1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
|
/* Compare numeric strings. This is an internal include file.
Copyright (C) 1988, 1991, 1992, 1993, 1995, 1996, 1998, 1999, 2000,
2003, 2004, 2005 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Written by Mike Haertel. */
#include "strnumcmp.h"
#include <stddef.h>
#define NEGATION_SIGN '-'
#define NUMERIC_ZERO '0'
/* ISDIGIT differs from isdigit, as follows:
- Its arg may be any int or unsigned int; it need not be an unsigned char.
- It's guaranteed to evaluate its argument exactly once.
- It's typically faster.
POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to
ISDIGIT_LOCALE unless it's important to use the locale's definition
of `digit' even when the host does not conform to POSIX. */
#define ISDIGIT(c) ((unsigned int) (c) - '0' <= 9)
/* Compare strings A and B containing decimal fractions < 1.
DECIMAL_POINT is the decimal point. Each string
should begin with a decimal point followed immediately by the digits
of the fraction. Strings not of this form are treated as zero. */
/* The goal here, is to take two numbers a and b... compare these
in parallel. Instead of converting each, and then comparing the
outcome. Most likely stopping the comparison before the conversion
is complete. The algorithm used, in the old "sort" utility:
Algorithm: fraccompare
Action : compare two decimal fractions
accepts : char *a, char *b
returns : -1 if a<b, 0 if a=b, 1 if a>b.
implement:
if *a == decimal_point AND *b == decimal_point
find first character different in a and b.
if both are digits, return the difference *a - *b.
if *a is a digit
skip past zeros
if digit return 1, else 0
if *b is a digit
skip past zeros
if digit return -1, else 0
if *a is a decimal_point
skip past decimal_point and zeros
if digit return 1, else 0
if *b is a decimal_point
skip past decimal_point and zeros
if digit return -1, else 0
return 0 */
static inline int
fraccompare (char const *a, char const *b, char decimal_point)
{
if (*a == decimal_point && *b == decimal_point)
{
while (*++a == *++b)
if (! ISDIGIT (*a))
return 0;
if (ISDIGIT (*a) && ISDIGIT (*b))
return *a - *b;
if (ISDIGIT (*a))
goto a_trailing_nonzero;
if (ISDIGIT (*b))
goto b_trailing_nonzero;
return 0;
}
else if (*a++ == decimal_point)
{
a_trailing_nonzero:
while (*a == NUMERIC_ZERO)
a++;
return ISDIGIT (*a);
}
else if (*b++ == decimal_point)
{
b_trailing_nonzero:
while (*b == NUMERIC_ZERO)
b++;
return - ISDIGIT (*b);
}
return 0;
}
/* Compare strings A and B as numbers without explicitly converting
them to machine numbers, to avoid overflow problems and perhaps
improve performance. DECIMAL_POINT is the decimal point and
THOUSANDS_SEP the thousands separator. A DECIMAL_POINT of -1
causes comparisons to act as if there is no decimal point
character, and likewise for THOUSANDS_SEP. */
static inline int
numcompare (char const *a, char const *b,
int decimal_point, int thousands_sep)
{
unsigned char tmpa = *a;
unsigned char tmpb = *b;
int tmp;
size_t log_a;
size_t log_b;
if (tmpa == NEGATION_SIGN)
{
do
tmpa = *++a;
while (tmpa == NUMERIC_ZERO || tmpa == thousands_sep);
if (tmpb != NEGATION_SIGN)
{
if (tmpa == decimal_point)
do
tmpa = *++a;
while (tmpa == NUMERIC_ZERO);
if (ISDIGIT (tmpa))
return -1;
while (tmpb == NUMERIC_ZERO || tmpb == thousands_sep)
tmpb = *++b;
if (tmpb == decimal_point)
do
tmpb = *++b;
while (tmpb == NUMERIC_ZERO);
return - ISDIGIT (tmpb);
}
do
tmpb = *++b;
while (tmpb == NUMERIC_ZERO || tmpb == thousands_sep);
while (tmpa == tmpb && ISDIGIT (tmpa))
{
do
tmpa = *++a;
while (tmpa == thousands_sep);
do
tmpb = *++b;
while (tmpb == thousands_sep);
}
if ((tmpa == decimal_point && !ISDIGIT (tmpb))
|| (tmpb == decimal_point && !ISDIGIT (tmpa)))
return fraccompare (b, a, decimal_point);
tmp = tmpb - tmpa;
for (log_a = 0; ISDIGIT (tmpa); ++log_a)
do
tmpa = *++a;
while (tmpa == thousands_sep);
for (log_b = 0; ISDIGIT (tmpb); ++log_b)
do
tmpb = *++b;
while (tmpb == thousands_sep);
if (log_a != log_b)
return log_a < log_b ? 1 : -1;
if (!log_a)
return 0;
return tmp;
}
else if (tmpb == NEGATION_SIGN)
{
do
tmpb = *++b;
while (tmpb == NUMERIC_ZERO || tmpb == thousands_sep);
if (tmpb == decimal_point)
do
tmpb = *++b;
while (tmpb == NUMERIC_ZERO);
if (ISDIGIT (tmpb))
return 1;
while (tmpa == NUMERIC_ZERO || tmpa == thousands_sep)
tmpa = *++a;
if (tmpa == decimal_point)
do
tmpa = *++a;
while (tmpa == NUMERIC_ZERO);
return ISDIGIT (tmpa);
}
else
{
while (tmpa == NUMERIC_ZERO || tmpa == thousands_sep)
tmpa = *++a;
while (tmpb == NUMERIC_ZERO || tmpb == thousands_sep)
tmpb = *++b;
while (tmpa == tmpb && ISDIGIT (tmpa))
{
do
tmpa = *++a;
while (tmpa == thousands_sep);
do
tmpb = *++b;
while (tmpb == thousands_sep);
}
if ((tmpa == decimal_point && !ISDIGIT (tmpb))
|| (tmpb == decimal_point && !ISDIGIT (tmpa)))
return fraccompare (a, b, decimal_point);
tmp = tmpa - tmpb;
for (log_a = 0; ISDIGIT (tmpa); ++log_a)
do
tmpa = *++a;
while (tmpa == thousands_sep);
for (log_b = 0; ISDIGIT (tmpb); ++log_b)
do
tmpb = *++b;
while (tmpb == thousands_sep);
if (log_a != log_b)
return log_a < log_b ? -1 : 1;
if (!log_a)
return 0;
return tmp;
}
}
|
