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/*
* Filters: utility functions
*
* Copyright 1998 Pavel Machek <pavel@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/signal.h>
#include <setjmp.h>
#include "nest/bird.h"
#include "lib/lists.h"
#include "lib/resource.h"
#include "lib/socket.h"
#include "nest/route.h"
#include "nest/protocol.h"
#include "nest/iface.h"
#include "conf/conf.h"
#include "filter/filter.h"
/* Finds n-th item in list linked by right. Trashes pointers in right. */
static struct f_tree *
find_nth(struct f_tree *from, int nth)
{
struct f_tree *pivot;
int lcount = 0, rcount = 0;
struct f_tree *left, *right, *next;
pivot = from;
left = right = NULL;
next = from->right;
while (from = next) {
next = from->right;
if (val_compare(pivot->from, from->from)==1) {
from->right = left;
left = from;
lcount++;
} else {
from->right = right;
right = from;
rcount++;
}
}
if (lcount == nth)
return pivot;
if (lcount < nth)
return find_nth(right, nth-lcount-1);
return find_nth(left, nth);
}
/* Gets list linked by left, finds its median, trashes pointers in right */
static struct f_tree *
find_median(struct f_tree *from)
{
struct f_tree *t = from;
int cnt = 0;
if (!from)
return NULL;
do {
t->right = t->left;
cnt++;
} while (t = t->left);
return find_nth(from, cnt/2);
}
struct f_tree *
find_tree(struct f_tree *t, struct f_val val)
{
if (!t)
return NULL;
if ((val_compare(t->from, val) != 1) &&
(val_compare(t->to, val) != -1))
return t;
if (val_compare(t->from, val) == -1)
return find_tree(t->right, val);
else
return find_tree(t->left, val);
}
/* Gets list linked by left */
struct f_tree *
build_tree(struct f_tree *from)
{
struct f_tree *median, *t = from, *next, *left = NULL, *right = NULL;
median = find_median(from);
if (!median)
return NULL;
do {
next = t->left;
if (t == median)
continue;
if (val_compare(median->from, t->from)==1) {
t->left = left;
left = t;
} else {
t->left = right;
right = t;
}
} while(t = next);
median->left = build_tree(left);
median->right = build_tree(right);
return median;
}
struct f_tree *
f_new_tree(void)
{
struct f_tree * ret;
ret = cfg_alloc(sizeof(struct f_tree));
ret->left = ret->right = NULL;
ret->from.type = ret->to.type = T_VOID;
ret->from.val.i = ret->to.val.i = 0;
ret->data = NULL;
return ret;
}
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