/*
Copyright (C) 1994-1995 Apogee Software, Ltd.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

Modifications for JonoF's port by Jonathon Fowler (jonof@edgenetwk.com)
*/
/**********************************************************************
   module: LL_MAN.C

   author: James R. Dose
   date:   January 1, 1994

   Linked list management routines.

   (c) Copyright 1994 James R. Dose.  All Rights Reserved.
**********************************************************************/

#include <stddef.h>
#include "ll_man.h"

#define OFFSET( structure, offset ) \
   ( *( ( char ** )&( structure )[ offset ] ) )


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

   Memory locked functions:

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


void LL_AddNode
(
    char *item,
    char **head,
    char **tail,
    int next,
    int prev
)

{
    OFFSET(item, prev) = NULL;
    OFFSET(item, next) = *head;

    if (*head)
    {
        OFFSET(*head, prev) = item;
    }
    else
    {
        *tail = item;
    }

    *head = item;
}

void LL_RemoveNode
(
    char *item,
    char **head,
    char **tail,
    int next,
    int prev
)

{
    if (OFFSET(item, prev) == NULL)
    {
        *head = OFFSET(item, next);
    }
    else
    {
        OFFSET(OFFSET(item, prev), next) = OFFSET(item, next);
    }

    if (OFFSET(item, next) == NULL)
    {
        *tail = OFFSET(item, prev);
    }
    else
    {
        OFFSET(OFFSET(item, next), prev) = OFFSET(item, prev);
    }

    OFFSET(item, next) = NULL;
    OFFSET(item, prev) = NULL;
}