[DCCP]: Move the calc_X routines to dccp_tfrc_lib
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ccids/lib/tfrc_equation.c b/net/dccp/ccids/lib/tfrc_equation.c
new file mode 100644
index 0000000..d2b5933
--- /dev/null
+++ b/net/dccp/ccids/lib/tfrc_equation.c
@@ -0,0 +1,644 @@
+/*
+ * 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 },
+ { 89021, 18339 },
+ { 99147, 20108 },
+ { 108858, 21738 },
+ { 118273, 23260 },
+ { 127474, 24693 },
+ { 136520, 26052 },
+ { 145456, 27348 },
+ { 154316, 28589 },
+ { 163130, 29783 },
+ { 171919, 30935 },
+ { 180704, 32049 },
+ { 189502, 33130 },
+ { 198328, 34180 },
+ { 207194, 35202 },
+ { 216114, 36198 },
+ { 225097, 37172 },
+ { 234153, 38123 },
+ { 243294, 39055 },
+ { 252527, 39968 },
+ { 261861, 40864 },
+ { 271305, 41743 },
+ { 280866, 42607 },
+ { 290553, 43457 },
+ { 300372, 44293 },
+ { 310333, 45117 },
+ { 320441, 45929 },
+ { 330705, 46729 },
+ { 341131, 47518 },
+ { 351728, 48297 },
+ { 362501, 49066 },
+ { 373460, 49826 },
+ { 384609, 50577 },
+ { 395958, 51320 },
+ { 407513, 52054 },
+ { 419281, 52780 },
+ { 431270, 53499 },
+ { 443487, 54211 },
+ { 455940, 54916 },
+ { 468635, 55614 },
+ { 481581, 56306 },
+ { 494785, 56991 },
+ { 508254, 57671 },
+ { 521996, 58345 },
+ { 536019, 59014 },
+ { 550331, 59677 },
+ { 564939, 60335 },
+ { 579851, 60988 },
+ { 595075, 61636 },
+ { 610619, 62279 },
+ { 626491, 62918 },
+ { 642700, 63553 },
+ { 659253, 64183 },
+ { 676158, 64809 },
+ { 693424, 65431 },
+ { 711060, 66050 },
+ { 729073, 66664 },
+ { 747472, 67275 },
+ { 766266, 67882 },
+ { 785464, 68486 },
+ { 805073, 69087 },
+ { 825103, 69684 },
+ { 845562, 70278 },
+ { 866460, 70868 },
+ { 887805, 71456 },
+ { 909606, 72041 },
+ { 931873, 72623 },
+ { 954614, 73202 },
+ { 977839, 73778 },
+ { 1001557, 74352 },
+ { 1025777, 74923 },
+ { 1050508, 75492 },
+ { 1075761, 76058 },
+ { 1101544, 76621 },
+ { 1127867, 77183 },
+ { 1154739, 77741 },
+ { 1182172, 78298 },
+ { 1210173, 78852 },
+ { 1238753, 79405 },
+ { 1267922, 79955 },
+ { 1297689, 80503 },
+ { 1328066, 81049 },
+ { 1359060, 81593 },
+ { 1390684, 82135 },
+ { 1422947, 82675 },
+ { 1455859, 83213 },
+ { 1489430, 83750 },
+ { 1523671, 84284 },
+ { 1558593, 84817 },
+ { 1594205, 85348 },
+ { 1630518, 85878 },
+ { 1667543, 86406 },
+ { 1705290, 86932 },
+ { 1743770, 87457 },
+ { 1782994, 87980 },
+ { 1822973, 88501 },
+ { 1863717, 89021 },
+ { 1905237, 89540 },
+ { 1947545, 90057 },
+ { 1990650, 90573 },
+ { 2034566, 91087 },
+ { 2079301, 91600 },
+ { 2124869, 92111 },
+ { 2171279, 92622 },
+ { 2218543, 93131 },
+ { 2266673, 93639 },
+ { 2315680, 94145 },
+ { 2365575, 94650 },
+ { 2416371, 95154 },
+ { 2468077, 95657 },
+ { 2520707, 96159 },
+ { 2574271, 96660 },
+ { 2628782, 97159 },
+ { 2684250, 97658 },
+ { 2740689, 98155 },
+ { 2798110, 98651 },
+ { 2856524, 99147 },
+ { 2915944, 99641 },
+ { 2976382, 100134 },
+ { 3037850, 100626 },
+ { 3100360, 101117 },
+ { 3163924, 101608 },
+ { 3228554, 102097 },
+ { 3294263, 102586 },
+ { 3361063, 103073 },
+ { 3428966, 103560 },
+ { 3497984, 104045 },
+ { 3568131, 104530 },
+ { 3639419, 105014 },
+ { 3711860, 105498 },
+ { 3785467, 105980 },
+ { 3860253, 106462 },
+ { 3936229, 106942 },
+ { 4013410, 107422 },
+ { 4091808, 107902 },
+ { 4171435, 108380 },
+ { 4252306, 108858 },
+ { 4334431, 109335 },
+ { 4417825, 109811 },
+ { 4502501, 110287 },
+ { 4588472, 110762 },
+ { 4675750, 111236 },
+ { 4764349, 111709 },
+ { 4854283, 112182 },
+ { 4945564, 112654 },
+ { 5038206, 113126 },
+ { 5132223, 113597 },
+ { 5227627, 114067 },
+ { 5324432, 114537 },
+ { 5422652, 115006 },
+ { 5522299, 115474 },
+ { 5623389, 115942 },
+ { 5725934, 116409 },
+ { 5829948, 116876 },
+ { 5935446, 117342 },
+ { 6042439, 117808 },
+ { 6150943, 118273 },
+ { 6260972, 118738 },
+ { 6372538, 119202 },
+ { 6485657, 119665 },
+ { 6600342, 120128 },
+ { 6716607, 120591 },
+ { 6834467, 121053 },
+ { 6953935, 121514 },
+ { 7075025, 121976 },
+ { 7197752, 122436 },
+ { 7322131, 122896 },
+ { 7448175, 123356 },
+ { 7575898, 123815 },
+ { 7705316, 124274 },
+ { 7836442, 124733 },
+ { 7969291, 125191 },
+ { 8103877, 125648 },
+ { 8240216, 126105 },
+ { 8378321, 126562 },
+ { 8518208, 127018 },
+ { 8659890, 127474 },
+ { 8803384, 127930 },
+ { 8948702, 128385 },
+ { 9095861, 128840 },
+ { 9244875, 129294 },
+ { 9395760, 129748 },
+ { 9548529, 130202 },
+ { 9703198, 130655 },
+ { 9859782, 131108 },
+ { 10018296, 131561 },
+ { 10178755, 132014 },
+ { 10341174, 132466 },
+ { 10505569, 132917 },
+ { 10671954, 133369 },
+ { 10840345, 133820 },
+ { 11010757, 134271 },
+ { 11183206, 134721 },
+ { 11357706, 135171 },
+ { 11534274, 135621 },
+ { 11712924, 136071 },
+ { 11893673, 136520 },
+ { 12076536, 136969 },
+ { 12261527, 137418 },
+ { 12448664, 137867 },
+ { 12637961, 138315 },
+ { 12829435, 138763 },
+ { 13023101, 139211 },
+ { 13218974, 139658 },
+ { 13417071, 140106 },
+ { 13617407, 140553 },
+ { 13819999, 140999 },
+ { 14024862, 141446 },
+ { 14232012, 141892 },
+ { 14441465, 142339 },
+ { 14653238, 142785 },
+ { 14867346, 143230 },
+ { 15083805, 143676 },
+ { 15302632, 144121 },
+ { 15523842, 144566 },
+ { 15747453, 145011 },
+ { 15973479, 145456 },
+ { 16201939, 145900 },
+ { 16432847, 146345 },
+ { 16666221, 146789 },
+ { 16902076, 147233 },
+ { 17140429, 147677 },
+ { 17381297, 148121 },
+ { 17624696, 148564 },
+ { 17870643, 149007 },
+ { 18119154, 149451 },
+ { 18370247, 149894 },
+ { 18623936, 150336 },
+ { 18880241, 150779 },
+ { 19139176, 151222 },
+ { 19400759, 151664 },
+ { 19665007, 152107 },
+ { 19931936, 152549 },
+ { 20201564, 152991 },
+ { 20473907, 153433 },
+ { 20748982, 153875 },
+ { 21026807, 154316 },
+ { 21307399, 154758 },
+ { 21590773, 155199 },
+ { 21876949, 155641 },
+ { 22165941, 156082 },
+ { 22457769, 156523 },
+ { 22752449, 156964 },
+ { 23049999, 157405 },
+ { 23350435, 157846 },
+ { 23653774, 158287 },
+ { 23960036, 158727 },
+ { 24269236, 159168 },
+ { 24581392, 159608 },
+ { 24896521, 160049 },
+ { 25214642, 160489 },
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+ { 26517388, 162250 },
+ { 26850728, 162690 },
+ { 27187165, 163130 },
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+ { 28215234, 164449 },
+ { 28564236, 164889 },
+ { 28916423, 165328 },
+ { 29271815, 165768 },
+ { 29630428, 166208 },
+ { 29992281, 166647 },
+ { 30357392, 167087 },
+ { 30725779, 167526 },
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+ { 36657047, 174115 },
+ { 37080329, 174554 },
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+ { 53174435, 189062 },
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+ { 55423634, 190824 },
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+ { 58926806, 193470 },
+ { 59526017, 193911 },
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+ { 65121061, 197886 },
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+ { 238346244, 269881 },
+ { 239994613, 270355 },
+ { 241651183, 270830 },
+ { 243315981, 271305 }
+};
+
+/* 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);