--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/urogue/ident.c	Tue Jan 31 19:56:04 2017 -0500
@@ -0,0 +1,136 @@
+/*
+    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 */
+}