1 /*
2 * This file is part of the MicroPython project, http://micropython.org/
3 *
4 * The MIT License (MIT)
5 *
6 * Copyright (c) 2013, 2014 Damien P. George
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24 * THE SOFTWARE.
25 */
26
27 #include "py/smallint.h"
28
mp_small_int_mul_overflow(mp_int_t x,mp_int_t y)29 bool mp_small_int_mul_overflow(mp_int_t x, mp_int_t y) {
30 // Check for multiply overflow; see CERT INT32-C
31 if (x > 0) { // x is positive
32 if (y > 0) { // x and y are positive
33 if (x > (MP_SMALL_INT_MAX / y)) {
34 return true;
35 }
36 } else { // x positive, y nonpositive
37 if (y < (MP_SMALL_INT_MIN / x)) {
38 return true;
39 }
40 } // x positive, y nonpositive
41 } else { // x is nonpositive
42 if (y > 0) { // x is nonpositive, y is positive
43 if (x < (MP_SMALL_INT_MIN / y)) {
44 return true;
45 }
46 } else { // x and y are nonpositive
47 if (x != 0 && y < (MP_SMALL_INT_MAX / x)) {
48 return true;
49 }
50 } // End if x and y are nonpositive
51 } // End if x is nonpositive
52 return false;
53 }
54
mp_small_int_modulo(mp_int_t dividend,mp_int_t divisor)55 mp_int_t mp_small_int_modulo(mp_int_t dividend, mp_int_t divisor) {
56 // Python specs require that mod has same sign as second operand
57 dividend %= divisor;
58 if ((dividend < 0 && divisor > 0) || (dividend > 0 && divisor < 0)) {
59 dividend += divisor;
60 }
61 return dividend;
62 }
63
mp_small_int_floor_divide(mp_int_t num,mp_int_t denom)64 mp_int_t mp_small_int_floor_divide(mp_int_t num, mp_int_t denom) {
65 if (num >= 0) {
66 if (denom < 0) {
67 num += -denom - 1;
68 }
69 } else {
70 if (denom >= 0) {
71 num += -denom + 1;
72 }
73 }
74 return num / denom;
75 }
76