contrib/ntp/libntp/hextoint.c

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