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Simplified Adler32() until deopt traces investigated - now fast enougth

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Vitaly Puzrin 2014-02-14 23:58:16 +04:00
parent c19d9ce8aa
commit aa4ddcac50
1 changed files with 19 additions and 46 deletions
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65
lib/zlib/adler32.js
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@ -1,55 +1,28 @@
'use strict'; 'use strict';
function adler32(adler, buf, len, start) // TODO: investigate why --trace_deopt shows something
{ // (though speed doesn't seems to reduce)
var BASE = 65521; /* largest prime smaller than 65536 */ //
var NMAX = 5552; function adler32(adler, buf, len, pos) {
var s1 = adler & 0xffff
, s2 = (adler >>> 16) & 0xffff
, n = 0;
var i = start; while (len !== 0) {
/* split Adler-32 into component sums */ n = len > 5552 ? 5552 : len;
var sum2 = (adler >> 16) & 0xffff; len -= n;
adler &= 0xffff;
/* in case user likes doing a byte at a time, keep it fast */ do {
if (len === 1) { s1 += buf[pos++];
adler += buf[0]; s2 += s1;
if (adler >= BASE) { } while (--n);
adler -= BASE;
} s1 %= 65521;
sum2 += adler; s2 %= 65521;
if (sum2 >= BASE) {
sum2 -= BASE;
}
return (adler | (sum2 << 16)) >>> 0;
} }
/* in case short lengths are provided, keep it somewhat fast */ return (s1 | (s2 << 16));
if (len < 16) {
for(i=0;i<len;i++) {
adler += buf[i];
sum2 += adler;
}
if (adler >= BASE) {
adler -= BASE;
}
sum2 %= BASE; /* only added so many BASE's */
return (adler | (sum2 << 16)) >>> 0;
}
while (len>0) {
var cursor = len > NMAX ? NMAX : len;
len -= cursor;
for(var j=0;j<cursor;j++) {
adler += buf[i++];
sum2 += adler;
}
adler %= BASE;
sum2 %= BASE;
}
/* return recombined sums */
return (adler | (sum2 << 16)) >>> 0;
} }
module.exports = adler32; module.exports = adler32;