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freebsd/contrib/ntp/libntp/atoint.c
1999-12-09 13:01:21 +00:00

51 lines
771 B
C

/*
* atoint - convert an ascii string to a signed long, with error checking
*/
#include <sys/types.h>
#include <ctype.h>
#include "ntp_types.h"
#include "ntp_stdlib.h"
int
atoint(
const char *str,
long *ival
)
{
register long u;
register const char *cp;
register int isneg;
register int oflow_digit;
cp = str;
if (*cp == '-') {
cp++;
isneg = 1;
oflow_digit = '8';
} else {
isneg = 0;
oflow_digit = '7';
}
if (*cp == '\0')
return 0;
u = 0;
while (*cp != '\0') {
if (!isdigit((int)*cp))
return 0;
if (u > 214748364 || (u == 214748364 && *cp > oflow_digit))
return 0; /* overflow */
u = (u << 3) + (u << 1);
u += *cp++ - '0'; /* ascii dependent */
}
if (isneg)
*ival = -u;
else
*ival = u;
return 1;
}