't found, nothing is done.
*/

void
free_ident(struct object *obj_p)
{
    linked_list *list_p;

    for (list_p = ident_list; list_p != NULL; list_p = next(list_p))
    {
        if (obj_p == OBJPTR(list_p))
        {
            _detach(&ident_list, list_p);   /* unlink it from the list */
            ur_free(list_p);                /* release link structure */
            break;
        }
    }
}

/*
    unprint_id()

    Converts a printable id from print_letters to the real thing by getting the
    index.
*/

int
unprint_id(char *print_id)
{
    char    *id_p;

    for (id_p = print_letters; id_p != NULL; id_p++)
        if (*id_p == *print_id)
            break;

    return( (int) (id_p - print_letters) );
}

/*
    max_print()

        returns the size of the print list
*/

int
max_print(void)
{
    return(sizeof(print_letters) - 2); /* 1 for blank and 1 for EOS string */
}