171 lines
5.4 KiB
Lua
171 lines
5.4 KiB
Lua
--Copyright (c) 2007-2008 Neil Richardson (nrich@iinet.net.au)
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--
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--Permission is hereby granted, free of charge, to any person obtaining a copy
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--of this software and associated documentation files (the "Software"), to deal
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--in the Software without restriction, including without limitation the rights
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--to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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--copies of the Software, and to permit persons to whom the Software is
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--furnished to do so, subject to the following conditions:
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--
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--The above copyright notice and this permission notice shall be included in all
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--copies or substantial portions of the Software.
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--
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--THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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--IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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--FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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--AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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--LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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--OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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--IN THE SOFTWARE.
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local max = 2^32 -1
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local CRC32 = {
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0,79764919,159529838,222504665,319059676,
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398814059,445009330,507990021,638119352,
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583659535,797628118,726387553,890018660,
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835552979,1015980042,944750013,1276238704,
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1221641927,1167319070,1095957929,1595256236,
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1540665371,1452775106,1381403509,1780037320,
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1859660671,1671105958,1733955601,2031960084,
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2111593891,1889500026,1952343757,2552477408,
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2632100695,2443283854,2506133561,2334638140,
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2414271883,2191915858,2254759653,3190512472,
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3135915759,3081330742,3009969537,2905550212,
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2850959411,2762807018,2691435357,3560074640,
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3505614887,3719321342,3648080713,3342211916,
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3287746299,3467911202,3396681109,4063920168,
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4143685023,4223187782,4286162673,3779000052,
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3858754371,3904687514,3967668269,881225847,
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809987520,1023691545,969234094,662832811,
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591600412,771767749,717299826,311336399,
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374308984,453813921,533576470,25881363,
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88864420,134795389,214552010,2023205639,
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2086057648,1897238633,1976864222,1804852699,
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1867694188,1645340341,1724971778,1587496639,
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1516133128,1461550545,1406951526,1302016099,
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1230646740,1142491917,1087903418,2896545431,
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2825181984,2770861561,2716262478,3215044683,
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3143675388,3055782693,3001194130,2326604591,
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2389456536,2200899649,2280525302,2578013683,
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2640855108,2418763421,2498394922,3769900519,
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3832873040,3912640137,3992402750,4088425275,
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4151408268,4197601365,4277358050,3334271071,
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3263032808,3476998961,3422541446,3585640067,
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3514407732,3694837229,3640369242,1762451694,
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1842216281,1619975040,1682949687,2047383090,
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2127137669,1938468188,2001449195,1325665622,
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1271206113,1183200824,1111960463,1543535498,
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1489069629,1434599652,1363369299,622672798,
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568075817,748617968,677256519,907627842,
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853037301,1067152940,995781531,51762726,
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131386257,177728840,240578815,269590778,
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349224269,429104020,491947555,4046411278,
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4126034873,4172115296,4234965207,3794477266,
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3874110821,3953728444,4016571915,3609705398,
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3555108353,3735388376,3664026991,3290680682,
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3236090077,3449943556,3378572211,3174993278,
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3120533705,3032266256,2961025959,2923101090,
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2868635157,2813903052,2742672763,2604032198,
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2683796849,2461293480,2524268063,2284983834,
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2364738477,2175806836,2238787779,1569362073,
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1498123566,1409854455,1355396672,1317987909,
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1246755826,1192025387,1137557660,2072149281,
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2135122070,1912620623,1992383480,1753615357,
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1816598090,1627664531,1707420964,295390185,
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358241886,404320391,483945776,43990325,
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106832002,186451547,266083308,932423249,
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861060070,1041341759,986742920,613929101,
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542559546,756411363,701822548,3316196985,
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3244833742,3425377559,3370778784,3601682597,
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3530312978,3744426955,3689838204,3819031489,
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3881883254,3928223919,4007849240,4037393693,
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4100235434,4180117107,4259748804,2310601993,
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233574846,2151335527,2231098320,2596047829,
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2659030626,2470359227,2550115596,2947551409,
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2876312838,2788305887,2733848168,3165939309,
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3094707162,3040238851,2985771188,
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}
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local function xor(a, b)
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local calc = 0
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for i = 32, 0, -1 do
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local val = 2 ^ i
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local aa = false
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local bb = false
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if a == 0 then
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calc = calc + b
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break
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end
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if b == 0 then
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calc = calc + a
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break
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end
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if a >= val then
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aa = true
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a = a - val
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end
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if b >= val then
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bb = true
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b = b - val
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end
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if not (aa and bb) and (aa or bb) then
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calc = calc + val
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end
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end
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return calc
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end
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local function lshift(num, left)
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local res = num * (2 ^ left)
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return res % (2 ^ 32)
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end
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local function rshift(num, right)
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local res = num / (2 ^ right)
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return math.floor(res)
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end
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local function crc32(str)
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local count = string.len(tostring(str))
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local crc = max
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local i = 1
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while count > 0 do
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local byte = string.byte(str, i)
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crc = xor(lshift(crc, 8), CRC32[xor(rshift(crc, 24), byte) + 1])
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i = i + 1
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count = count - 1
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end
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return crc
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end
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return crc32
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--
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-- CRC32.lua
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--
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-- A pure Lua implementation of a CRC32 hashing algorithm. Slower than using a C implemtation,
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-- but useful having no other dependencies.
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--
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--
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-- Synopsis
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--
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-- require('CRC32')
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--
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-- crchash = CRC32.Hash('a string')
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--
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-- Methods:
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--
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-- hashval = CRC32.Hash(val)
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-- Calculates and returns (as an integer) the CRC32 hash of the parameter 'val'.
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