utils.js

/*

Copyright 2020 0KIMS association.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

*/

export function flatArray(a) {
    var res = [];
    fillArray(res, a);
    return res;

    function fillArray(res, a) {
        if (Array.isArray(a)) {
            for (let i=0; i<a.length; i++) {
                fillArray(res, a[i]);
            }
        } else {
            res.push(a);
        }
    }
}

// Ref https://github.com/iden3/circom/commit/ec6388cf6eb62463539cb4c40cc3ceae9826de19
export function normalize(n, prime) {
    let res = BigInt(n) % prime
    if (res < 0) res += prime
    return res
}

export function fnvHash(str) {
    const uint64_max = BigInt(2) ** BigInt(64);
    let hash = BigInt("0xCBF29CE484222325");
    for (var i = 0; i < str.length; i++) {
    hash ^= BigInt(str[i].charCodeAt());
    hash *= BigInt(0x100000001B3);
    hash %= uint64_max;
    }
    let shash = hash.toString(16);
    let n = 16 - shash.length;
    shash = '0'.repeat(n).concat(shash);
    return shash;
}

// Note that this pads zeros
export function toArray32(s,size) {
    const res = []; //new Uint32Array(size); //has no unshift
    let rem = BigInt(s);
    const radix = BigInt(0x100000000);
    while (rem) {
        res.unshift( Number(rem % radix));
        rem = rem / radix;
    }
    if (size) {
    var i = size - res.length;
    while (i>0) {
        res.unshift(0);
        i--;
    }
    }
    return res;
}