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. (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 /* Compare two bc numbers. Return value is 0 if equal, -1 if N1 is less
43 than N2 and +1 if N1 is greater than N2. If USE_SIGN is false, just
44 compare the magnitudes. */
45
46 int
47 _bc_do_compare (n1, n2, use_sign, ignore_last)
48 bc_num n1, n2;
49 int use_sign;
50 int ignore_last;
51 {
52 char *n1ptr, *n2ptr;
53 int count;
54
55 /* First, compare signs. */
56 if (use_sign && n1->n_sign != n2->n_sign)
57 {
58 if (n1->n_sign == PLUS)
59 return (1); /* Positive N1 > Negative N2 */
60 else
61 return (-1); /* Negative N1 < Positive N1 */
62 }
63
64 /* Now compare the magnitude. */
65 if (n1->n_len != n2->n_len)
66 {
67 if (n1->n_len > n2->n_len)
68 {
69 /* Magnitude of n1 > n2. */
70 if (!use_sign || n1->n_sign == PLUS)
71 return (1);
72 else
73 return (-1);
74 }
75 else
76 {
77 /* Magnitude of n1 < n2. */
78 if (!use_sign || n1->n_sign == PLUS)
79 return (-1);
80 else
81 return (1);
82 }
83 }
84
85 /* If we get here, they have the same number of integer digits.
86 check the integer part and the equal length part of the fraction. */
87 count = n1->n_len + MIN (n1->n_scale, n2->n_scale);
88 n1ptr = n1->n_value;
89 n2ptr = n2->n_value;
90
91 while ((count > 0) && (*n1ptr == *n2ptr))
92 {
93 n1ptr++;
94 n2ptr++;
95 count--;
96 }
97 if (ignore_last && count == 1 && n1->n_scale == n2->n_scale)
98 return (0);
99 if (count != 0)
100 {
101 if (*n1ptr > *n2ptr)
102 {
103 /* Magnitude of n1 > n2. */
104 if (!use_sign || n1->n_sign == PLUS)
105 return (1);
106 else
107 return (-1);
108 }
109 else
110 {
111 /* Magnitude of n1 < n2. */
112 if (!use_sign || n1->n_sign == PLUS)
113 return (-1);
114 else
115 return (1);
116 }
117 }
118
119 /* They are equal up to the last part of the equal part of the fraction. */
120 if (n1->n_scale != n2->n_scale)
121 {
122 if (n1->n_scale > n2->n_scale)
123 {
124 for (count = n1->n_scale-n2->n_scale; count>0; count--)
125 if (*n1ptr++ != 0)
126 {
127 /* Magnitude of n1 > n2. */
128 if (!use_sign || n1->n_sign == PLUS)
129 return (1);
130 else
131 return (-1);
132 }
133 }
134 else
135 {
136 for (count = n2->n_scale-n1->n_scale; count>0; count--)
137 if (*n2ptr++ != 0)
138 {
139 /* Magnitude of n1 < n2. */
140 if (!use_sign || n1->n_sign == PLUS)
141 return (-1);
142 else
143 return (1);
144 }
145 }
146 }
147
148 /* They must be equal! */
149 return (0);
150 }
151
152
153 /* This is the "user callable" routine to compare numbers N1 and N2. */
154
155 int
156 bc_compare (n1, n2)
157 bc_num n1, n2;
158 {
159 return _bc_do_compare (n1, n2, TRUE, FALSE);
160 }
161