/CRC32.lua
Lua | 173 lines | 116 code | 21 blank | 36 comment | 9 complexity | 8d83893566c6895730d78f8d26dc3df6 MD5 | raw file
- --Copyright (c) 2007-2008 Neil Richardson (nrich@iinet.net.au)
- --
- --Permission is hereby granted, free of charge, to any person obtaining a copy
- --of this software and associated documentation files (the "Software"), to deal
- --in the Software without restriction, including without limitation the rights
- --to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- --copies of the Software, and to permit persons to whom the Software is
- --furnished to do so, subject to the following conditions:
- --
- --The above copyright notice and this permission notice shall be included in all
- --copies or substantial portions of the Software.
- --
- --THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- --IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- --FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- --AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- --LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- --OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
- --IN THE SOFTWARE.
- module('CRC32', package.seeall)
- local max = 2^32 -1
- local CRC32 = {
- 0,79764919,159529838,222504665,319059676,
- 398814059,445009330,507990021,638119352,
- 583659535,797628118,726387553,890018660,
- 835552979,1015980042,944750013,1276238704,
- 1221641927,1167319070,1095957929,1595256236,
- 1540665371,1452775106,1381403509,1780037320,
- 1859660671,1671105958,1733955601,2031960084,
- 2111593891,1889500026,1952343757,2552477408,
- 2632100695,2443283854,2506133561,2334638140,
- 2414271883,2191915858,2254759653,3190512472,
- 3135915759,3081330742,3009969537,2905550212,
- 2850959411,2762807018,2691435357,3560074640,
- 3505614887,3719321342,3648080713,3342211916,
- 3287746299,3467911202,3396681109,4063920168,
- 4143685023,4223187782,4286162673,3779000052,
- 3858754371,3904687514,3967668269,881225847,
- 809987520,1023691545,969234094,662832811,
- 591600412,771767749,717299826,311336399,
- 374308984,453813921,533576470,25881363,
- 88864420,134795389,214552010,2023205639,
- 2086057648,1897238633,1976864222,1804852699,
- 1867694188,1645340341,1724971778,1587496639,
- 1516133128,1461550545,1406951526,1302016099,
- 1230646740,1142491917,1087903418,2896545431,
- 2825181984,2770861561,2716262478,3215044683,
- 3143675388,3055782693,3001194130,2326604591,
- 2389456536,2200899649,2280525302,2578013683,
- 2640855108,2418763421,2498394922,3769900519,
- 3832873040,3912640137,3992402750,4088425275,
- 4151408268,4197601365,4277358050,3334271071,
- 3263032808,3476998961,3422541446,3585640067,
- 3514407732,3694837229,3640369242,1762451694,
- 1842216281,1619975040,1682949687,2047383090,
- 2127137669,1938468188,2001449195,1325665622,
- 1271206113,1183200824,1111960463,1543535498,
- 1489069629,1434599652,1363369299,622672798,
- 568075817,748617968,677256519,907627842,
- 853037301,1067152940,995781531,51762726,
- 131386257,177728840,240578815,269590778,
- 349224269,429104020,491947555,4046411278,
- 4126034873,4172115296,4234965207,3794477266,
- 3874110821,3953728444,4016571915,3609705398,
- 3555108353,3735388376,3664026991,3290680682,
- 3236090077,3449943556,3378572211,3174993278,
- 3120533705,3032266256,2961025959,2923101090,
- 2868635157,2813903052,2742672763,2604032198,
- 2683796849,2461293480,2524268063,2284983834,
- 2364738477,2175806836,2238787779,1569362073,
- 1498123566,1409854455,1355396672,1317987909,
- 1246755826,1192025387,1137557660,2072149281,
- 2135122070,1912620623,1992383480,1753615357,
- 1816598090,1627664531,1707420964,295390185,
- 358241886,404320391,483945776,43990325,
- 106832002,186451547,266083308,932423249,
- 861060070,1041341759,986742920,613929101,
- 542559546,756411363,701822548,3316196985,
- 3244833742,3425377559,3370778784,3601682597,
- 3530312978,3744426955,3689838204,3819031489,
- 3881883254,3928223919,4007849240,4037393693,
- 4100235434,4180117107,4259748804,2310601993,
- 2373574846,2151335527,2231098320,2596047829,
- 2659030626,2470359227,2550115596,2947551409,
- 2876312838,2788305887,2733848168,3165939309,
- 3094707162,3040238851,2985771188,
- }
- local function xor(a, b)
- local calc = 0
- for i = 32, 0, -1 do
- local val = 2 ^ i
- local aa = false
- local bb = false
- if a == 0 then
- calc = calc + b
- break
- end
- if b == 0 then
- calc = calc + a
- break
- end
- if a >= val then
- aa = true
- a = a - val
- end
- if b >= val then
- bb = true
- b = b - val
- end
- if not (aa and bb) and (aa or bb) then
- calc = calc + val
- end
- end
- return calc
- end
- local function lshift(num, left)
- local res = num * (2 ^ left)
- return res % (2 ^ 32)
- end
- local function rshift(num, right)
- local res = num / (2 ^ right)
- return math.floor(res)
- end
- function Hash(str)
- local count = string.len(tostring(str))
- local crc = max
-
- local i = 1
- while count > 0 do
- local byte = string.byte(str, i)
- crc = xor(lshift(crc, 8), CRC32[xor(rshift(crc, 24), byte) + 1])
- i = i + 1
- count = count - 1
- end
- return crc
- end
- --
- -- CRC32.lua
- --
- -- A pure Lua implementation of a CRC32 hashing algorithm. Slower than using a C implemtation,
- -- but useful having no other dependancies.
- --
- --
- -- Synopsis
- --
- -- require('CRC32')
- --
- -- crchash = CRC32.Hash('a string')
- --
- -- Methods:
- --
- -- hashval = CRC32.Hash(val)
- -- Calculates and returns (as an integer) the CRC32 hash of the parameter 'val'.