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/*
* ngtcp2
*
* Copyright (c) 2021 ngtcp2 contributors
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* Translated to C from the original C++ code
* https://quiche.googlesource.com/quiche/+/5be974e29f7e71a196e726d6e2272676d33ab77d/quic/core/congestion_control/windowed_filter.h
* with the following license:
*
* // Copyright (c) 2016 The Chromium Authors. All rights reserved.
* // Use of this source code is governed by a BSD-style license that can be
* // found in the LICENSE file.
*/
#include "ngtcp2_window_filter.h"
#include <string.h>
void ngtcp2_window_filter_init(ngtcp2_window_filter *wf,
uint64_t window_length) {
wf->window_length = window_length;
memset(wf->estimates, 0, sizeof(wf->estimates));
}
void ngtcp2_window_filter_update(ngtcp2_window_filter *wf, uint64_t new_sample,
uint64_t new_time) {
if (wf->estimates[0].sample == 0 || new_sample > wf->estimates[0].sample ||
new_time - wf->estimates[2].time > wf->window_length) {
ngtcp2_window_filter_reset(wf, new_sample, new_time);
return;
}
if (new_sample > wf->estimates[1].sample) {
wf->estimates[1].sample = new_sample;
wf->estimates[1].time = new_time;
wf->estimates[2] = wf->estimates[1];
} else if (new_sample > wf->estimates[2].sample) {
wf->estimates[2].sample = new_sample;
wf->estimates[2].time = new_time;
}
if (new_time - wf->estimates[0].time > wf->window_length) {
wf->estimates[0] = wf->estimates[1];
wf->estimates[1] = wf->estimates[2];
wf->estimates[2].sample = new_sample;
wf->estimates[2].time = new_time;
if (new_time - wf->estimates[0].time > wf->window_length) {
wf->estimates[0] = wf->estimates[1];
wf->estimates[1] = wf->estimates[2];
}
return;
}
if (wf->estimates[1].sample == wf->estimates[0].sample &&
new_time - wf->estimates[1].time > wf->window_length >> 2) {
wf->estimates[2].sample = new_sample;
wf->estimates[2].time = new_time;
wf->estimates[1] = wf->estimates[2];
return;
}
if (wf->estimates[2].sample == wf->estimates[1].sample &&
new_time - wf->estimates[2].time > wf->window_length >> 1) {
wf->estimates[2].sample = new_sample;
wf->estimates[2].time = new_time;
}
}
void ngtcp2_window_filter_reset(ngtcp2_window_filter *wf, uint64_t new_sample,
uint64_t new_time) {
wf->estimates[0].sample = new_sample;
wf->estimates[0].time = new_time;
wf->estimates[1] = wf->estimates[2] = wf->estimates[0];
}
uint64_t ngtcp2_window_filter_get_best(ngtcp2_window_filter *wf) {
return wf->estimates[0].sample;
}
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