1 /* compare.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 <config.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <ctype.h>
36 #include <stdarg.h>
37 #include "bcmath.h"
38 #include "private.h"
39
40
41 /* Compare two bc numbers. Return value is 0 if equal, -1 if N1 is less
42 than N2 and +1 if N1 is greater than N2. If USE_SIGN is false, just
43 compare the magnitudes. */
44
45 int
_bc_do_compare(n1,n2,use_sign,ignore_last)46 _bc_do_compare (n1, n2, use_sign, ignore_last)
47 bc_num n1, n2;
48 int use_sign;
49 int ignore_last;
50 {
51 char *n1ptr, *n2ptr;
52 int count;
53
54 /* First, compare signs. */
55 if (use_sign && n1->n_sign != n2->n_sign)
56 {
57 if (n1->n_sign == PLUS)
58 return (1); /* Positive N1 > Negative N2 */
59 else
60 return (-1); /* Negative N1 < Positive N1 */
61 }
62
63 /* Now compare the magnitude. */
64 if (n1->n_len != n2->n_len)
65 {
66 if (n1->n_len > n2->n_len)
67 {
68 /* Magnitude of n1 > n2. */
69 if (!use_sign || n1->n_sign == PLUS)
70 return (1);
71 else
72 return (-1);
73 }
74 else
75 {
76 /* Magnitude of n1 < n2. */
77 if (!use_sign || n1->n_sign == PLUS)
78 return (-1);
79 else
80 return (1);
81 }
82 }
83
84 /* If we get here, they have the same number of integer digits.
85 check the integer part and the equal length part of the fraction. */
86 count = n1->n_len + MIN (n1->n_scale, n2->n_scale);
87 n1ptr = n1->n_value;
88 n2ptr = n2->n_value;
89
90 while ((count > 0) && (*n1ptr == *n2ptr))
91 {
92 n1ptr++;
93 n2ptr++;
94 count--;
95 }
96 if (ignore_last && count == 1 && n1->n_scale == n2->n_scale)
97 return (0);
98 if (count != 0)
99 {
100 if (*n1ptr > *n2ptr)
101 {
102 /* Magnitude of n1 > n2. */
103 if (!use_sign || n1->n_sign == PLUS)
104 return (1);
105 else
106 return (-1);
107 }
108 else
109 {
110 /* Magnitude of n1 < n2. */
111 if (!use_sign || n1->n_sign == PLUS)
112 return (-1);
113 else
114 return (1);
115 }
116 }
117
118 /* They are equal up to the last part of the equal part of the fraction. */
119 if (n1->n_scale != n2->n_scale)
120 {
121 if (n1->n_scale > n2->n_scale)
122 {
123 for (count = n1->n_scale-n2->n_scale; count>0; count--)
124 if (*n1ptr++ != 0)
125 {
126 /* Magnitude of n1 > n2. */
127 if (!use_sign || n1->n_sign == PLUS)
128 return (1);
129 else
130 return (-1);
131 }
132 }
133 else
134 {
135 for (count = n2->n_scale-n1->n_scale; count>0; count--)
136 if (*n2ptr++ != 0)
137 {
138 /* Magnitude of n1 < n2. */
139 if (!use_sign || n1->n_sign == PLUS)
140 return (-1);
141 else
142 return (1);
143 }
144 }
145 }
146
147 /* They must be equal! */
148 return (0);
149 }
150
151
152 /* This is the "user callable" routine to compare numbers N1 and N2. */
153
154 int
bc_compare(n1,n2)155 bc_compare (n1, n2)
156 bc_num n1, n2;
157 {
158 return _bc_do_compare (n1, n2, TRUE, FALSE);
159 }
160
