mirror of
https://github.com/go-gitea/gitea.git
synced 2024-08-25 13:47:26 +02:00
297 lines
6.1 KiB
Go
297 lines
6.1 KiB
Go
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package brotli
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import "math"
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/* Copyright 2013 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/* Utilities for fast computation of logarithms. */
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func log2FloorNonZero(n uint) uint32 {
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/* TODO: generalize and move to platform.h */
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var result uint32 = 0
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for {
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n >>= 1
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if n == 0 {
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break
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}
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result++
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}
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return result
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}
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/* A lookup table for small values of log2(int) to be used in entropy
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computation.
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", ".join(["%.16ff" % x for x in [0.0]+[log2(x) for x in range(1, 256)]]) */
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var kLog2Table = []float32{
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0.0000000000000000,
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0.0000000000000000,
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1.0000000000000000,
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1.5849625007211563,
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2.0000000000000000,
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2.3219280948873622,
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2.5849625007211561,
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2.8073549220576042,
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3.0000000000000000,
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3.1699250014423126,
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3.3219280948873626,
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3.4594316186372978,
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3.5849625007211565,
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3.7004397181410922,
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3.8073549220576037,
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3.9068905956085187,
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4.0000000000000000,
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4.0874628412503400,
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4.1699250014423122,
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4.2479275134435852,
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4.3219280948873626,
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4.3923174227787607,
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4.4594316186372973,
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4.5235619560570131,
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4.5849625007211570,
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4.6438561897747244,
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4.7004397181410926,
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4.7548875021634691,
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4.8073549220576037,
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4.8579809951275728,
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4.9068905956085187,
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4.9541963103868758,
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5.0000000000000000,
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5.0443941193584534,
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5.0874628412503400,
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5.1292830169449664,
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5.1699250014423122,
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5.2094533656289501,
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5.2479275134435852,
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5.2854022188622487,
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5.3219280948873626,
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5.3575520046180838,
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5.3923174227787607,
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5.4262647547020979,
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5.4594316186372973,
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5.4918530963296748,
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5.5235619560570131,
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5.5545888516776376,
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5.5849625007211570,
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5.6147098441152083,
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5.6438561897747244,
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5.6724253419714961,
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5.7004397181410926,
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5.7279204545631996,
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5.7548875021634691,
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5.7813597135246599,
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5.8073549220576046,
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5.8328900141647422,
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5.8579809951275719,
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5.8826430493618416,
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5.9068905956085187,
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5.9307373375628867,
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5.9541963103868758,
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5.9772799234999168,
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6.0000000000000000,
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6.0223678130284544,
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6.0443941193584534,
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6.0660891904577721,
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6.0874628412503400,
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6.1085244567781700,
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6.1292830169449672,
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6.1497471195046822,
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6.1699250014423122,
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6.1898245588800176,
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6.2094533656289510,
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6.2288186904958804,
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6.2479275134435861,
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6.2667865406949019,
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6.2854022188622487,
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6.3037807481771031,
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6.3219280948873617,
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6.3398500028846252,
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6.3575520046180847,
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6.3750394313469254,
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6.3923174227787598,
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6.4093909361377026,
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6.4262647547020979,
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6.4429434958487288,
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6.4594316186372982,
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6.4757334309663976,
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6.4918530963296748,
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6.5077946401986964,
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6.5235619560570131,
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6.5391588111080319,
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6.5545888516776376,
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6.5698556083309478,
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6.5849625007211561,
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6.5999128421871278,
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6.6147098441152092,
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6.6293566200796095,
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6.6438561897747253,
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6.6582114827517955,
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6.6724253419714952,
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6.6865005271832185,
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6.7004397181410917,
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6.7142455176661224,
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6.7279204545631988,
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6.7414669864011465,
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6.7548875021634691,
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6.7681843247769260,
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6.7813597135246599,
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6.7944158663501062,
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6.8073549220576037,
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6.8201789624151887,
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6.8328900141647422,
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6.8454900509443757,
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6.8579809951275719,
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6.8703647195834048,
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6.8826430493618416,
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6.8948177633079437,
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6.9068905956085187,
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6.9188632372745955,
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6.9307373375628867,
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6.9425145053392399,
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6.9541963103868758,
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6.9657842846620879,
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6.9772799234999168,
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6.9886846867721664,
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7.0000000000000000,
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7.0112272554232540,
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7.0223678130284544,
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7.0334230015374501,
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7.0443941193584534,
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7.0552824355011898,
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7.0660891904577721,
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7.0768155970508317,
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7.0874628412503400,
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7.0980320829605272,
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7.1085244567781700,
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7.1189410727235076,
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7.1292830169449664,
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7.1395513523987937,
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7.1497471195046822,
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7.1598713367783891,
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7.1699250014423130,
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7.1799090900149345,
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7.1898245588800176,
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7.1996723448363644,
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7.2094533656289492,
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7.2191685204621621,
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7.2288186904958804,
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7.2384047393250794,
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7.2479275134435861,
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7.2573878426926521,
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7.2667865406949019,
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7.2761244052742384,
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7.2854022188622487,
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7.2946207488916270,
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7.3037807481771031,
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7.3128829552843557,
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7.3219280948873617,
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7.3309168781146177,
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7.3398500028846243,
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7.3487281542310781,
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7.3575520046180847,
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7.3663222142458151,
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7.3750394313469254,
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7.3837042924740528,
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7.3923174227787607,
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7.4008794362821844,
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7.4093909361377026,
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7.4178525148858991,
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7.4262647547020979,
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7.4346282276367255,
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7.4429434958487288,
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7.4512111118323299,
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7.4594316186372973,
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7.4676055500829976,
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7.4757334309663976,
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7.4838157772642564,
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7.4918530963296748,
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7.4998458870832057,
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7.5077946401986964,
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7.5156998382840436,
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7.5235619560570131,
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7.5313814605163119,
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7.5391588111080319,
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7.5468944598876373,
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7.5545888516776376,
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7.5622424242210728,
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7.5698556083309478,
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7.5774288280357487,
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7.5849625007211561,
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7.5924570372680806,
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7.5999128421871278,
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7.6073303137496113,
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7.6147098441152075,
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7.6220518194563764,
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7.6293566200796095,
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7.6366246205436488,
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7.6438561897747244,
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7.6510516911789290,
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7.6582114827517955,
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7.6653359171851765,
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7.6724253419714952,
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7.6794800995054464,
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7.6865005271832185,
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7.6934869574993252,
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7.7004397181410926,
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7.7073591320808825,
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7.7142455176661224,
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7.7210991887071856,
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7.7279204545631996,
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7.7347096202258392,
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7.7414669864011465,
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7.7481928495894596,
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7.7548875021634691,
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7.7615512324444795,
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7.7681843247769260,
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7.7747870596011737,
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7.7813597135246608,
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7.7879025593914317,
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7.7944158663501062,
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7.8008998999203047,
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7.8073549220576037,
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7.8137811912170374,
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7.8201789624151887,
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7.8265484872909159,
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7.8328900141647422,
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7.8392037880969445,
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7.8454900509443757,
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7.8517490414160571,
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7.8579809951275719,
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7.8641861446542798,
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7.8703647195834048,
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7.8765169465650002,
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7.8826430493618425,
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7.8887432488982601,
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7.8948177633079446,
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7.9008668079807496,
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7.9068905956085187,
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7.9128893362299619,
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7.9188632372745955,
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7.9248125036057813,
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7.9307373375628867,
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7.9366379390025719,
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7.9425145053392399,
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7.9483672315846778,
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7.9541963103868758,
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7.9600019320680806,
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7.9657842846620870,
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7.9715435539507720,
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7.9772799234999168,
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7.9829935746943104,
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7.9886846867721664,
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7.9943534368588578,
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}
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/* Faster logarithm for small integers, with the property of log2(0) == 0. */
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func fastLog2(v uint) float64 {
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if v < uint(len(kLog2Table)) {
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return float64(kLog2Table[v])
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}
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return math.Log2(float64(v))
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}
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