| 'use strict'; |
| |
| // 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. |
| |
| 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; |