dist/ntp/libntp/hextolfp.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * hextolfp - convert an ascii hex string to an l_fp number
   5  */
   6 #include <stdio.h>
   7 #include <ctype.h>
   8
   9 #include "ntp_fp.h"
  10 #include "ntp_string.h"
  11 #include "ntp_stdlib.h"
  12
  13 int
  14 hextolfp(
  15         const char *str,
  16         l_fp *lfp
  17         )
  18 {
  19         register const char *cp;
  20         register const char *cpstart;
  21         register u_long dec_i;
  22         register u_long dec_f;
  23         char *ind = NULL;
  24         static const char *digits = "0123456789abcdefABCDEF";
  25
  26         dec_i = dec_f = 0;
  27         cp = str;
  28
  29         /*
  30          * We understand numbers of the form:
  31          *
  32          * [spaces]8_hex_digits[.]8_hex_digits[spaces|\n|\0]
  33          */
  34         while (isspace((int)*cp))
  35             cp++;
  36
  37         cpstart = cp;
  38         while (*cp != '\0' && (cp - cpstart) < 8 &&
  39                (ind = strchr(digits, *cp)) != NULL) {
  40                 dec_i = dec_i << 4;     /* multiply by 16 */
  41                 dec_i += ((ind - digits) > 15) ? (ind - digits) - 6
  42                         : (ind - digits);
  43                 cp++;
  44         }
  45
  46         if ((cp - cpstart) < 8 || ind == NULL)
  47             return 0;
  48         if (*cp == '.')
  49             cp++;
  50
  51         cpstart = cp;
  52         while (*cp != '\0' && (cp - cpstart) < 8 &&
  53                (ind = strchr(digits, *cp)) != NULL) {
  54                 dec_f = dec_f << 4;     /* multiply by 16 */
  55                 dec_f += ((ind - digits) > 15) ? (ind - digits) - 6
  56                         : (ind - digits);
  57                 cp++;
  58         }
  59
  60         if ((cp - cpstart) < 8 || ind == NULL)
  61             return 0;
  62
  63         if (*cp != '\0' && !isspace((int)*cp))
  64             return 0;
  65
  66         lfp->l_ui = dec_i;
  67         lfp->l_uf = dec_f;
  68         return 1;
  69 }