crypto-sieve/dist/index.js

Low memory-usage implementation of a Sieve of Eratosthenes.

/* HELPERS */
const { floor } = Math;
/* MAIN */
//TODO: Use windowing for the buffer, allocating a fixed-size buffer that gets repopulated when needed
const sieve = (limit) => {
    return [...sieve.iterator(limit)];
};
/* UTILITIES */
sieve.iterator = function* (limit) {
    if (limit < 2)
        return;
    const buffer = new Uint8Array(Math.ceil(limit / 2 / 8)); // 1 bit per odd number, 0 = prime, 1 = not prime
    yield 2; // The first prime, and the only even prime
    for (let i = 1, l = Math.ceil(limit / 2); i < l; i++) {
        const bufferIndex = floor(i / 8);
        const byteIndex = i % 8;
        if ((buffer[bufferIndex] & (1 << byteIndex)) === 0) { // Is prime
            const prime = (i << 1) + 1;
            yield prime;
            for (let j = i + prime; j < l; j += prime) {
                const bufferIndex = floor(j / 8);
                const byteIndex = j % 8;
                buffer[bufferIndex] |= (1 << byteIndex); // Is not prime
            }
        }
    }
};
/* EXPORT */
export default sieve;