external/bsd/ntp/dist/libntp/atolfp.c

   1 /*      $NetBSD: atolfp.c,v 1.1.1.1 2009/12/13 16:55:01 kardel Exp $    */
   2
   3 /*
   4  * atolfp - convert an ascii 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_assert.h"
  12
  13 /*
  14  * Powers of 10
  15  */
  16 static u_long ten_to_the_n[10] = {
  17         0,
  18         10,
  19         100,
  20         1000,
  21         10000,
  22         100000,
  23         1000000,
  24         10000000,
  25         100000000,
  26         1000000000,
  27 };
  28
  29
  30 int
  31 atolfp(
  32         const char *str,
  33         l_fp *lfp
  34         )
  35 {
  36         register const char *cp;
  37         register u_long dec_i;
  38         register u_long dec_f;
  39         char *ind;
  40         int ndec;
  41         int isneg;
  42         static const char *digits = "0123456789";
  43
  44         NTP_REQUIRE(str != NULL);
  45
  46         isneg = 0;
  47         dec_i = dec_f = 0;
  48         ndec = 0;
  49         cp = str;
  50
  51         /*
  52          * We understand numbers of the form:
  53          *
  54          * [spaces][-|+][digits][.][digits][spaces|\n|\0]
  55          */
  56         while (isspace((unsigned char)*cp))
  57             cp++;
  58
  59         if (*cp == '-') {
  60                 cp++;
  61                 isneg = 1;
  62         }
  63
  64         if (*cp == '+')
  65             cp++;
  66
  67         if (*cp != '.' && !isdigit((unsigned char)*cp))
  68             return 0;
  69
  70         while (*cp != '\0' && (ind = strchr(digits, *cp)) != NULL) {
  71                 dec_i = (dec_i << 3) + (dec_i << 1);    /* multiply by 10 */
  72                 dec_i += (ind - digits);
  73                 cp++;
  74         }
  75
  76         if (*cp != '\0' && !isspace((unsigned char)*cp)) {
  77                 if (*cp++ != '.')
  78                     return 0;
  79
  80                 while (ndec < 9 && *cp != '\0'
  81                        && (ind = strchr(digits, *cp)) != NULL) {
  82                         ndec++;
  83                         dec_f = (dec_f << 3) + (dec_f << 1);    /* *10 */
  84                         dec_f += (ind - digits);
  85                         cp++;
  86                 }
  87
  88                 while (isdigit((unsigned char)*cp))
  89                     cp++;
  90
  91                 if (*cp != '\0' && !isspace((unsigned char)*cp))
  92                     return 0;
  93         }
  94
  95         if (ndec > 0) {
  96                 register u_long tmp;
  97                 register u_long bit;
  98                 register u_long ten_fact;
  99
 100                 ten_fact = ten_to_the_n[ndec];
 101
 102                 tmp = 0;
 103                 bit = 0x80000000;
 104                 while (bit != 0) {
 105                         dec_f <<= 1;
 106                         if (dec_f >= ten_fact) {
 107                                 tmp |= bit;
 108                                 dec_f -= ten_fact;
 109                         }
 110                         bit >>= 1;
 111                 }
 112                 if ((dec_f << 1) > ten_fact)
 113                     tmp++;
 114                 dec_f = tmp;
 115         }
 116
 117         if (isneg)
 118             M_NEG(dec_i, dec_f);
 119
 120         lfp->l_ui = dec_i;
 121         lfp->l_uf = dec_f;
 122         return 1;
 123 }