/*  FreeJ
 *  (c) Copyright 2001 Denis Roio aka jaromil <jaromil@dyne.org>
 */
 -------------------------------------------------------------------------
   linked list container class

   NOTE: add and rem don't take care of deleting pointers
   that has to be done by the process that creates them and
   knows which inheriting class they are (delete is done in main)
*/

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <linklist.h>
#include <config.h>

Linklist::Linklist() {
  length = 0;
  first = NULL;
  last = NULL;
}

Linklist::~Linklist() {
  clear();
}

/* adds one element at the end of the list */
void Linklist::add(Entry *addr) {
  Entry *ptr;

  if(first==NULL) { /* that's the first entry */
    first = addr;
    first->next = NULL;
    first->prev = NULL;
    last = first;
  } else { /* add the entry to the end */
    ptr = first;
    while(ptr->next!=NULL) ptr = ptr->next;
    ptr->next = addr;
    addr->next = NULL;
    addr->prev = ptr;
    last = addr;
  }
  length++;
}

/* adds an element at the position specified
   if pos is out of bounds adds it at the beginning or the end
   the element occupying allready the position slides down 
   THIS FUNCTION IS NOT YET RELIABLE
*/
void Linklist::add(Entry *addr, int pos) {
  if(length<=pos) { /* adds it at the end */
    add(addr);
    return;
  }

  if(pos<=1) { /* adds it at the beginning */
    first->prev = addr;
    addr->next = first;
    first = addr;
  } else {
    Entry *occ = pick(pos);
    occ->prev->next = addr;
    addr->prev = occ->prev;
    occ->prev = addr;
    addr->next = occ;
  }
  length++;
}

/* removes one element from the list */
void Linklist::rem(int pos) {
  Entry *ptr = pick(pos);
  if(ptr==NULL) return;
  Entry *prev = ptr->prev, *next = ptr->next;

  /* we are on it, now take it out WITHOUT deallocating */
  if(prev!=NULL)
    prev->next = next;
  else first = next;

  if(next!=NULL)
    next->prev = prev;
  else last = prev;

  length--;
}

/* clears the list
   i don't delete filters here because they have to be deleted
   from the procedure creating them. so this call simply discards
   the pointers stored into the linked list. OBJECTS ARE NOT FREED */
void Linklist::clear() {
  length = 0;
  first = NULL;
  last = NULL;
}

/* takes one element from the list
   === STARTING FROM 1 ===
   returns NULL if called with pos=0 or pos>lenght
   returns Entry pointer otherwise */
Entry *Linklist::pick(int pos) {
  if((length<pos)||(pos==0)) return(NULL);
  if(pos==1) return(first);
  if(pos==length) return(last);

  Entry *ptr = first;
  int c;
  for(c=1;c<pos;c++) ptr = ptr->next;

  return(ptr);
}

bool Linklist::moveup(int pos) {
  if(pos<=1) return(false);
  Entry *p = pick(pos);
  Entry *prev = p->prev, *next = p->next, *pp = prev->prev;

  if(next!=NULL) next->prev = prev;
  p->next = prev;
  p->prev = pp;
  prev->next = next;
  prev->prev = p;
  if(pp!=NULL) pp->next = p;

  if(pos==2) first = p;
  if(pos==length) last = prev;
  return(true);
}

bool Linklist::movedown(int pos) {
  if(pos>=length) return(false);
  Entry *p = pick(pos);
  Entry *prev = p->prev, *next = p->next, *nn = next->next;

  if(prev!=NULL) prev->next = next;
  p->prev = next;
  p->next = nn;
  next->prev = prev;
  next->next = p;
  if(nn!=NULL) nn->prev = p;

  if(pos==length-1) last = p;
  if(pos==1) first = next;
  return(true);
}

Select source code:
back to 'READ ME' (main page)
'layer.cpp'(code that handles the printing on the screen)
'layer.h'(class declaration for the layer)
'v4l_layer.cpp'(code that feeds the video image of the person standing in front of the screen to the layer)