| 1 | /**
|
| 2 | * Created by clx on 2017/11/17.
|
| 3 | */
|
| 4 | /**
|
| 5 | * Calculate a 32 bit FNV-1a hash
|
| 6 | * Found here: https://gist.github.com/vaiorabbit/5657561
|
| 7 | * Ref.: http://isthe.com/chongo/tech/comp/fnv/
|
| 8 | *
|
| 9 | * @param {string} str the input value
|
| 10 | * @param {boolean} [asString=false] set to true to return the hash value as
|
| 11 | * 8-digit hex string instead of an integer
|
| 12 | * @param {integer} [seed] optionally pass the hash of the previous chunk
|
| 13 | * @returns {integer | string}
|
| 14 | */
|
| 15 | module.exports = function(str, asString, seed) {
|
| 16 | /*jshint bitwise:false */
|
| 17 | var i, l,
|
| 18 | hval = (seed === undefined) ? 0x811c9dc5 : seed;
|
| 19 |
|
| 20 | for (i = 0, l = str.length; i < l; i++) {
|
| 21 | hval ^= str.charCodeAt(i);
|
| 22 | hval += (hval << 1) + (hval << 4) + (hval << 7) + (hval << 8) + (hval << 24);
|
| 23 | }
|
| 24 | if( asString ){
|
| 25 | // Convert to 8 digit hex string
|
| 26 | return ("0000000" + (hval >>> 0).toString(16)).substr(-8);
|
| 27 | }
|
| 28 | return hval >>> 0;
|
| 29 | };
|