mirror of
https://github.com/idanoo/GoScrobble.git
synced 2024-11-23 00:45:16 +00:00
52 lines
1.6 KiB
JavaScript
52 lines
1.6 KiB
JavaScript
'use strict';
|
|
|
|
// Note: adler32 takes 12% for level 0 and 2% for level 6.
|
|
// It isn't worth it to make additional optimizations as in original.
|
|
// Small size is preferable.
|
|
|
|
// (C) 1995-2013 Jean-loup Gailly and Mark Adler
|
|
// (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin
|
|
//
|
|
// This software is provided 'as-is', without any express or implied
|
|
// warranty. In no event will the authors be held liable for any damages
|
|
// arising from the use of this software.
|
|
//
|
|
// Permission is granted to anyone to use this software for any purpose,
|
|
// including commercial applications, and to alter it and redistribute it
|
|
// freely, subject to the following restrictions:
|
|
//
|
|
// 1. The origin of this software must not be misrepresented; you must not
|
|
// claim that you wrote the original software. If you use this software
|
|
// in a product, an acknowledgment in the product documentation would be
|
|
// appreciated but is not required.
|
|
// 2. Altered source versions must be plainly marked as such, and must not be
|
|
// misrepresented as being the original software.
|
|
// 3. This notice may not be removed or altered from any source distribution.
|
|
|
|
function adler32(adler, buf, len, pos) {
|
|
var s1 = (adler & 0xffff) |0,
|
|
s2 = ((adler >>> 16) & 0xffff) |0,
|
|
n = 0;
|
|
|
|
while (len !== 0) {
|
|
// Set limit ~ twice less than 5552, to keep
|
|
// s2 in 31-bits, because we force signed ints.
|
|
// in other case %= will fail.
|
|
n = len > 2000 ? 2000 : len;
|
|
len -= n;
|
|
|
|
do {
|
|
s1 = (s1 + buf[pos++]) |0;
|
|
s2 = (s2 + s1) |0;
|
|
} while (--n);
|
|
|
|
s1 %= 65521;
|
|
s2 %= 65521;
|
|
}
|
|
|
|
return (s1 | (s2 << 16)) |0;
|
|
}
|
|
|
|
|
|
module.exports = adler32;
|