lapo.it
1// Big integer base-10 printing library
2// Copyright (c) 2014-2018 Lapo Luchini <lapo@lapo.it>
3
4// Permission to use, copy, modify, and/or distribute this software for any
5// purpose with or without fee is hereby granted, provided that the above
6// copyright notice and this permission notice appear in all copies.
7//
8// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15
16(function () {
17"use strict";
18
19var max = 10000000000000; // biggest 10^n integer that can still fit 2^53 when multiplied by 256
20
21function Int10(value) {
22 this.buf = [+value || 0];
23}
24
25Int10.prototype.mulAdd = function (m, c) {
26 // assert(m <= 256)
27 var b = this.buf,
28 l = b.length,
29 i, t;
30 for (i = 0; i < l; ++i) {
31 t = b[i] * m + c;
32 if (t < max)
33 c = 0;
34 else {
35 c = 0|(t / max);
36 t -= c * max;
37 }
38 b[i] = t;
39 }
40 if (c > 0)
41 b[i] = c;
42};
43
44Int10.prototype.sub = function (c) {
45 // assert(m <= 256)
46 var b = this.buf,
47 l = b.length,
48 i, t;
49 for (i = 0; i < l; ++i) {
50 t = b[i] - c;
51 if (t < 0) {
52 t += max;
53 c = 1;
54 } else
55 c = 0;
56 b[i] = t;
57 }
58 while (b[b.length - 1] === 0)
59 b.pop();
60};
61
62Int10.prototype.toString = function (base) {
63 if ((base || 10) != 10)
64 throw 'only base 10 is supported';
65 var b = this.buf,
66 s = b[b.length - 1].toString();
67 for (var i = b.length - 2; i >= 0; --i)
68 s += (max + b[i]).toString().substring(1);
69 return s;
70};
71
72Int10.prototype.valueOf = function () {
73 var b = this.buf,
74 v = 0;
75 for (var i = b.length - 1; i >= 0; --i)
76 v = v * max + b[i];
77 return v;
78};
79
80Int10.prototype.simplify = function () {
81 var b = this.buf;
82 return (b.length == 1) ? b[0] : this;
83};
84
85// export globals
86if (typeof module !== 'undefined') { module.exports = Int10; } else { window.Int10 = Int10; }
87})();