1 85231fd8 2006-05-21 devnull /* Copyright (c) 2002-2006 Lucent Technologies; see LICENSE */
 2 91c13e54 2004-02-29 devnull #include <stdarg.h>
 3 91c13e54 2004-02-29 devnull #include <string.h>
 4 e5aa96ac 2004-12-26 devnull #include "plan9.h"
 5 91c13e54 2004-02-29 devnull #include "fmt.h"
 6 91c13e54 2004-02-29 devnull #include "fmtdef.h"
 7 91c13e54 2004-02-29 devnull 
 8 91c13e54 2004-02-29 devnull /*
 9 91c13e54 2004-02-29 devnull  * Reads a floating-point number by interpreting successive characters
10 91c13e54 2004-02-29 devnull  * returned by (*f)(vp).  The last call it makes to f terminates the
11 91c13e54 2004-02-29 devnull  * scan, so is not a character in the number.  It may therefore be
12 91c13e54 2004-02-29 devnull  * necessary to back up the input stream up one byte after calling charstod.
13 91c13e54 2004-02-29 devnull  */
14 91c13e54 2004-02-29 devnull 
15 91c13e54 2004-02-29 devnull double
16 91c13e54 2004-02-29 devnull fmtcharstod(int(*f)(void*), void *vp)
17 91c13e54 2004-02-29 devnull {
18 91c13e54 2004-02-29 devnull 	double num, dem;
19 91c13e54 2004-02-29 devnull 	int neg, eneg, dig, exp, c;
20 91c13e54 2004-02-29 devnull 
21 91c13e54 2004-02-29 devnull 	num = 0;
22 91c13e54 2004-02-29 devnull 	neg = 0;
23 91c13e54 2004-02-29 devnull 	dig = 0;
24 91c13e54 2004-02-29 devnull 	exp = 0;
25 91c13e54 2004-02-29 devnull 	eneg = 0;
26 91c13e54 2004-02-29 devnull 
27 91c13e54 2004-02-29 devnull 	c = (*f)(vp);
28 91c13e54 2004-02-29 devnull 	while(c == ' ' || c == '\t')
29 91c13e54 2004-02-29 devnull 		c = (*f)(vp);
30 91c13e54 2004-02-29 devnull 	if(c == '-' || c == '+'){
31 91c13e54 2004-02-29 devnull 		if(c == '-')
32 91c13e54 2004-02-29 devnull 			neg = 1;
33 91c13e54 2004-02-29 devnull 		c = (*f)(vp);
34 91c13e54 2004-02-29 devnull 	}
35 91c13e54 2004-02-29 devnull 	while(c >= '0' && c <= '9'){
36 91c13e54 2004-02-29 devnull 		num = num*10 + c-'0';
37 91c13e54 2004-02-29 devnull 		c = (*f)(vp);
38 91c13e54 2004-02-29 devnull 	}
39 91c13e54 2004-02-29 devnull 	if(c == '.')
40 91c13e54 2004-02-29 devnull 		c = (*f)(vp);
41 91c13e54 2004-02-29 devnull 	while(c >= '0' && c <= '9'){
42 91c13e54 2004-02-29 devnull 		num = num*10 + c-'0';
43 91c13e54 2004-02-29 devnull 		dig++;
44 91c13e54 2004-02-29 devnull 		c = (*f)(vp);
45 91c13e54 2004-02-29 devnull 	}
46 91c13e54 2004-02-29 devnull 	if(c == 'e' || c == 'E'){
47 91c13e54 2004-02-29 devnull 		c = (*f)(vp);
48 91c13e54 2004-02-29 devnull 		if(c == '-' || c == '+'){
49 91c13e54 2004-02-29 devnull 			if(c == '-'){
50 91c13e54 2004-02-29 devnull 				dig = -dig;
51 91c13e54 2004-02-29 devnull 				eneg = 1;
52 91c13e54 2004-02-29 devnull 			}
53 91c13e54 2004-02-29 devnull 			c = (*f)(vp);
54 91c13e54 2004-02-29 devnull 		}
55 91c13e54 2004-02-29 devnull 		while(c >= '0' && c <= '9'){
56 91c13e54 2004-02-29 devnull 			exp = exp*10 + c-'0';
57 91c13e54 2004-02-29 devnull 			c = (*f)(vp);
58 91c13e54 2004-02-29 devnull 		}
59 91c13e54 2004-02-29 devnull 	}
60 91c13e54 2004-02-29 devnull 	exp -= dig;
61 91c13e54 2004-02-29 devnull 	if(exp < 0){
62 91c13e54 2004-02-29 devnull 		exp = -exp;
63 91c13e54 2004-02-29 devnull 		eneg = !eneg;
64 91c13e54 2004-02-29 devnull 	}
65 91c13e54 2004-02-29 devnull 	dem = __fmtpow10(exp);
66 91c13e54 2004-02-29 devnull 	if(eneg)
67 91c13e54 2004-02-29 devnull 		num /= dem;
68 91c13e54 2004-02-29 devnull 	else
69 91c13e54 2004-02-29 devnull 		num *= dem;
70 91c13e54 2004-02-29 devnull 	if(neg)
71 91c13e54 2004-02-29 devnull 		return -num;
72 91c13e54 2004-02-29 devnull 	return num;
73 91c13e54 2004-02-29 devnull }