-
Notifications
You must be signed in to change notification settings - Fork 0
/
crc32.js
94 lines (88 loc) · 3.37 KB
/
crc32.js
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
/* crc32.js (C) 2014 SheetJS -- http://sheetjs.com */
/* vim: set ts=2: */
var CRC32 = {};
(function(CRC32) {
CRC32.version = '0.2.1';
/* see perf/crc32table.js */
function signed_crc_table() {
var c, table = new Array(256);
for(var n =0; n != 256; ++n){
c = n;
c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
table[n] = c;
}
return typeof Int32Array !== 'undefined' ? new Int32Array(table) : table;
}
var table = signed_crc_table();
/* charCodeAt is the best approach for binary strings */
var use_buffer = typeof Buffer !== 'undefined';
function crc32_bstr(bstr) {
if(bstr.length > 32768) if(use_buffer) return crc32_buf_8(Buffer(bstr));
var crc = -1, L = bstr.length - 1;
for(var i = 0; i < L;) {
crc = table[(crc ^ bstr.charCodeAt(i++)) & 0xFF] ^ (crc >>> 8);
crc = table[(crc ^ bstr.charCodeAt(i++)) & 0xFF] ^ (crc >>> 8);
}
if(i === L) crc = (crc >>> 8) ^ table[(crc ^ bstr.charCodeAt(i)) & 0xFF];
return crc ^ -1;
}
function crc32_buf(buf) {
if(buf.length > 10000) return crc32_buf_8(buf);
for(var crc = -1, i = 0, L=buf.length-3; i < L;) {
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
}
while(i < L+3) crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
return crc ^ -1;
}
function crc32_buf_8(buf) {
for(var crc = -1, i = 0, L=buf.length-7; i < L;) {
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
}
while(i < L+7) crc = (crc >>> 8) ^ table[(crc^buf[i++])&0xFF];
return crc ^ -1;
}
/* much much faster to intertwine utf8 and crc */
function crc32_str(str) {
for(var crc = -1, i = 0, L=str.length, c, d; i < L;) {
c = str.charCodeAt(i++);
if(c < 0x80) {
crc = (crc >>> 8) ^ table[(crc ^ c) & 0xFF];
} else if(c < 0x800) {
crc = (crc >>> 8) ^ table[(crc ^ (192|((c>>6)&31))) & 0xFF];
crc = (crc >>> 8) ^ table[(crc ^ (128|(c&63))) & 0xFF];
} else if(c >= 0xD800 && c < 0xE000) {
c = (c&1023)+64; d = str.charCodeAt(i++) & 1023;
crc = (crc >>> 8) ^ table[(crc ^ (240|((c>>8)&7))) & 0xFF];
crc = (crc >>> 8) ^ table[(crc ^ (128|((c>>2)&63))) & 0xFF];
crc = (crc >>> 8) ^ table[(crc ^ (128|((d>>6)&15)|(c&3))) & 0xFF];
crc = (crc >>> 8) ^ table[(crc ^ (128|(d&63))) & 0xFF];
} else {
crc = (crc >>> 8) ^ table[(crc ^ (224|((c>>12)&15))) & 0xFF];
crc = (crc >>> 8) ^ table[(crc ^ (128|((c>>6)&63))) & 0xFF];
crc = (crc >>> 8) ^ table[(crc ^ (128|(c&63))) & 0xFF];
}
}
return crc ^ -1;
}
CRC32.table = table;
CRC32.bstr = crc32_bstr;
CRC32.buf = crc32_buf;
CRC32.str = crc32_str;
})(typeof exports !== "undefined" && typeof DO_NOT_EXPORT_CRC === 'undefined' ? exports : CRC32);