@woosh/meep-engine/src/core/math/isqrt.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 * Integer square root
 *
 * @author Jim Ulery (attributed on hextreme)
 * @see https://en.wikipedia.org/wiki/Integer_square_root
 * @see https://git.immc.ucl.ac.be/hextreme/hxt_seqdel/-/blob/master/src/hxt_tetrahedra.c#L54
 *
 * @param {number} input
 * @returns {number}
 */
export function isqrt(input) {
    let temp;

    let g = 0;
    let b = 0x8000;
    let bshft = 15;

    let val = input;

    do {
        if (val >= (temp = (((g << 1) + b) << bshft--))) {
            g += b;
            val -= temp;
        }
    } while (b >>= 1);

    return g;
}