/* $VER: ar lists.c V0.1 (31.01.98)
 *
 * This file is part of ar, a portable archive maintanance
 * utility for normal and BSD-style archives.
 * Copyright (c) 1999  Frank Wille
 *
 * ar is freeware and part of the portable and retargetable ANSI C
 * compiler vbcc, copyright (c) 1995-99 by Volker Barthelmann.
 * ar may be freely redistributed as long as no modifications are
 * made and nothing is charged for it. Non-commercial usage is allowed
 * without any restrictions.
 * EVERY PRODUCT OR PROGRAM DERIVED DIRECTLY FROM MY SOURCE MAY NOT BE
 * SOLD COMMERCIALLY WITHOUT PERMISSION FROM THE AUTHOR.
 *
 *
 * v0.1  (31.01.99) phx
 *       First working version, which only supports 'q' (quick append)
 *       and 't' (table of contents), reads and writes normals and
 *       BSD-style archives. Symbol table will not be created!
 * v0.0  (29.01.99) phx
 *       File created.
 */

#include "ar.h"
#include "lists.h"



void initlist(struct list *l)
/* initializes a list structure */
{
  l->first = (struct node *)&l->dummy;
  l->dummy = NULL;
  l->last = (struct node *)&l->first;
}


void insertbefore(struct node *n,struct node *sn)
/* insert node n directly before node sn */
/* sn must be a real node - no dummy nodes allowed! */
{
  struct node *pn = sn->pred;

  n->next = sn;
  n->pred = pn;
  pn->next = sn->pred = n;
}


void insertbehind(struct node *pn,struct node *n)
/* insert node n directly behind node pn */
/* pn must be a real node - no dummy nodes allowed! */
{
  struct node *sn = pn->next;

  n->next = sn;
  n->pred = pn;
  pn->next = sn->pred = n;
}


void addhead(struct list *l,struct node *n)
/* add node as first element of list */
{
  struct node *fn = l->first;

  n->pred = fn->pred;
  fn->pred = n;
  n->next = fn;
  l->first = n;
}


void addtail(struct list *l,struct node *n)
/* add node as last element of list */
{
  struct node *ln = l->last;

  n->next = ln->next;
  ln->next = n;
  n->pred = ln;
  l->last = n;
}