phpjs/workbench/bc/bcmath-js/src/libbcmath.add.js

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/**
 * Base add function
 *
 //  Here is the full add routine that takes care of negative numbers.
 //  N1 is added to N2 and the result placed into RESULT.  SCALE_MIN
 //  is the minimum scale for the result.
 *
 * @param bc_num n1
 * @param bc_num n2
 * @pram int scale_min
 * @return bc_num
 */
libbcmath.bc_add = function(n1, n2, scale_min) {
  var sum, cmp_res, res_scale;

  if (n1.n_sign === n2.n_sign) {
    sum = libbcmath._bc_do_add(n1, n2, scale_min);
    sum.n_sign = n1.n_sign;
  } else {
    /* subtraction must be done. */
    cmp_res = libbcmath._bc_do_compare(n1, n2, false, false); /* Compare magnitudes. */
    switch (cmp_res) {
      case -1:
        /* n1 is less than n2, subtract n1 from n2. */
        sum = libbcmath._bc_do_sub(n2, n1, scale_min);
        sum.n_sign = n2.n_sign;
        break;

      case 0:
        /* They are equal! return zero with the correct scale! */
        res_scale = libbcmath.MAX(scale_min, libbcmath.MAX(n1.n_scale, n2.n_scale));
        sum = libbcmath.bc_new_num(1, res_scale);
        libbcmath.memset(sum.n_value, 0, 0, res_scale + 1);
        break;

      case 1:
        /* n2 is less than n1, subtract n2 from n1. */
        sum = libbcmath._bc_do_sub(n1, n2, scale_min);
        sum.n_sign = n1.n_sign;
    }
  }
  return sum;
};