1 /* divmod.c: bcmath library file. */
2 /*
3 Copyright (C) 1991, 1992, 1993, 1994, 1997 Free Software Foundation, Inc.
4 Copyright (C) 2000 Philip A. Nelson
5
6 This library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2 of the License, or (at your option) any later version.
10
11 This library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details. (LICENSE)
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with this library; if not, write to:
18
19 The Free Software Foundation, Inc.
20 59 Temple Place, Suite 330
21 Boston, MA 02111-1307 USA.
22
23 You may contact the author by:
24 e-mail: philnelson@acm.org
25 us-mail: Philip A. Nelson
26 Computer Science Department, 9062
27 Western Washington University
28 Bellingham, WA 98226-9062
29
30 *************************************************************************/
31
32 #include "bcmath.h"
33 #include <stdbool.h>
34 #include <stddef.h>
35
36
37 /* Division *and* modulo for numbers. This computes both NUM1 / NUM2 and
38 NUM1 % NUM2 and puts the results in QUOT and REM, except that if QUOT
39 is NULL then that store will be omitted.
40 false is returned if divisor is 0.
41 true otherwise for success.
42 */
43
bc_divmod(bc_num num1,bc_num num2,bc_num * quot,bc_num * rem,size_t scale)44 bool bc_divmod(bc_num num1, bc_num num2, bc_num *quot, bc_num *rem, size_t scale)
45 {
46 bc_num quotient = NULL;
47 bc_num temp;
48 size_t rscale;
49
50 /* Cannot divide/mod by 0. */
51 if (bc_is_zero(num2)) {
52 return false;
53 }
54
55 /* Calculate final scale. */
56 rscale = MAX (num1->n_scale, num2->n_scale + scale);
57 bc_init_num(&temp);
58
59 /* Calculate it. */
60 bc_divide(num1, num2, &temp, 0);
61 if (quot) {
62 quotient = bc_copy_num(temp);
63 }
64 bc_multiply_ex(temp, num2, &temp, rscale);
65 bc_sub_ex(num1, temp, rem, rscale);
66 bc_free_num (&temp);
67
68 if (quot) {
69 bc_free_num (quot);
70 *quot = quotient;
71 }
72
73 /* The value of rscale changes during processing. Here we use the value of scale. It's not a typo. */
74 (*rem)->n_scale = MIN(scale, (*rem)->n_scale);
75 if (bc_is_zero(*rem)) {
76 (*rem)->n_sign = PLUS;
77 }
78
79 return true;
80 }
81
82
83 /* Modulo for numbers. This computes NUM1 % NUM2 and puts the
84 result in RESULT. */
85
bc_modulo(bc_num num1,bc_num num2,bc_num * result,size_t scale)86 bool bc_modulo(bc_num num1, bc_num num2, bc_num *result, size_t scale)
87 {
88 return bc_divmod(num1, num2, NULL, result, scale);
89 }
90
