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1.1 misho 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: