xntpd 3.3b from UDel

[unix-history] / contrib / xntpd / lib / atouint.c

/* atouint.c,v 3.1 1993/07/06 01:07:42 jbj Exp
* atouint - convert an ascii string to an unsigned long, with error checking
*/
#include <sys/types.h>
#include <ctype.h>

#include "ntp_types.h"

int
atouint(str, uval)
       const char *str;
       U_LONG *uval;
{
       register U_LONG u;
       register const char *cp;

       cp = str;
       if (*cp == '\0')
               return 0;

       u = 0;
       while (*cp != '\0') {
               if (!isdigit(*cp))
                       return 0;
               if (u > 429496729 || (u == 429496729 && *cp >= '6'))
                       return 0;       /* overflow */
               u = (u << 3) + (u << 1);
               u += *cp++ - '0';       /* ascii dependent */
       }

       *uval = u;
       return 1;
}