dist/ntp/libntp/mstolfp.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * mstolfp - convert an ascii string in milliseconds to an l_fp number
   5  */
   6 #include <stdio.h>
   7 #include <ctype.h>
   8
   9 #include "ntp_fp.h"
  10 #include "ntp_stdlib.h"
  11
  12 int
  13 mstolfp(
  14         const char *str,
  15         l_fp *lfp
  16         )
  17 {
  18         register const char *cp;
  19         register char *bp;
  20         register const char *cpdec;
  21         char buf[100];
  22
  23         /*
  24          * We understand numbers of the form:
  25          *
  26          * [spaces][-][digits][.][digits][spaces|\n|\0]
  27          *
  28          * This is one enormous hack.  Since I didn't feel like
  29          * rewriting the decoding routine for milliseconds, what
  30          * is essentially done here is to make a copy of the string
  31          * with the decimal moved over three places so the seconds
  32          * decoding routine can be used.
  33          */
  34         bp = buf;
  35         cp = str;
  36         while (isspace((int)*cp))
  37             cp++;
  38
  39         if (*cp == '-') {
  40                 *bp++ = '-';
  41                 cp++;
  42         }
  43
  44         if (*cp != '.' && !isdigit((int)*cp))
  45             return 0;
  46
  47
  48         /*
  49          * Search forward for the decimal point or the end of the string.
  50          */
  51         cpdec = cp;
  52         while (isdigit((int)*cpdec))
  53             cpdec++;
  54
  55         /*
  56          * Found something.  If we have more than three digits copy the
  57          * excess over, else insert a leading 0.
  58          */
  59         if ((cpdec - cp) > 3) {
  60                 do {
  61                         *bp++ = (char)*cp++;
  62                 } while ((cpdec - cp) > 3);
  63         } else {
  64                 *bp++ = '0';
  65         }
  66
  67         /*
  68          * Stick the decimal in.  If we've got less than three digits in
  69          * front of the millisecond decimal we insert the appropriate number
  70          * of zeros.
  71          */
  72         *bp++ = '.';
  73         if ((cpdec - cp) < 3) {
  74                 register int i = 3 - (cpdec - cp);
  75
  76                 do {
  77                         *bp++ = '0';
  78                 } while (--i > 0);
  79         }
  80
  81         /*
  82          * Copy the remainder up to the millisecond decimal.  If cpdec
  83          * is pointing at a decimal point, copy in the trailing number too.
  84          */
  85         while (cp < cpdec)
  86             *bp++ = (char)*cp++;
  87
  88         if (*cp == '.') {
  89                 cp++;
  90                 while (isdigit((int)*cp))
  91                     *bp++ = (char)*cp++;
  92         }
  93         *bp = '\0';
  94
  95         /*
  96          * Check to make sure the string is properly terminated.  If
  97          * so, give the buffer to the decoding routine.
  98          */
  99         if (*cp != '\0' && !isspace((int)*cp))
 100             return 0;
 101         return atolfp(buf, lfp);
 102 }