KasmVNC/kasmweb/vendor/pako/lib/zlib/adler32.js
2020-09-20 12:16:44 +00:00

28 lines
666 B
JavaScript

// Note: adler32 takes 12% for level 0 and 2% for level 6.
// It doesn't worth to make additional optimizationa as in original.
// Small size is preferable.
export default 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;
}