xref: /PHP-7.3/ext/bcmath/libbcmath/src/compare.c (revision 1c850bfc)
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
_bc_do_compare(n1,n2,use_sign,ignore_last)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
bc_compare(n1,n2)156 bc_compare (n1, n2)
157      bc_num n1, n2;
158 {
159   return _bc_do_compare (n1, n2, TRUE, FALSE);
160 }
161