src/api/arithmetic/gcd/euclidean_algorithm.js

import _trim_positive from '../../../core/convert/_trim_positive.js';
import _alloc from '../../../core/array/_alloc.js';
import _copy from '../../../core/array/_copy.js';

import _cmp_n from '../../../core/compare/_cmp_n.js';
import _euclidean_algorithm_loop from '../../../core/arithmetic/gcd/_euclidean_algorithm_loop.js';

/**
 * No constraints on the input.
 *
 * @param {Number} r The radix.
 * @param {Array} a First input number <code>a>b</code>.
 * @param {Number} ai <code>a</code> left bound.
 * @param {Number} aj <code>a</code> right bound.
 * @param {Array} b Second input number <code>b<a</code>.
 * @param {Number} bi <code>b</code> left bound.
 * @param {Number} bj <code>b</code> right bound.
 * @returns {Array} The array containing the gcd of A and B (one of A and B).
 * Return as [ d , di , dj ], where d is the array and di and dj are its left
 * and right bounds.
 */
export default function euclidean_algorithm(r, a, ai, aj, b, bi, bj) {
	const _ai = _trim_positive(a, ai, aj);
	const _bi = _trim_positive(b, bi, bj);
	const m = aj - _ai;
	const n = bj - _bi;

	const R0 = _alloc(m);
	_copy(a, _ai, aj, R0, 0);
	const R1 = _alloc(n);
	_copy(b, _bi, bj, R1, 0);

	return m > n || (m === n && _cmp_n(R0, 0, m, R1, 0) >= 0)
		? _euclidean_algorithm_loop(r, R0, 0, m, R1, 0, n)
		: _euclidean_algorithm_loop(r, R1, 0, n, R0, 0, m);
}