glibc/sysdeps/ieee754/ldbl2mpn.c
Roland McGrath ce563359af Wed Mar 20 11:28:49 1996 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* stdio-common/printf.h, stdio-common/printf_fp.c,
	stdio-common/vfprintf.c: Place const in parameter list at
	correct place.

Wed Mar 20 23:58.12 1996  Ulrich Drepper <drepper@gnu.ai.mit.edu>

	* sysdeps/i386/ldbl2mpn.c: Copy of former version of
	sysdeps/ieee754/ldbl2mpn.c.
	* sysdeps/ieee754/ldbl2mpn.c: Remove i386 specific unification.
	Reported by Andreas Schwab.

Wed Mar 20 19:58:43 1996  Roland McGrath  <roland@charlie-brown.gnu.ai.mit.edu>

	* version.c: Include version.h to define RELEASE and VERSION macros.
	(__libc_release, __libc_version): Use them.
	* locale/SYS_libc.c (_libc_intl_domainname): Include ../version.h and
	use VERSION to define domainname as `SYS_GNU_libc-VERSION'.
	* Make-dist (rel+vers): Snarf the macro values from version.h.

	* MakeTAGS (extract): Pass $(XGETTEXTFLAGS-$(@F)).
	(XGETTEXTFLAGS-siglist.pot, XGETTEXTFLAGS-errlist.pot): New variables;
	pass -a for these files.

	* Makerules (po/%.pot): Depend on FORCE target so recursive make is
	always run.
1996-03-21 15:20:37 +00:00

95 lines
2.9 KiB
C

/* Copyright (C) 1995, 1996 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"
#include "ieee754.h"
#include <float.h>
#include <stdlib.h>
/* Convert a `long double' in IEEE854 standard double-precision format to a
multi-precision integer representing the significand scaled up by its
number of bits (64 for long double) and an integral power of two
(MPN frexpl). */
mp_size_t
__mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size,
int *expt, int *is_neg,
long double value)
{
union ieee854_long_double u;
u.d = value;
*is_neg = u.ieee.negative;
*expt = (int) u.ieee.exponent - IEEE854_LONG_DOUBLE_BIAS;
#if BITS_PER_MP_LIMB == 32
res_ptr[0] = u.ieee.mantissa1; /* Low-order 32 bits of fraction. */
res_ptr[1] = u.ieee.mantissa0; /* High-order 32 bits. */
#define N 2
#elif BITS_PER_MP_LIMB == 64
/* Hopefully the compiler will combine the two bitfield extracts
and this composition into just the original quadword extract. */
res_ptr[0] = ((unsigned long int) u.ieee.mantissa0 << 32) | u.ieee.mantissa1;
#define N 1
#else
#error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
#endif
if (u.ieee.exponent == 0)
{
/* A biased exponent of zero is a special case.
Either it is a zero or it is a denormal number. */
if (res_ptr[0] == 0 && res_ptr[N - 1] == 0) /* Assumes N<=2. */
/* It's zero. */
*expt = 0;
else
{
/* It is a denormal number, meaning it has no implicit leading
one bit, and its exponent is in fact the format minimum. */
int cnt;
if (res_ptr[N - 1] != 0)
{
count_leading_zeros (cnt, res_ptr[N - 1]);
if (cnt != 0)
{
#if N == 2
res_ptr[N - 1] = res_ptr[N - 1] << cnt
| (res_ptr[0] >> (BITS_PER_MP_LIMB - cnt));
res_ptr[0] <<= cnt;
#else
res_ptr[N - 1] <<= cnt;
#endif
}
*expt = LDBL_MIN_EXP - 1 - cnt;
}
else
{
count_leading_zeros (cnt, res_ptr[0]);
res_ptr[N - 1] = res_ptr[0] << cnt;
res_ptr[0] = 0;
*expt = LDBL_MIN_EXP - 1 - BITS_PER_MP_LIMB - cnt;
}
}
}
return N;
}