46 lines
1.0 KiB
JavaScript
46 lines
1.0 KiB
JavaScript
|
/*
|
||
|
|
MIT License http://www.opensource.org/licenses/mit-license.php
|
||
|
|
Author Tobias Koppers @sokra
|
||
|
|
*/
|
||
|
|
|
||
|
|
"use strict";
|
||
|
|
|
||
|
|
const SAFE_LIMIT = 0x80000000;
|
||
|
|
const SAFE_PART = SAFE_LIMIT - 1;
|
||
|
|
const COUNT = 4;
|
||
|
|
const arr = [0, 0, 0, 0, 0];
|
||
|
|
const primes = [3, 7, 17, 19];
|
||
|
|
|
||
|
|
module.exports = (str, range) => {
|
||
|
|
arr.fill(0);
|
||
|
|
for (let i = 0; i < str.length; i++) {
|
||
|
|
const c = str.charCodeAt(i);
|
||
|
|
for (let j = 0; j < COUNT; j++) {
|
||
|
|
const p = (j + COUNT - 1) % COUNT;
|
||
|
|
arr[j] = (arr[j] + c * primes[j] + arr[p]) & SAFE_PART;
|
||
|
|
}
|
||
|
|
for (let j = 0; j < COUNT; j++) {
|
||
|
|
const q = arr[j] % COUNT;
|
||
|
|
arr[j] = arr[j] ^ (arr[q] >> 1);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
if (range <= SAFE_PART) {
|
||
|
|
let sum = 0;
|
||
|
|
for (let j = 0; j < COUNT; j++) {
|
||
|
|
sum = (sum + arr[j]) % range;
|
||
|
|
}
|
||
|
|
return sum;
|
||
|
|
} else {
|
||
|
|
let sum1 = 0;
|
||
|
|
let sum2 = 0;
|
||
|
|
const rangeExt = Math.floor(range / SAFE_LIMIT);
|
||
|
|
for (let j = 0; j < COUNT; j += 2) {
|
||
|
|
sum1 = (sum1 + arr[j]) & SAFE_PART;
|
||
|
|
}
|
||
|
|
for (let j = 1; j < COUNT; j += 2) {
|
||
|
|
sum2 = (sum2 + arr[j]) % rangeExt;
|
||
|
|
}
|
||
|
|
return (sum2 * SAFE_LIMIT + sum1) % range;
|
||
|
|
}
|
||
|
|
};
|