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diff --git a/net/dccp/ccids/lib/tfrc_equation.c b/net/dccp/ccids/lib/tfrc_equation.c
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+/*
+ * net/dccp/ccids/lib/tfrc_equation.c
+ *
+ * Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
+ * Copyright (c) 2005 Ian McDonald <iam4@cs.waikato.ac.nz>
+ * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
+ *
+ * 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.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+
+#include <asm/bug.h>
+#include <asm/div64.h>
+
+#include "tfrc.h"
+
+#define TFRC_CALC_X_ARRSIZE 500
+
+#define TFRC_CALC_X_SPLIT 50000
+/* equivalent to 0.05 */
+
+static const u32 tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE][2] = {
+ { 37172, 8172 },
+ { 53499, 11567 },
+ { 66664, 14180 },
+ { 78298, 16388 },
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+};
+
+/* Calculate the send rate as per section 3.1 of RFC3448
+
+Returns send rate in bytes per second
+
+Integer maths and lookups are used as not allowed floating point in kernel
+
+The function for Xcalc as per section 3.1 of RFC3448 is:
+
+X = s
+ -------------------------------------------------------------
+ R*sqrt(2*b*p/3) + (t_RTO * (3*sqrt(3*b*p/8) * p * (1+32*p^2)))
+
+where
+X is the trasmit rate in bytes/second
+s is the packet size in bytes
+R is the round trip time in seconds
+p is the loss event rate, between 0 and 1.0, of the number of loss events
+ as a fraction of the number of packets transmitted
+t_RTO is the TCP retransmission timeout value in seconds
+b is the number of packets acknowledged by a single TCP acknowledgement
+
+we can assume that b = 1 and t_RTO is 4 * R. With this the equation becomes:
+
+X = s
+ -----------------------------------------------------------------------
+ R * sqrt(2 * p / 3) + (12 * R * (sqrt(3 * p / 8) * p * (1 + 32 * p^2)))
+
+
+which we can break down into:
+
+X = s
+ --------
+ R * f(p)
+
+where f(p) = sqrt(2 * p / 3) + (12 * sqrt(3 * p / 8) * p * (1 + 32 * p * p))
+
+Function parameters:
+s - bytes
+R - RTT in usecs
+p - loss rate (decimal fraction multiplied by 1,000,000)
+
+Returns Xcalc in bytes per second
+
+DON'T alter this code unless you run test cases against it as the code
+has been manipulated to stop underflow/overlow.
+
+*/
+u32 tfrc_calc_x(u16 s, u32 R, u32 p)
+{
+ int index;
+ u32 f;
+ u64 tmp1, tmp2;
+
+ if (p < TFRC_CALC_X_SPLIT)
+ index = (p / (TFRC_CALC_X_SPLIT / TFRC_CALC_X_ARRSIZE)) - 1;
+ else
+ index = (p / (1000000 / TFRC_CALC_X_ARRSIZE)) - 1;
+
+ if (index < 0)
+ /* p should be 0 unless there is a bug in my code */
+ index = 0;
+
+ if (R == 0)
+ R = 1; /* RTT can't be zero or else divide by zero */
+
+ BUG_ON(index >= TFRC_CALC_X_ARRSIZE);
+
+ if (p >= TFRC_CALC_X_SPLIT)
+ f = tfrc_calc_x_lookup[index][0];
+ else
+ f = tfrc_calc_x_lookup[index][1];
+
+ tmp1 = ((u64)s * 100000000);
+ tmp2 = ((u64)R * (u64)f);
+ do_div(tmp2, 10000);
+ do_div(tmp1, tmp2);
+ /* Don't alter above math unless you test due to overflow on 32 bit */
+
+ return (u32)tmp1;
+}
+
+EXPORT_SYMBOL_GPL(tfrc_calc_x);
+
+/*
+ * args: fvalue - function value to match
+ * returns: p closest to that value
+ *
+ * both fvalue and p are multiplied by 1,000,000 to use ints
+ */
+u32 tfrc_calc_x_reverse_lookup(u32 fvalue)
+{
+ int ctr = 0;
+ int small;
+
+ if (fvalue < tfrc_calc_x_lookup[0][1])
+ return 0;
+
+ if (fvalue <= tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE - 1][1])
+ small = 1;
+ else if (fvalue > tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE - 1][0])
+ return 1000000;
+ else
+ small = 0;
+
+ while (fvalue > tfrc_calc_x_lookup[ctr][small])
+ ctr++;
+
+ if (small)
+ return TFRC_CALC_X_SPLIT * ctr / TFRC_CALC_X_ARRSIZE;
+ else
+ return 1000000 * ctr / TFRC_CALC_X_ARRSIZE;
+}
+
+EXPORT_SYMBOL_GPL(tfrc_calc_x_reverse_lookup);
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