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133 lines
4.2 KiB
C
133 lines
4.2 KiB
C
/* Convert a floating-point number to string.
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Copyright (C) 2016-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Generic implementation for strfrom functions. The implementation is generic
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for several floating-point types (e.g.: float, double), so that each
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function, such as strfromf and strfroml, share the same code, thus avoiding
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code duplication. */
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#include <ctype.h>
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#include "../libio/libioP.h"
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#include "../libio/strfile.h"
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#include <printf.h>
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#include <string.h>
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#include <locale/localeinfo.h>
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#include <fix-float-double-convert-nan.h>
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#include <printf_buffer.h>
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#define UCHAR_T char
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#define L_(Str) Str
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#define ISDIGIT(Ch) isdigit (Ch)
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#include "stdio-common/printf-parse.h"
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int
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STRFROM (char *dest, size_t size, const char *format, FLOAT f)
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{
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struct __printf_buffer_snprintf buf;
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/* Single-precision values need to be stored in a double type, because
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__printf_fp_l and __printf_fphex do not accept the float type. */
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union {
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double flt;
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FLOAT value;
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} fpnum;
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const void *fpptr;
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fpptr = &fpnum;
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/* Variables to control the output format. */
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int precision = -1; /* printf_fp and printf_fphex treat this internally. */
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int specifier;
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struct printf_info info;
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/* Single-precision values need to be converted into double-precision,
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because __printf_fp and __printf_fphex only accept double and long double
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as the floating-point argument. */
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if (__builtin_types_compatible_p (FLOAT, float))
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fpnum.flt = keep_sign_conversion (f);
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else
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fpnum.value = f;
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/* Check if the first character in the format string is indeed the '%'
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character. Otherwise, abort. */
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if (*format == '%')
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format++;
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else
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abort ();
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/* The optional precision specification always starts with a '.'. If such
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character is present, read the precision. */
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if (*format == '.')
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{
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format++;
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/* Parse the precision. */
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if (ISDIGIT (*format))
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precision = read_int (&format);
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/* If only the period is specified, the precision is taken as zero, as
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described in ISO/IEC 9899:2011, section 7.21.6.1, 4th paragraph, 3rd
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item. */
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else
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precision = 0;
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}
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/* Now there is only the conversion specifier to be read. */
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switch (*format)
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{
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case 'a':
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case 'A':
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case 'e':
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case 'E':
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case 'f':
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case 'F':
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case 'g':
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case 'G':
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specifier = *format;
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break;
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default:
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abort ();
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}
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/* Prepare the string buffer. */
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__printf_buffer_snprintf_init (&buf, dest, size);
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/* Prepare the format specification for printf_fp. */
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memset (&info, '\0', sizeof (info));
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/* The functions strfromd and strfromf pass a floating-point number with
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double precision to printf_fp, whereas strfroml passes a floating-point
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number with long double precision. The following line informs printf_fp
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which type of floating-point number is being passed. */
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info.is_long_double = __builtin_types_compatible_p (FLOAT, long double);
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/* Similarly, the function strfromf128 passes a floating-point number in
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_Float128 format to printf_fp. */
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#if __HAVE_DISTINCT_FLOAT128
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info.is_binary128 = __builtin_types_compatible_p (FLOAT, _Float128);
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#endif
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/* Set info according to the format string. */
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info.prec = precision;
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info.spec = specifier;
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if (info.spec != 'a' && info.spec != 'A')
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__printf_fp_l_buffer (&buf.base, _NL_CURRENT_LOCALE, &info, &fpptr);
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else
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__printf_fphex_l_buffer (&buf.base, _NL_CURRENT_LOCALE, &info, &fpptr);
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return __printf_buffer_snprintf_done (&buf);
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}
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