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comparison sprintf/float.c @ 0:75a11d740a02

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initial import of gsm-fw from freecalypso-sw rev 1033:5ab737ac3ad7
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 09 Jun 2016 00:02:41 +0000
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children a2d5d622e19e
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-1:000000000000 0:75a11d740a02
1 /*
2 * Embedded [v]sprintf() implementation by Michael Spacefalcon,
3 * loosely based on the 4.3BSD-Tahoe version.
4 *
5 * This module contains the floating point conversion functions.
6 */
7
8 #include <sys/types.h>
9 #include <ctype.h>
10 #include "defs.h"
11
12 extern double modf();
13
14 extern u_char * _sprintf_field(u_char *op, int width, int flags, int sign,
15 u_char *body, int size, int dprec, int fpprec);
16
17 #define MAX_INT_DIGITS 10 /* 2^32-1 in decimal */
18 #define MAXFRACT 16 /* max sensible for 64-bit double */
19 #define DEFPREC 6
20
21 static char *
22 emit_integer_portion(unsigned number, char *endp)
23 {
24 char *t = endp;
25
26 do {
27 *--t = tochar(number % 10);
28 number /= 10;
29 } while (number);
30 return (t);
31 }
32
33 static int
34 f_round(double fract, char *start, char *end, int sign)
35 {
36 double tmp;
37
38 (void)modf(fract * 10, &tmp);
39 if (tmp > 4)
40 for (;; --end) {
41 if (*end == '.')
42 --end;
43 if (++*end <= '9')
44 break;
45 *end = '0';
46 }
47 /* ``"%.3f", (double)-0.0004'' gives you a negative 0. */
48 else if (sign == '-')
49 for (;; --end) {
50 if (*end == '.')
51 --end;
52 if (*end != '0')
53 break;
54 if (end == start)
55 return(1); /* clear the -ve */
56 }
57 return(0);
58 }
59
60 u_char *
61 _sprintf_percent_f(u_char *op, int width, int flags, int sign,
62 double number, int prec)
63 {
64 char buf[MAX_INT_DIGITS + 1 + MAXFRACT];
65 int extra_prec = 0;
66 int origsign = sign;
67 double fract, tmp;
68 char *start, *t;
69
70 /* first order of business: weed out infinities and NaNs */
71 if (isinf(number)) {
72 if (number < 0)
73 sign = '-';
74 return _sprintf_field(op, width, flags, sign, "Inf", 3, 0, 0);
75 }
76 if (isnan(number))
77 return _sprintf_field(op, width, flags, sign, "NaN", 3, 0, 0);
78 /* OK, we know it's a valid real like in the good old VAX days */
79 if (number < 0) {
80 sign = '-';
81 number = -number;
82 }
83 fract = modf(number, &tmp);
84 if (tmp > (double) 0xFFFFFFFF)
85 return _sprintf_field(op, width, flags, sign, "Toobig", 6,
86 0, 0);
87 start = emit_integer_portion((unsigned) tmp, buf + MAX_INT_DIGITS);
88 if (prec > MAXFRACT) {
89 extra_prec = prec - MAXFRACT;
90 prec = MAXFRACT;
91 } else if (prec == -1)
92 prec = DEFPREC;
93 t = buf + MAX_INT_DIGITS;
94 /*
95 * if precision required or alternate flag set, add in a
96 * decimal point.
97 */
98 if (prec || flags&ALT)
99 *t++ = '.';
100 /* if requires more precision and some fraction left */
101 if (fract) {
102 if (prec)
103 do {
104 fract = modf(fract * 10, &tmp);
105 *t++ = tochar((int)tmp);
106 } while (--prec && fract);
107 if (fract && f_round(fract, start, t - 1, sign))
108 sign = origsign;
109 }
110 return _sprintf_field(op, width, flags, sign, start, t - start,
111 0, prec + extra_prec);
112 }