aureooms/js-integer-little-endian

/**
 * Subtracts two big endian arrays, k >= i >= j
 * wraps
 *
 * @param {int} r base (radix)
 * @param {array} a first operand
 * @param {int} ai a left
 * @param {int} aj a right
 * @param {array} b second operand
 * @param {int} bi b left
 * @param {int} bj b right
 * @param {array} c result, must be 0 initialized
 * @param {int} ci c left
 * @param {int} cj c right
 */

export const _sub = function ( r , a, ai, aj, b, bi, bj, c, ci, cj){
    var T, C = 0;

    while(--bj >= bi){
        --aj; --cj;
        T = C;
        C = a[aj] < b[bj] + T;
        c[cj] = a[aj] - b[bj] + (C*r - T);
    }

    while(--aj >= ai){
        --cj;
        T = C;
        C = a[aj] < T;
        c[cj] = a[aj] + (C*r - T);
    }

    if(C){
        while(--cj >= ci){
            c[cj] = r - 1;
        }
    }

};