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/* Convert a floating-point number to string.
Copyright (C) 2016-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* Generic implementation for strfrom functions. The implementation is generic
for several floating-point types (e.g.: float, double), so that each
function, such as strfromf and strfroml, share the same code, thus avoiding
code duplication. */
#include <ctype.h>
#include "../libio/libioP.h"
#include "../libio/strfile.h"
#include <printf.h>
#include <string.h>
#include <locale/localeinfo.h>
#define UCHAR_T char
#define L_(Str) Str
#define ISDIGIT(Ch) isdigit (Ch)
#include "stdio-common/printf-parse.h"
int
STRFROM (char *dest, size_t size, const char *format, FLOAT f)
{
_IO_strnfile sfile;
#ifdef _IO_MTSAFE_IO
sfile.f._sbf._f._lock = NULL;
#endif
int done;
/* Single-precision values need to be stored in a double type, because
__printf_fp_l and __printf_fphex do not accept the float type. */
union {
double flt;
FLOAT value;
} fpnum;
const void *fpptr;
fpptr = &fpnum;
/* Variables to control the output format. */
int precision = -1; /* printf_fp and printf_fphex treat this internally. */
int specifier;
struct printf_info info;
/* Single-precision values need to be converted into double-precision,
because __printf_fp and __printf_fphex only accept double and long double
as the floating-point argument. */
if (__builtin_types_compatible_p (FLOAT, float))
fpnum.flt = f;
else
fpnum.value = f;
/* Check if the first character in the format string is indeed the '%'
character. Otherwise, abort. */
if (*format == '%')
format++;
else
abort ();
/* The optional precision specification always starts with a '.'. If such
character is present, read the precision. */
if (*format == '.')
{
format++;
/* Parse the precision. */
if (ISDIGIT (*format))
precision = read_int (&format);
/* If only the period is specified, the precision is taken as zero, as
described in ISO/IEC 9899:2011, section 7.21.6.1, 4th paragraph, 3rd
item. */
else
precision = 0;
}
/* Now there is only the conversion specifier to be read. */
switch (*format)
{
case 'a':
case 'A':
case 'e':
case 'E':
case 'f':
case 'F':
case 'g':
case 'G':
specifier = *format;
break;
default:
abort ();
}
/* The following code to prepare the virtual file has been adapted from the
function __vsnprintf_internal from libio. */
if (size == 0)
{
/* When size is zero, nothing is written and dest may be a null pointer.
This is specified for snprintf in ISO/IEC 9899:2011, Section 7.21.6.5,
in the second paragraph. Thus, if size is zero, prepare to use the
overflow buffer right from the start. */
dest = sfile.overflow_buf;
size = sizeof (sfile.overflow_buf);
}
/* Prepare the virtual string file. */
_IO_no_init (&sfile.f._sbf._f, _IO_USER_LOCK, -1, NULL, NULL);
_IO_JUMPS (&sfile.f._sbf) = &_IO_strn_jumps;
_IO_str_init_static_internal (&sfile.f, dest, size - 1, dest);
/* Prepare the format specification for printf_fp. */
memset (&info, '\0', sizeof (info));
/* The functions strfromd and strfromf pass a floating-point number with
double precision to printf_fp, whereas strfroml passes a floating-point
number with long double precision. The following line informs printf_fp
which type of floating-point number is being passed. */
info.is_long_double = __builtin_types_compatible_p (FLOAT, long double);
/* Similarly, the function strfromf128 passes a floating-point number in
_Float128 format to printf_fp. */
#if __HAVE_DISTINCT_FLOAT128
info.is_binary128 = __builtin_types_compatible_p (FLOAT, _Float128);
#endif
/* Set info according to the format string. */
info.prec = precision;
info.spec = specifier;
if (info.spec != 'a' && info.spec != 'A')
done = __printf_fp_l (&sfile.f._sbf._f, _NL_CURRENT_LOCALE, &info, &fpptr);
else
done = __printf_fphex (&sfile.f._sbf._f, &info, &fpptr);
/* Terminate the string. */
if (sfile.f._sbf._f._IO_buf_base != sfile.overflow_buf)
*sfile.f._sbf._f._IO_write_ptr = '\0';
return done;
}
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