1/* Convert a floating-point number to string.
2 Copyright (C) 2016-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19/* Generic implementation for strfrom functions. The implementation is generic
20 for several floating-point types (e.g.: float, double), so that each
21 function, such as strfromf and strfroml, share the same code, thus avoiding
22 code duplication. */
23
24#include <ctype.h>
25#include "../libio/libioP.h"
26#include "../libio/strfile.h"
27#include <printf.h>
28#include <string.h>
29#include <locale/localeinfo.h>
30#include <fix-float-double-convert-nan.h>
31#include <printf_buffer.h>
32
33#define UCHAR_T char
34#define L_(Str) Str
35#define ISDIGIT(Ch) isdigit (Ch)
36#include "stdio-common/printf-parse.h"
37
38int
39STRFROM (char *dest, size_t size, const char *format, FLOAT f)
40{
41 struct __printf_buffer_snprintf buf;
42
43 /* Single-precision values need to be stored in a double type, because
44 __printf_fp_l and __printf_fphex do not accept the float type. */
45 union {
46 double flt;
47 FLOAT value;
48 } fpnum;
49 const void *fpptr;
50 fpptr = &fpnum;
51
52 /* Variables to control the output format. */
53 int precision = -1; /* printf_fp and printf_fphex treat this internally. */
54 int specifier;
55 struct printf_info info;
56
57 /* Single-precision values need to be converted into double-precision,
58 because __printf_fp and __printf_fphex only accept double and long double
59 as the floating-point argument. */
60 if (__builtin_types_compatible_p (FLOAT, float))
61 fpnum.flt = keep_sign_conversion (f);
62 else
63 fpnum.value = f;
64
65 /* Check if the first character in the format string is indeed the '%'
66 character. Otherwise, abort. */
67 if (*format == '%')
68 format++;
69 else
70 abort ();
71
72 /* The optional precision specification always starts with a '.'. If such
73 character is present, read the precision. */
74 if (*format == '.')
75 {
76 format++;
77
78 /* Parse the precision. */
79 if (ISDIGIT (*format))
80 precision = read_int (&format);
81 /* If only the period is specified, the precision is taken as zero, as
82 described in ISO/IEC 9899:2011, section 7.21.6.1, 4th paragraph, 3rd
83 item. */
84 else
85 precision = 0;
86 }
87
88 /* Now there is only the conversion specifier to be read. */
89 switch (*format)
90 {
91 case 'a':
92 case 'A':
93 case 'e':
94 case 'E':
95 case 'f':
96 case 'F':
97 case 'g':
98 case 'G':
99 specifier = *format;
100 break;
101 default:
102 abort ();
103 }
104
105 /* Prepare the string buffer. */
106 __printf_buffer_snprintf_init (&buf, dest, size);
107
108 /* Prepare the format specification for printf_fp. */
109 memset (&info, '\0', sizeof (info));
110
111 /* The functions strfromd and strfromf pass a floating-point number with
112 double precision to printf_fp, whereas strfroml passes a floating-point
113 number with long double precision. The following line informs printf_fp
114 which type of floating-point number is being passed. */
115 info.is_long_double = __builtin_types_compatible_p (FLOAT, long double);
116
117 /* Similarly, the function strfromf128 passes a floating-point number in
118 _Float128 format to printf_fp. */
119#if __HAVE_DISTINCT_FLOAT128
120 info.is_binary128 = __builtin_types_compatible_p (FLOAT, _Float128);
121#endif
122
123 /* Set info according to the format string. */
124 info.prec = precision;
125 info.spec = specifier;
126
127 if (info.spec != 'a' && info.spec != 'A')
128 __printf_fp_l_buffer (&buf.base, _NL_CURRENT_LOCALE, &info, &fpptr);
129 else
130 __printf_fphex_l_buffer (&buf.base, _NL_CURRENT_LOCALE, &info, &fpptr);
131 return __printf_buffer_snprintf_done (&buf);
132}
133