freebsd-dev/contrib/ntp/libntp/atolfp.c
Xin LI 3311ff84ea MFV r293415:
ntp 4.2.8p5

Reviewed by:	cy, roberto
Relnotes:	yes
Differential Revision:	https://reviews.freebsd.org/D4828
2016-01-08 15:53:48 +00:00

123 lines
1.9 KiB
C

/*
* atolfp - convert an ascii string to an l_fp number
*/
#include <config.h>
#include <stdio.h>
#include <ctype.h>
#include "ntp_fp.h"
#include "ntp_string.h"
#include "ntp_assert.h"
/*
* Powers of 10
*/
static u_long ten_to_the_n[10] = {
0,
10,
100,
1000,
10000,
100000,
1000000,
10000000,
100000000,
1000000000,
};
int
atolfp(
const char *str,
l_fp *lfp
)
{
register const char *cp;
register u_long dec_i;
register u_long dec_f;
char *ind;
int ndec;
int isneg;
static const char *digits = "0123456789";
REQUIRE(str != NULL);
isneg = 0;
dec_i = dec_f = 0;
ndec = 0;
cp = str;
/*
* We understand numbers of the form:
*
* [spaces][-|+][digits][.][digits][spaces|\n|\0]
*/
while (isspace((unsigned char)*cp))
cp++;
if (*cp == '-') {
cp++;
isneg = 1;
}
if (*cp == '+')
cp++;
if (*cp != '.' && !isdigit((unsigned char)*cp))
return 0;
while (*cp != '\0' && (ind = strchr(digits, *cp)) != NULL) {
dec_i = (dec_i << 3) + (dec_i << 1); /* multiply by 10 */
dec_i += (u_long)(ind - digits);
cp++;
}
if (*cp != '\0' && !isspace((unsigned char)*cp)) {
if (*cp++ != '.')
return 0;
while (ndec < 9 && *cp != '\0'
&& (ind = strchr(digits, *cp)) != NULL) {
ndec++;
dec_f = (dec_f << 3) + (dec_f << 1); /* *10 */
dec_f += (u_long)(ind - digits);
cp++;
}
while (isdigit((unsigned char)*cp))
cp++;
if (*cp != '\0' && !isspace((unsigned char)*cp))
return 0;
}
if (ndec > 0) {
register u_long tmp;
register u_long bit;
register u_long ten_fact;
ten_fact = ten_to_the_n[ndec];
tmp = 0;
bit = 0x80000000;
while (bit != 0) {
dec_f <<= 1;
if (dec_f >= ten_fact) {
tmp |= bit;
dec_f -= ten_fact;
}
bit >>= 1;
}
if ((dec_f << 1) > ten_fact)
tmp++;
dec_f = tmp;
}
if (isneg)
M_NEG(dec_i, dec_f);
lfp->l_ui = dec_i;
lfp->l_uf = dec_f;
return 1;
}