Building off of this question How to get this PRNG to generate numbers within the range? , I am making it support BigInt (big values) in JavaScript, and I think I have it right (please correct me if I did it incorrectly):
const fetch = (x, o) => {
if (x >= o) {
return x
} else {
const v = (x * x) % o
return (x <= (o / 2n)) ? v : o - v
}
}
const fetchLarge = (x) => fetch(x, 43214321432143214321432143214321432143214321n)
// the last number can be anything.
const buildLarge = (x, o) => fetchLarge((fetchLarge(x) + o) % BigInt(Math.pow(32, 31)) ^ 101010101010104321432143214321n)
const j = 432143213214321432143214321432143214321n; // If you don't want duplicates, either i or j should stay fixed
let i = 1n
let invalid = [];
let valid = new Set;
while (i) {
let x = buildLarge(i, j);
if (valid.has(x)) {
invalid.push([i, j, x]);
} else {
valid.add(x);
}
console.log(x)
i++;
}
console.log("invalid:", invalid);
console.log("valid:", [...valid]);
console.log("count of valid:", valid.size);
Sidenote: There should never be an invalid value.
But the main question is, given a value of x such as 40531205068036774067539981357810868028938588n, how can you divide it into an array of 5-bit values (array of integers between 0-31)?
Is it just as simple as doing x.toString(32) and then converting those letters to indices or something? Not sure if I'm doing this correctly.
To create an array with numbers between 0-31 you can just divide and collect the remainders (which you would then convert to standard number):
function createArray(n, mod=32n) {
if (!n) return [0];
let arr = [];
while (n) {
arr.push(Number(n % mod));
n /= mod;
}
return arr;
}
let result = createArray(40531205068036774067539981357810868028938588n);
console.log(result);