From a0e0018c9a7ef5ce7f6d2c3ae16aecbbd16a8f67 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sat, 4 May 2024 16:18:53 +0200
Subject: Adding upstream version 6.1.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 tc/tc_red.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 tc/tc_red.c

(limited to 'tc/tc_red.c')

diff --git a/tc/tc_red.c b/tc/tc_red.c
new file mode 100644
index 0000000..88f5ff3
--- /dev/null
+++ b/tc/tc_red.c
@@ -0,0 +1,124 @@
+/*
+ * tc_red.c		RED maintenance routines.
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <math.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <string.h>
+
+#include "utils.h"
+#include "tc_core.h"
+#include "tc_util.h"
+#include "tc_red.h"
+
+/*
+   Plog = log(prob/(qmax - qmin))
+ */
+int tc_red_eval_P(unsigned int qmin, unsigned int qmax, double prob)
+{
+	int i = qmax - qmin;
+
+	if (!i)
+		return 0;
+	if (i < 0)
+		return -1;
+
+	prob /= i;
+
+	for (i = 0; i < 32; i++) {
+		if (prob > 1.0)
+			break;
+		prob *= 2;
+	}
+	if (i >= 32)
+		return -1;
+	return i;
+}
+
+/*
+   burst + 1 - qmin/avpkt < (1-(1-W)^burst)/W
+ */
+
+int tc_red_eval_ewma(unsigned int qmin, unsigned int burst, unsigned int avpkt)
+{
+	int wlog = 1;
+	double W = 0.5;
+	double a = (double)burst + 1 - (double)qmin/avpkt;
+
+	if (a < 1.0) {
+		fprintf(stderr, "tc_red_eval_ewma() burst %u is too small ? Try burst %u\n",
+				burst, 1 + qmin/avpkt);
+		return -1;
+	}
+	for (wlog = 1; wlog < 32; wlog++, W /= 2) {
+		if (a <= (1 - pow(1-W, burst))/W)
+			return wlog;
+	}
+	return -1;
+}
+
+/*
+   Stab[t>>Scell_log] = -log(1-W) * t/xmit_time
+ */
+
+int tc_red_eval_idle_damping(int Wlog, unsigned int avpkt, unsigned int bps, __u8 *sbuf)
+{
+	double xmit_time = tc_calc_xmittime(bps, avpkt);
+	double lW = -log(1.0 - 1.0/(1<<Wlog))/xmit_time;
+	double maxtime = 31/lW;
+	int clog;
+	int i;
+
+	for (clog = 0; clog < 32; clog++) {
+		if (maxtime/(1<<clog) < 512)
+			break;
+	}
+	if (clog >= 32)
+		return -1;
+
+	sbuf[0] = 0;
+	for (i = 1; i < 255; i++) {
+		sbuf[i] = (i<<clog)*lW;
+		if (sbuf[i] > 31)
+			sbuf[i] = 31;
+	}
+	sbuf[255] = 31;
+	return clog;
+}
+
+void tc_red_print_flags(__u32 flags)
+{
+	if (flags & TC_RED_ECN)
+		print_bool(PRINT_ANY, "ecn", "ecn ", true);
+	else
+		print_bool(PRINT_ANY, "ecn", NULL, false);
+
+	if (flags & TC_RED_HARDDROP)
+		print_bool(PRINT_ANY, "harddrop", "harddrop ", true);
+	else
+		print_bool(PRINT_ANY, "harddrop", NULL, false);
+
+	if (flags & TC_RED_ADAPTATIVE)
+		print_bool(PRINT_ANY, "adaptive", "adaptive ", true);
+	else
+		print_bool(PRINT_ANY, "adaptive", NULL, false);
+
+	if (flags & TC_RED_NODROP)
+		print_bool(PRINT_ANY, "nodrop", "nodrop ", true);
+	else
+		print_bool(PRINT_ANY, "nodrop", NULL, false);
+}
-- 
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