dist/ntp/libntp/hextoint.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * hextoint - convert an ascii string in hex to an unsigned
   5  *            long, with error checking
   6  */
   7 #include <ctype.h>
   8
   9 #include "ntp_stdlib.h"
  10
  11 int
  12 hextoint(
  13         const char *str,
  14         u_long *ival
  15         )
  16 {
  17         register u_long u;
  18         register const char *cp;
  19
  20         cp = str;
  21
  22         if (*cp == '\0')
  23             return 0;
  24
  25         u = 0;
  26         while (*cp != '\0') {
  27                 if (!isxdigit((int)*cp))
  28                     return 0;
  29                 if (u >= 0x10000000)
  30                     return 0;   /* overflow */
  31                 u <<= 4;
  32                 if (*cp <= '9')         /* very ascii dependent */
  33                     u += *cp++ - '0';
  34                 else if (*cp >= 'a')
  35                     u += *cp++ - 'a' + 10;
  36                 else
  37                     u += *cp++ - 'A' + 10;
  38         }
  39         *ival = u;
  40         return 1;
  41 }