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6962682f | 1 | /* Convert a floating-point number to string. |
688903eb | 2 | Copyright (C) 2016-2018 Free Software Foundation, Inc. |
6962682f GG |
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 | <http://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 | ||
31 | #define UCHAR_T char | |
32 | #define L_(Str) Str | |
33 | #define ISDIGIT(Ch) isdigit (Ch) | |
34 | #include "stdio-common/printf-parse.h" | |
35 | ||
36 | int | |
37 | STRFROM (char *dest, size_t size, const char *format, FLOAT f) | |
38 | { | |
39 | _IO_strnfile sfile; | |
40 | #ifdef _IO_MTSAFE_IO | |
41 | sfile.f._sbf._f._lock = NULL; | |
42 | #endif | |
43 | ||
44 | int done; | |
45 | ||
46 | /* Single-precision values need to be stored in a double type, because | |
47 | __printf_fp_l and __printf_fphex do not accept the float type. */ | |
48 | union { | |
49 | double flt; | |
50 | FLOAT value; | |
51 | } fpnum; | |
52 | const void *fpptr; | |
53 | fpptr = &fpnum; | |
54 | ||
55 | /* Variables to control the output format. */ | |
56 | int precision = -1; /* printf_fp and printf_fphex treat this internally. */ | |
57 | int specifier; | |
58 | struct printf_info info; | |
59 | ||
60 | /* Single-precision values need to be converted into double-precision, | |
61 | because __printf_fp and __printf_fphex only accept double and long double | |
62 | as the floating-point argument. */ | |
63 | if (__builtin_types_compatible_p (FLOAT, float)) | |
64 | fpnum.flt = f; | |
65 | else | |
66 | fpnum.value = f; | |
67 | ||
68 | /* Check if the first character in the format string is indeed the '%' | |
69 | character. Otherwise, abort. */ | |
70 | if (*format == '%') | |
71 | format++; | |
72 | else | |
73 | abort (); | |
74 | ||
75 | /* The optional precision specification always starts with a '.'. If such | |
76 | character is present, read the precision. */ | |
77 | if (*format == '.') | |
78 | { | |
79 | format++; | |
80 | ||
81 | /* Parse the precision. */ | |
82 | if (ISDIGIT (*format)) | |
83 | precision = read_int (&format); | |
84 | /* If only the period is specified, the precision is taken as zero, as | |
85 | described in ISO/IEC 9899:2011, section 7.21.6.1, 4th paragraph, 3rd | |
86 | item. */ | |
87 | else | |
88 | precision = 0; | |
89 | } | |
90 | ||
91 | /* Now there is only the conversion specifier to be read. */ | |
92 | switch (*format) | |
93 | { | |
94 | case 'a': | |
95 | case 'A': | |
96 | case 'e': | |
97 | case 'E': | |
98 | case 'f': | |
99 | case 'F': | |
100 | case 'g': | |
101 | case 'G': | |
102 | specifier = *format; | |
103 | break; | |
104 | default: | |
105 | abort (); | |
106 | } | |
107 | ||
108 | /* The following code to prepare the virtual file has been adapted from the | |
109 | function _IO_vsnprintf from libio. */ | |
110 | ||
111 | if (size == 0) | |
112 | { | |
113 | /* When size is zero, nothing is written and dest may be a null pointer. | |
114 | This is specified for snprintf in ISO/IEC 9899:2011, Section 7.21.6.5, | |
115 | in the second paragraph. Thus, if size is zero, prepare to use the | |
116 | overflow buffer right from the start. */ | |
117 | dest = sfile.overflow_buf; | |
118 | size = sizeof (sfile.overflow_buf); | |
119 | } | |
120 | ||
121 | /* Prepare the virtual string file. */ | |
122 | _IO_no_init (&sfile.f._sbf._f, _IO_USER_LOCK, -1, NULL, NULL); | |
123 | _IO_JUMPS (&sfile.f._sbf) = &_IO_strn_jumps; | |
124 | _IO_str_init_static_internal (&sfile.f, dest, size - 1, dest); | |
125 | ||
126 | /* Prepare the format specification for printf_fp. */ | |
127 | memset (&info, '\0', sizeof (info)); | |
128 | ||
129 | /* The functions strfromd and strfromf pass a floating-point number with | |
130 | double precision to printf_fp, whereas strfroml passes a floating-point | |
131 | number with long double precision. The following line informs printf_fp | |
132 | which type of floating-point number is being passed. */ | |
133 | info.is_long_double = __builtin_types_compatible_p (FLOAT, long double); | |
134 | ||
cf2046ec GG |
135 | /* Similarly, the function strfromf128 passes a floating-point number in |
136 | _Float128 format to printf_fp. */ | |
137 | #if __HAVE_DISTINCT_FLOAT128 | |
138 | info.is_binary128 = __builtin_types_compatible_p (FLOAT, _Float128); | |
139 | #endif | |
140 | ||
6962682f GG |
141 | /* Set info according to the format string. */ |
142 | info.prec = precision; | |
143 | info.spec = specifier; | |
144 | ||
145 | if (info.spec != 'a' && info.spec != 'A') | |
146 | done = __printf_fp_l (&sfile.f._sbf._f, _NL_CURRENT_LOCALE, &info, &fpptr); | |
147 | else | |
148 | done = __printf_fphex (&sfile.f._sbf._f, &info, &fpptr); | |
149 | ||
150 | /* Terminate the string. */ | |
151 | if (sfile.f._sbf._f._IO_buf_base != sfile.overflow_buf) | |
152 | *sfile.f._sbf._f._IO_write_ptr = '\0'; | |
153 | ||
154 | return done; | |
155 | } |