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
26static __u32 t2us=1;
27static __u32 us2t=1;
28static double tick_in_usec = 1;
29
30long tc_core_usec2tick(long usec)
31{
32	return usec*tick_in_usec;
33}
34
35long tc_core_tick2usec(long tick)
36{
37	return tick/tick_in_usec;
38}
39
40unsigned tc_calc_xmittime(unsigned rate, unsigned size)
41{
42	return tc_core_usec2tick(1000000*((double)size/rate));
43}
44
45/*
46   rtab[pkt_len>>cell_log] = pkt_xmit_time
47 */
48
49int tc_calc_rtable(unsigned bps, __u32 *rtab, int cell_log, unsigned mtu,
50		   unsigned mpu)
51{
52	int i;
53	unsigned overhead = (mpu >> 8) & 0xFF;
54	mpu = mpu & 0xFF;
55
56	if (mtu == 0)
57		mtu = 2047;
58
59	if (cell_log < 0) {
60		cell_log = 0;
61		while ((mtu>>cell_log) > 255)
62			cell_log++;
63	}
64	for (i=0; i<256; i++) {
65		unsigned sz = (i<<cell_log);
66		if (overhead)
67			sz += overhead;
68		if (sz < mpu)
69			sz = mpu;
70		rtab[i] = tc_core_usec2tick(1000000*((double)sz/bps));
71	}
72	return cell_log;
73}
74
75int tc_core_init()
76{
77	FILE *fp = fopen("/proc/net/psched", "r");
78
79	if (fp == NULL)
80		return -1;
81
82	if (fscanf(fp, "%08x%08x", &t2us, &us2t) != 2) {
83		fclose(fp);
84		return -1;
85	}
86	fclose(fp);
87	tick_in_usec = (double)t2us/us2t;
88	return 0;
89}
90