jacobson_karels: New module

[ccan] / ccan / jacobson_karels / jacobson_karels.h

diff --git a/ccan/jacobson_karels/jacobson_karels.h b/ccan/jacobson_karels/jacobson_karels.h
new file mode 100644 (file)
index 0000000..0e9bc2d
--- /dev/null
+++ b/ccan/jacobson_karels/jacobson_karels.h
@@ -0,0 +1,35 @@
+/* Licensed under LGPLv2.1+ - see LICENSE file for details */
+#ifndef CCAN_JACOBSON_KARELS_H
+#define CCAN_JACOBSON_KARELS_H
+
+#include "config.h"
+
+#include <ccan/minmax/minmax.h>
+
+#define JACOBSON_KARELS(_name, _type, _a1, _a2, _b1, _b2, _g, _k) \
+       struct _name##_state { \
+               _type rtt, variance; \
+       }; \
+       static void _name##_init(struct _name##_state *s, \
+                                _type rtt0, _type var0)  \
+       { \
+               s->rtt = rtt0; \
+               s->variance = var0; \
+       } \
+       static void _name##_update(struct _name##_state *s, _type sample) \
+       { \
+               _type diff = sample - s->rtt; \
+               s->rtt += (_a2) * diff / ((_a1) + (_a2)); \
+               diff = (diff < 0) ? -diff : diff; \
+               s->variance = ((_b1)*s->variance + (_b2) * diff) \
+                       / ((_b1) + (_b2));                       \
+       } \
+       static _type _name##_timeout(struct _name##_state *s, \
+                                    _type tmin, _type tmax)  \
+       { \
+               return clamp((_g) * s->rtt + (_k)*s->variance, tmin, tmax); \
+       }
+
+JACOBSON_KARELS(jacobson_karels, unsigned long, 7, 1, 3, 1, 1, 4)
+
+#endif /* CCAN_JACOBSON_KARELS_H */