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   1 /* Licensed under LGPLv2.1+ - see LICENSE file for details */
   2 #ifndef CCAN_JACOBSON_KARELS_H
   3 #define CCAN_JACOBSON_KARELS_H
   4
   5 #include "config.h"
   6
   7 #include <ccan/minmax/minmax.h>
   8
   9 #define JACOBSON_KARELS(_name, _type, _a1, _a2, _b1, _b2, _g, _k) \
  10         struct _name##_state { \
  11                 _type rtt, variance; \
  12         }; \
  13         static void _name##_init(struct _name##_state *s, \
  14                                  _type rtt0, _type var0)  \
  15         { \
  16                 s->rtt = rtt0; \
  17                 s->variance = var0; \
  18         } \
  19         static void _name##_update(struct _name##_state *s, _type sample) \
  20         { \
  21                 _type diff = sample - s->rtt; \
  22                 s->rtt += (_a2) * diff / ((_a1) + (_a2)); \
  23                 diff = (diff < 0) ? -diff : diff; \
  24                 s->variance = ((_b1)*s->variance + (_b2) * diff) \
  25                         / ((_b1) + (_b2));                       \
  26         } \
  27         static _type _name##_timeout(struct _name##_state *s, \
  28                                      _type tmin, _type tmax)  \
  29         { \
  30                 return clamp((_g) * s->rtt + (_k)*s->variance, tmin, tmax); \
  31         }
  32
  33 JACOBSON_KARELS(jacobson_karels, unsigned long, 7, 1, 3, 1, 1, 4)
  34
  35 #endif /* CCAN_JACOBSON_KARELS_H */