/*
 * lib/decmath.js - Fast and light decimal math
 *
 * @licstart  The following is the entire license notice for the
 * JavaScript code in this file.
 *
 * Copyright (C) 2017  Libiquity LLC
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * As additional permission under GNU GPL version 3 section 7, you
 * may distribute non-source (e.g. minimized or compacted) forms of
 * this program without the copy of the GNU GPL normally required by
 * section 4, provided you include this license notice and a URL
 * through which recipients can access the Corresponding Source.
 *
 * @licend  The above is the entire license notice
 * for the JavaScript code in this file.
 */

"use strict";

function dadd(a, b)
{
	a = a.toString().split(".", 2);
	b = b.toString().split(".", 2);
	if (typeof a[1] == "undefined") a[1] = "";
	if (typeof b[1] == "undefined") b[1] = "";
	var ce;
	if (a[1].length == b[1].length) {
		ce = a[1].length;
	} else if (a[1].length < b[1].length) {
		a[1] += Array(b[1].length - a[1].length + 1).join("0");
		ce = b[1].length;
	} else {
		b[1] += Array(a[1].length - b[1].length + 1).join("0");
		ce = a[1].length;
	}
	var as = a[0] + a[1];
	var bs = b[0] + b[1];
	var cs = (parseInt(as, 10) + parseInt(bs, 10)).toString();
	var pad = ce - cs.length;
	if (pad > 0) cs = (Array(pad + 1).join("0") + cs).toString();
	return cs.substr(0, cs.length - ce) + "." + cs.substr(cs.length - ce);
}

function dmul(a, b)
{
	a = a.toString().split(".", 2);
	b = b.toString().split(".", 2);
	if (typeof a[1] == "undefined") a[1] = "";
	if (typeof b[1] == "undefined") b[1] = "";
	var as = a[0] + a[1];
	var bs = b[0] + b[1];
	var cs = (parseInt(as, 10) * parseInt(bs, 10)).toString();
	var ce = a[1].length + b[1].length;
	var pad = ce - cs.length;
	if (pad > 0) cs = (Array(pad + 1).join("0") + cs).toString();
	return cs.substr(0, cs.length - ce) + "." + cs.substr(cs.length - ce);
}

function drhtz(a, p)
{
	a = a.toString().split(".", 2);
	if (a.length == 1) return null;
	var ad = a[1].substr(p);
	a[1] = a[1].substr(0, p);
	var as = a.join("");
	if (as.charAt(0) != "-") {
		if (parseInt(ad, 10) > 5 * Math.pow(10, ad.length - 1)) {
			as = (parseInt(as) + 1).toString();
		}
	} else {
		if (parseInt(ad, 10) > 5 * Math.pow(10, ad.length - 1)) {
			as = (parseInt(as) - 1).toString();
		}
	}
	var pad = p - as.length;
	if (pad > 0) as = (Array(pad + 1).join("0") + as).toString();
	return as.substr(0, as.length - p) + "." + as.substr(as.length - p);
}

function drhfz(a, p)
{
	a = a.toString().split(".", 2);
	if (a.length == 1) return null;
	var ad = a[1].substr(p);
	a[1] = a[1].substr(0, p);
	var as = a.join("");
	if (as.charAt(0) != "-") {
		if (parseInt(ad, 10) >= 5 * Math.pow(10, ad.length - 1)) {
			as = (parseInt(as) + 1).toString();
		}
	} else {
		if (parseInt(ad, 10) >= 5 * Math.pow(10, ad.length - 1)) {
			as = (parseInt(as) - 1).toString();
		}
	}
	var pad = p - as.length;
	if (pad > 0) as = (Array(pad + 1).join("0") + as).toString();
	return as.substr(0, as.length - p) + "." + as.substr(as.length - p);
}

function dfmt(a, p)
{
	a = a.toString().split(".", 2);
	if (a.length == 1) return null;
	if (a[0] == "") a[0] = "0";
	if (a[0] == "-") a[0] = "-0";
	if (a[1].length < p) a[1] += Array(p - a[1].length + 1).join("0");
	return a.join(".");
}

if (typeof global != "undefined") {
	global.dadd = dadd;
	global.dmul = dmul;
	global.drhtz = drhtz;
	global.drhfz = drhfz;
	global.dfmt = dfmt;
}