Annotation of embedaddon/php/ext/bcmath/libbcmath/src/sub.c, revision 1.1.1.1
1.1 misho 1: /* sub.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. (COPYING.LIB)
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 <config.h>
33: #include <stdio.h>
34: #include <assert.h>
35: #include <stdlib.h>
36: #include <ctype.h>
37: #include <stdarg.h>
38: #include "bcmath.h"
39: #include "private.h"
40:
41:
42: /* Here is the full subtract routine that takes care of negative numbers.
43: N2 is subtracted from N1 and the result placed in RESULT. SCALE_MIN
44: is the minimum scale for the result. */
45:
46: void
47: bc_sub (n1, n2, result, scale_min)
48: bc_num n1, n2, *result;
49: int scale_min;
50: {
51: bc_num diff = NULL;
52: int cmp_res;
53: int res_scale;
54:
55: if (n1->n_sign != n2->n_sign)
56: {
57: diff = _bc_do_add (n1, n2, scale_min);
58: diff->n_sign = n1->n_sign;
59: }
60: else
61: {
62: /* subtraction must be done. */
63: /* Compare magnitudes. */
64: cmp_res = _bc_do_compare (n1, n2, FALSE, FALSE);
65: switch (cmp_res)
66: {
67: case -1:
68: /* n1 is less than n2, subtract n1 from n2. */
69: diff = _bc_do_sub (n2, n1, scale_min);
70: diff->n_sign = (n2->n_sign == PLUS ? MINUS : PLUS);
71: break;
72: case 0:
73: /* They are equal! return zero! */
74: res_scale = MAX (scale_min, MAX(n1->n_scale, n2->n_scale));
75: diff = bc_new_num (1, res_scale);
76: memset (diff->n_value, 0, res_scale+1);
77: break;
78: case 1:
79: /* n2 is less than n1, subtract n2 from n1. */
80: diff = _bc_do_sub (n1, n2, scale_min);
81: diff->n_sign = n1->n_sign;
82: break;
83: }
84: }
85:
86: /* Clean up and return. */
87: bc_free_num (result);
88: *result = diff;
89: }
90:
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