1/*
2 * tc_core.c		TC core library.
3 *
4 *		This program is free software; you can redistribute it and/or
5 *		modify it under the terms of the GNU General Public License
6 *		as published by the Free Software Foundation; either version
7 *		2 of the License, or (at your option) any later version.
8 *
9 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
10 *
11 */
12
13#include <stdio.h>
14#include <stdlib.h>
15#include <unistd.h>
16#include <syslog.h>
17#include <fcntl.h>
18#include <math.h>
19#include <sys/socket.h>
20#include <netinet/in.h>
21#include <arpa/inet.h>
22#include <string.h>
23
24#include "tc_core.h"
25
26int tc_setup_estimator(unsigned A, unsigned time_const, struct tc_estimator *est)
27{
28	for (est->interval=0; est->interval<=5; est->interval++) {
29		if (A <= (1<<est->interval)*(1000000/4))
30			break;
31	}
32	if (est->interval > 5)
33		return -1;
34	est->interval -= 2;
35	for (est->ewma_log=1; est->ewma_log<32; est->ewma_log++) {
36		double w = 1.0 - 1.0/(1<<est->ewma_log);
37		if (A/(-log(w)) > time_const)
38			break;
39	}
40	est->ewma_log--;
41	if (est->ewma_log==0 || est->ewma_log >= 31)
42		return -1;
43	return 0;
44}
45