tc/tc_estimator.c

   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 <fcntl.h>
  17 #include <math.h>
  18 #include <sys/socket.h>
  19 #include <netinet/in.h>
  20 #include <arpa/inet.h>
  21 #include <string.h>
  22
  23 #include "utils.h"
  24 #include "tc_core.h"
  25
  26 int tc_setup_estimator(unsigned int A, unsigned int time_const, struct tc_estimator *est)
  27 {
  28         for (est->interval = 0; est->interval <= 5; est->interval++) {
  29                 if (A <= (1<<est->interval)*(TIME_UNITS_PER_SEC/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
  38                 if (A/(-log(w)) > time_const)
  39                         break;
  40         }
  41         est->ewma_log--;
  42         if (est->ewma_log == 0 || est->ewma_log >= 31)
  43                 return -1;
  44         return 0;
  45 }