Copyright (C) 1988, 1991-1993, 1995-1996, 1998-2000, 2003-2006, 2009-2010
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 3 of the License, 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, see <http://www.gnu.org/licenses/>. */
#ifndef STRNUMCMP_IN_H
# define STRNUMCMP_IN_H 1
# include "strnumcmp.h"
# include <stddef.h>
# define NEGATION_SIGN '-'
# define NUMERIC_ZERO '0'
- Its arg may be any int or unsigned int; it need not be an unsigned char
or EOF.
- It's typically faster.
POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to
isdigit 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)
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. */
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;
}
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;
}
}
#endif
