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Taken from http://sources.redhat.com/ml/crossgcc/2004-02/msg00104.html
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Author: addsub@eyou.com
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Target: ARM
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Fixes http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/920501-8.c
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and makes printf("%f", 1.0) work.
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Lennert Buytenhek wrote in http://sources.redhat.com/ml/crossgcc/2004-09/msg00115.html :
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It ... fixes the 'printf("%f\n", 0.5); prints 0.000000' and general 'floating point
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is broken' on my big-endian hardfloat FPA ARM platform. ...
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It's definitely needed for hardfloat. So I'd think it's needed for
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big-endian systems in any case, and for VFP on little-endian systems
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too. Someone would have to verify that though.
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Lennert Buytenhek wrote in http://sources.redhat.com/ml/crossgcc/2004-09/msg00123.html
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I just had a look at glibc-20040830, and [this patch] is still needed and useful
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for this version. glibc-20040830 out-of-the-box still contains the
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following wrong assumptions:
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- sysdeps/arm/bits/endian.h: float word order is big endian (which it is
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not on vfp systems)
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- sysdeps/arm/gmp-mparam.h: IEEE doubles are mixed endian (which they
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are not on big endian systems, neither on vfp systems)
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- sysdeps/arm/ieee754.h: IEEE doubles are in little endian byte order
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(which they are not on big endian systems)
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[This patch] seems the right solution for all of these issues.
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Dimitry Andric wrote in http://sources.redhat.com/ml/crossgcc/2004-09/msg00132.html :
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It's even needed for glibc CVS, AFAICS.
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The patch hunk which modifies glibc.new/sysdeps/arm/bits/endian.h
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(currently at version 1.4) is only needed for proper VFP operation.
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But the hunk which modifies sysdeps/arm/gmp-mparam.h, and the hunk
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that deletes sysdeps/arm/ieee754.h (yes, this IS correct), are needed
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for proper operation of *any* FP model on big endian ARM.
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See also discussion in followups to
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http://sources.redhat.com/ml/crossgcc/2004-05/msg00245.html)
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Message-ID: <276985760.37584@eyou.com>
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Received: from unknown (HELO eyou.com) (172.16.2.2)
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by 0.0.0.0 with SMTP; Tue, 17 Feb 2004 10:42:40 +0800
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Received: (qmail 8238 invoked by uid 65534); 17 Feb 2004 10:42:38 +0800
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Date: 17 Feb 2004 10:42:38 +0800
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Message-ID: <20040217104238.8237.qmail@eyou.com>
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From: "add" <addsub@eyou.com>
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To: dank@kegel.com
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Reply-To: "add" <addsub@eyou.com>
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Subject: Re: problem while building arm vfp softfloat gcc `
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Hi, Dan, This is a patch I applied to my glibc-2.3.2, then my softfloat
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toolchain can printf("%f\n",1.0). So you may have a try of this
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diff -uNrp glibc.old/sysdeps/arm/bits/endian.h glibc.new/sysdeps/arm/bits/endian.h
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--- glibc.old/sysdeps/arm/bits/endian.h 1999-04-12 11:59:13.000000000 -0400
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+++ glibc.new/sysdeps/arm/bits/endian.h 2004-02-12 09:15:13.000000000 -0500
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@@ -9,4 +9,9 @@
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#else
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#define __BYTE_ORDER __LITTLE_ENDIAN
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#endif
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+
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+#ifdef __VFP_FP__
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+#define __FLOAT_WORD_ORDER __BYTE_ORDER
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+#else
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#define __FLOAT_WORD_ORDER __BIG_ENDIAN
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+#endif
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diff -uNrp glibc.old/sysdeps/arm/gmp-mparam.h glibc.new/sysdeps/arm/gmp-mparam.h
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--- glibc.old/sysdeps/arm/gmp-mparam.h 2001-07-07 15:21:19.000000000 -0400
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+++ glibc.new/sysdeps/arm/gmp-mparam.h 2004-02-12 09:15:13.000000000 -0500
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@@ -26,5 +26,13 @@ MA 02111-1307, USA. */
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#define BITS_PER_SHORTINT 16
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#define BITS_PER_CHAR 8
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-#define IEEE_DOUBLE_BIG_ENDIAN 0
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-#define IEEE_DOUBLE_MIXED_ENDIAN 1
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+#if defined(__ARMEB__)
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+# define IEEE_DOUBLE_MIXED_ENDIAN 0
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+# define IEEE_DOUBLE_BIG_ENDIAN 1
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+#elif defined(__VFP_FP__)
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+# define IEEE_DOUBLE_MIXED_ENDIAN 0
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+# define IEEE_DOUBLE_BIG_ENDIAN 0
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+#else
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+# define IEEE_DOUBLE_BIG_ENDIAN 0
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+# define IEEE_DOUBLE_MIXED_ENDIAN 1
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+#endif
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diff -uNrp glibc.old/sysdeps/arm/ieee754.h glibc.new/sysdeps/arm/ieee754.h
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--- glibc.old/sysdeps/arm/ieee754.h 2001-07-07 15:21:19.000000000 -0400
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+++ glibc.new/sysdeps/arm/ieee754.h 1969-12-31 19:00:00.000000000 -0500
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@@ -1,115 +0,0 @@
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-/* Copyright (C) 1992, 1995, 1996, 1998 Free Software Foundation, Inc.
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- This file is part of the GNU C Library.
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-
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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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-
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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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-
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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, write to the Free
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- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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- 02111-1307 USA. */
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-
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-#ifndef _IEEE754_H
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-
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-#define _IEEE754_H 1
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-#include <features.h>
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-
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-#include <endian.h>
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-
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-__BEGIN_DECLS
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-
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-union ieee754_float
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- {
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- float f;
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-
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- /* This is the IEEE 754 single-precision format. */
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- struct
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- {
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- unsigned int mantissa:23;
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- unsigned int exponent:8;
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- unsigned int negative:1;
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- } ieee;
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-
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- /* This format makes it easier to see if a NaN is a signalling NaN. */
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- struct
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- {
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- unsigned int mantissa:22;
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- unsigned int quiet_nan:1;
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- unsigned int exponent:8;
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- unsigned int negative:1;
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- } ieee_nan;
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- };
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-
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-#define IEEE754_FLOAT_BIAS 0x7f /* Added to exponent. */
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-
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-
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-union ieee754_double
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- {
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- double d;
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-
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- /* This is the IEEE 754 double-precision format. */
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- struct
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- {
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- unsigned int mantissa0:20;
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- unsigned int exponent:11;
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- unsigned int negative:1;
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- unsigned int mantissa1:32;
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- } ieee;
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-
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- /* This format makes it easier to see if a NaN is a signalling NaN. */
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- struct
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- {
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- unsigned int mantissa0:19;
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- unsigned int quiet_nan:1;
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- unsigned int exponent:11;
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- unsigned int negative:1;
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- unsigned int mantissa1:32;
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- } ieee_nan;
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- };
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-
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-#define IEEE754_DOUBLE_BIAS 0x3ff /* Added to exponent. */
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-
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-
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-/* The following two structures are correct for `new' floating point systems but
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- wrong for the old FPPC. The only solution seems to be to avoid their use on
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- old hardware. */
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-
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-union ieee854_long_double
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- {
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- long double d;
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-
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- /* This is the IEEE 854 double-extended-precision format. */
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- struct
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- {
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- unsigned int exponent:15;
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- unsigned int empty:16;
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- unsigned int negative:1;
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- unsigned int mantissa1:32;
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- unsigned int mantissa0:32;
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- } ieee;
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-
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- /* This is for NaNs in the IEEE 854 double-extended-precision format. */
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- struct
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- {
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- unsigned int exponent:15;
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- unsigned int empty:16;
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- unsigned int negative:1;
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- unsigned int mantissa1:32;
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- unsigned int mantissa0:30;
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- unsigned int quiet_nan:1;
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- unsigned int one:1;
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- } ieee_nan;
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- };
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-
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-#define IEEE854_LONG_DOUBLE_BIAS 0x3fff
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-
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-__END_DECLS
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-
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-#endif /* ieee754.h */
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Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
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