xref: /freebsd/contrib/ntp/libntp/hextolfp.c (revision 39ee7a7a6bdd1557b1c3532abf60d139798ac88b)
1 /*
2  * hextolfp - convert an ascii hex string to an l_fp number
3  */
4 #include <config.h>
5 #include <stdio.h>
6 #include <ctype.h>
7 
8 #include "ntp_fp.h"
9 #include "ntp_string.h"
10 #include "ntp_stdlib.h"
11 
12 int
13 hextolfp(
14 	const char *str,
15 	l_fp *lfp
16 	)
17 {
18 	register const char *cp;
19 	register const char *cpstart;
20 	register u_long dec_i;
21 	register u_long dec_f;
22 	char *ind = NULL;
23 	static const char *digits = "0123456789abcdefABCDEF";
24 
25 	dec_i = dec_f = 0;
26 	cp = str;
27 
28 	/*
29 	 * We understand numbers of the form:
30 	 *
31 	 * [spaces]8_hex_digits[.]8_hex_digits[spaces|\n|\0]
32 	 */
33 	while (isspace((unsigned char)*cp))
34 	    cp++;
35 
36 	cpstart = cp;
37 	while (*cp != '\0' && (cp - cpstart) < 8 &&
38 	       (ind = strchr(digits, *cp)) != NULL) {
39 		dec_i = dec_i << 4;	/* multiply by 16 */
40 		dec_i += ((ind - digits) > 15) ? (ind - digits) - 6
41 			: (ind - digits);
42 		cp++;
43 	}
44 
45 	if ((cp - cpstart) < 8 || ind == NULL)
46 	    return 0;
47 	if (*cp == '.')
48 	    cp++;
49 
50 	cpstart = cp;
51 	while (*cp != '\0' && (cp - cpstart) < 8 &&
52 	       (ind = strchr(digits, *cp)) != NULL) {
53 		dec_f = dec_f << 4;	/* multiply by 16 */
54 		dec_f += ((ind - digits) > 15) ? (ind - digits) - 6
55 			: (ind - digits);
56 		cp++;
57 	}
58 
59 	if ((cp - cpstart) < 8 || ind == NULL)
60 	    return 0;
61 
62 	if (*cp != '\0' && !isspace((unsigned char)*cp))
63 	    return 0;
64 
65 	lfp->l_ui = dec_i;
66 	lfp->l_uf = dec_f;
67 	return 1;
68 }
69