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/* Gldtoa.cc provides access to long double string conversion.
Copyright (C) 2016-2025 Free Software Foundation, Inc.
Contributed by Gaius Mulley <gaius@glam.ac.uk>.
This file is part of GNU Modula-2.
GNU Modula-2 is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GNU Modula-2 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Modula-2; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "gm2-libs-host.h"
#ifdef __cplusplus
extern "C" {
#endif
#define MAX_FP_DIGITS 500
typedef enum Mode { maxsignicant, decimaldigits } Mode;
extern int dtoa_calcmaxsig (char *p, int ndigits);
extern int dtoa_calcdecimal (char *p, int str_size, int ndigits);
extern bool dtoa_calcsign (char *p, int str_size);
/* maxsignicant: return a string containing max(1,ndigits)
significant digits. The return string contains the string
produced by snprintf. decimaldigits: return a string produced by
fcvt. The string will contain ndigits past the decimal point
(ndigits may be negative). */
long double
ldtoa_strtold (void *s, bool *error)
{
char *endp;
long double d;
errno = 0;
#if defined(HAVE_STRTOLD)
d = strtold (reinterpret_cast <char *> (s), &endp);
#else
/* fall back to using strtod. */
d = (long double)strtod (reinterpret_cast <char *> (s), &endp);
#endif
if (endp != NULL && (*endp == '\0'))
*error = (errno != 0);
else
*error = true;
return d;
}
void *
ldtoa_ldtoa (long double d, int mode, int ndigits, int *decpt, bool *sign)
{
char format[50];
char *p;
int r;
switch (mode)
{
case maxsignicant:
ndigits += 20; /* enough for exponent. */
p = (char *)malloc (ndigits);
snprintf (format, 50, "%s%d%s", "%.", ndigits - 20, "LE");
snprintf (p, ndigits, format, d);
*sign = dtoa_calcsign (p, ndigits);
*decpt = dtoa_calcmaxsig (p, ndigits);
return p;
case decimaldigits:
p = (char *)malloc (MAX_FP_DIGITS + 20);
snprintf (format, 50, "%s%d%s", "%.", MAX_FP_DIGITS, "LE");
snprintf (p, MAX_FP_DIGITS + 20, format, d);
*sign = dtoa_calcsign (p, MAX_FP_DIGITS + 20);
*decpt = dtoa_calcdecimal (p, MAX_FP_DIGITS + 20, ndigits);
return p;
default:
abort ();
}
}
/* GNU Modula-2 hooks */
void
_M2_ldtoa_init (int argc, char *argv[], char *envp[])
{
}
void
_M2_ldtoa_fini (int argc, char *argv[], char *envp[])
{
}
# ifdef __cplusplus
}
# endif
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