-
Notifications
You must be signed in to change notification settings - Fork 1
/
Copy pathcrc32.lua
167 lines (159 loc) · 6.5 KB
/
crc32.lua
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
local LibDeflate = {}
local string_byte = string.byte
-- Calculate xor for two unsigned 8bit numbers (0 <= a,b <= 255)
local function Xor8(a, b)
local ret = 0
local fact = 128
while fact > a and fact > b do
fact = fact / 2
end
while fact >= 1 do
ret = ret + (((a >= fact or b >= fact)
and (a < fact or b < fact)) and fact or 0)
a = a - ((a >= fact) and fact or 0)
b = b - ((b >= fact) and fact or 0)
fact = fact / 2
end
return ret
end
-- table to cache the result of uint8 xor(x, y) (0<=x,y<=255)
local _xor8_table
local function GenerateXorTable()
assert(not _xor8_table)
_xor8_table = {}
for i = 0, 255 do
local t = {}
_xor8_table[i] = t
for j = 0, 255 do
t[j] = Xor8(i, j)
end
end
end
-- 4 CRC tables.
-- Each table one byte of the value in the traditional crc32 table.
-- _crc_table0 stores the least significant byte.
-- _crc_table3 stores the most significant byte.
-- These tables are generated by the following script.
--[[
for n = 0, 255 do
local c = n
for k = 0, 7 do
local m = c % 2
local d = (c-m)/2
if m > 0 then
c = xor32(0xedb88320, d)
else
c = d
end
end
local c0, c1, c2, c3
c0 = c % 256
c = (c - c0) / 256
c1 = c % 256
c = (c - c1) / 256
c2 = c % 256
c = (c - c2) / 256
c3 = c % 256
_crc_table0[n] = c0
_crc_table1[n] = c1
_crc_table2[n] = c2
_crc_table3[n] = c3
end
]]
local _crc_table0 = {
[0]=0,150,44,186,25,143,53,163,50,164,30,136,43,189,7,145,100,242,72,222,
125,235,81,199,86,192,122,236,79,217,99,245,200,94,228,114,209,71,253,107,
250,108,214,64,227,117,207,89,172,58,128,22,181,35,153,15,158,8,178,36,135,
17,171,61,144,6,188,42,137,31,165,51,162,52,142,24,187,45,151,1,244,98,216,
78,237,123,193,87,198,80,234,124,223,73,243,101,88,206,116,226,65,215,109,
251,106,252,70,208,115,229,95,201,60,170,16,134,37,179,9,159,14,152,34,180,
23,129,59,173,32,182,12,154,57,175,21,131,18,132,62,168,11,157,39,177,68,
210,104,254,93,203,113,231,118,224,90,204,111,249,67,213,232,126,196,82,241,
103,221,75,218,76,246,96,195,85,239,121,140,26,160,54,149,3,185,47,190,
40,146,4,167,49,139,29,176,38,156,10,169,63,133,19,130,20,174,56,155,13,183,
33,212,66,248,110,205,91,225,119,230,112,202,92,255,105,211,69,120,238,84,
194,97,247,77,219,74,220,102,240,83,197,127,233,28,138,48,166,5,147,41,191,
46,184,2,148,55,161,27,141}
local _crc_table1 = {
[0]=0,48,97,81,196,244,165,149,136,184,233,217,76,124,45,29,16,32,113,65,
212,228,181,133,152,168,249,201,92,108,61,13,32,16,65,113,228,212,133,181,
168,152,201,249,108,92,13,61,48,0,81,97,244,196,149,165,184,136,217,233,124,
76,29,45,65,113,32,16,133,181,228,212,201,249,168,152,13,61,108,92,81,97,48,
0,149,165,244,196,217,233,184,136,29,45,124,76,97,81,0,48,165,149,196,244,
233,217,136,184,45,29,76,124,113,65,16,32,181,133,212,228,249,201,152,168,
61,13,92,108,131,179,226,210,71,119,38,22,11,59,106,90,207,255,174,158,147,
163,242,194,87,103,54,6,27,43,122,74,223,239,190,142,163,147,194,242,103,87,
6,54,43,27,74,122,239,223,142,190,179,131,210,226,119,71,22,38,59,11,90,106,
255,207,158,174,194,242,163,147,6,54,103,87,74,122,43,27,142,190,239,223,
210,226,179,131,22,38,119,71,90,106,59,11,158,174,255,207,226,210,131,179,
38,22,71,119,106,90,11,59,174,158,207,255,242,194,147,163,54,6,87,103,122,
74,27,43,190,142,223,239}
local _crc_table2 = {
[0]=0,7,14,9,109,106,99,100,219,220,213,210,182,177,184,191,183,176,185,190,
218,221,212,211,108,107,98,101,1,6,15,8,110,105,96,103,3,4,13,10,181,178,
187,188,216,223,214,209,217,222,215,208,180,179,186,189,2,5,12,11,111,104,
97,102,220,219,210,213,177,182,191,184,7,0,9,14,106,109,100,99,107,108,101,
98,6,1,8,15,176,183,190,185,221,218,211,212,178,181,188,187,223,216,209,214,
105,110,103,96,4,3,10,13,5,2,11,12,104,111,102,97,222,217,208,215,179,180,
189,186,184,191,182,177,213,210,219,220,99,100,109,106,14,9,0,7,15,8,1,6,98,
101,108,107,212,211,218,221,185,190,183,176,214,209,216,223,187,188,181,178,
13,10,3,4,96,103,110,105,97,102,111,104,12,11,2,5,186,189,180,179,215,208,
217,222,100,99,106,109,9,14,7,0,191,184,177,182,210,213,220,219,211,212,221,
218,190,185,176,183,8,15,6,1,101,98,107,108,10,13,4,3,103,96,105,110,209,
214,223,216,188,187,178,181,189,186,179,180,208,215,222,217,102,97,104,111,
11,12,5,2}
local _crc_table3 = {
[0]=0,119,238,153,7,112,233,158,14,121,224,151,9,126,231,144,29,106,243,132,
26,109,244,131,19,100,253,138,20,99,250,141,59,76,213,162,60,75,210,165,53,
66,219,172,50,69,220,171,38,81,200,191,33,86,207,184,40,95,198,177,47,88,
193,182,118,1,152,239,113,6,159,232,120,15,150,225,127,8,145,230,107,28,133,
242,108,27,130,245,101,18,139,252,98,21,140,251,77,58,163,212,74,61,164,211,
67,52,173,218,68,51,170,221,80,39,190,201,87,32,185,206,94,41,176,199,89,46,
183,192,237,154,3,116,234,157,4,115,227,148,13,122,228,147,10,125,240,135,
30,105,247,128,25,110,254,137,16,103,249,142,23,96,214,161,56,79,209,166,63,
72,216,175,54,65,223,168,49,70,203,188,37,82,204,187,34,85,197,178,43,92,
194,181,44,91,155,236,117,2,156,235,114,5,149,226,123,12,146,229,124,11,134,
241,104,31,129,246,111,24,136,255,102,17,143,248,97,22,160,215,78,57,167,
208,73,62,174,217,64,55,169,222,71,48,189,202,83,36,186,205,84,35,179,196,
93,42,180,195,90,45}
--- Calculate the CRC-32 checksum of the string.
--- @param str string the input string to calculate its CRC-32 checksum.
--- @param init_value nil|number The initial crc32 value. If nil, use 0
--- @return number The CRC-32 checksum, which is greater or equal to 0,
--- and less than 2^32 (4294967296).
function LibDeflate:Crc32(str, init_value)
-- TODO: Check argument
local crc = (init_value or 0) % 4294967296
if not _xor8_table then
GenerateXorTable()
end
-- The value of bytes of crc32
-- crc0 is the least significant byte
-- crc3 is the most significant byte
local crc0 = crc % 256
crc = (crc - crc0) / 256
local crc1 = crc % 256
crc = (crc - crc1) / 256
local crc2 = crc % 256
local crc3 = (crc - crc2) / 256
local _xor_vs_255 = _xor8_table[255]
crc0 = _xor_vs_255[crc0]
crc1 = _xor_vs_255[crc1]
crc2 = _xor_vs_255[crc2]
crc3 = _xor_vs_255[crc3]
for i=1, #str do
local byte = string_byte(str, i)
local k = _xor8_table[crc0][byte]
crc0 = _xor8_table[_crc_table0[k] ][crc1]
crc1 = _xor8_table[_crc_table1[k] ][crc2]
crc2 = _xor8_table[_crc_table2[k] ][crc3]
crc3 = _crc_table3[k]
end
crc0 = _xor_vs_255[crc0]
crc1 = _xor_vs_255[crc1]
crc2 = _xor_vs_255[crc2]
crc3 = _xor_vs_255[crc3]
crc = crc0 + crc1*256 + crc2*65536 + crc3*16777216
return crc
end
return LibDeflate