Taken from http://sources.redhat.com/ml/crossgcc/2004-02/msg00104.html
Author: addsub@eyou.com
Target: ARM

Fixes http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/920501-8.c
and makes printf("%f", 1.0) work.

Lennert Buytenhek wrote in http://sources.redhat.com/ml/crossgcc/2004-09/msg00115.html :
 It ... fixes the 'printf("%f\n", 0.5); prints 0.000000' and general 'floating point
 is broken' on my big-endian hardfloat FPA ARM platform. ...
 It's definitely needed for hardfloat.  So I'd think it's needed for
 big-endian systems in any case, and for VFP on little-endian systems
 too.  Someone would have to verify that though.

Lennert Buytenhek wrote in http://sources.redhat.com/ml/crossgcc/2004-09/msg00123.html
 I just had a look at glibc-20040830, and [this patch] is still needed and useful
 for this version.  glibc-20040830 out-of-the-box still contains the
 following wrong assumptions:
 - sysdeps/arm/bits/endian.h: float word order is big endian (which it is
   not on vfp systems)
 - sysdeps/arm/gmp-mparam.h: IEEE doubles are mixed endian (which they
   are not on big endian systems, neither on vfp systems)
 - sysdeps/arm/ieee754.h: IEEE doubles are in little endian byte order
   (which they are not on big endian systems)
 [This patch] seems the right solution for all of these issues.

Dimitry Andric wrote in http://sources.redhat.com/ml/crossgcc/2004-09/msg00132.html :
 It's even needed for glibc CVS, AFAICS.
 The patch hunk which modifies glibc.new/sysdeps/arm/bits/endian.h
 (currently at version 1.4) is only needed for proper VFP operation.
 But the hunk which modifies sysdeps/arm/gmp-mparam.h, and the hunk
 that deletes sysdeps/arm/ieee754.h (yes, this IS correct), are needed
 for proper operation of *any* FP model on big endian ARM.

See also discussion in followups to
http://sources.redhat.com/ml/crossgcc/2004-05/msg00245.html)

Message-ID: <276985760.37584@eyou.com>
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Date: 17 Feb 2004 10:42:38 +0800
Message-ID: <20040217104238.8237.qmail@eyou.com>
From: "add" <addsub@eyou.com>
To: dank@kegel.com
Reply-To: "add" <addsub@eyou.com>
Subject: Re:&nbsp;&nbsp;&nbsp;problem&nbsp;while&nbsp;building&nbsp;arm&nbsp;vfp&nbsp;softfloat&nbsp;gcc&nbsp;`

Hi, Dan, This is a patch I applied to my glibc-2.3.2, then my softfloat
toolchain can printf("%f\n",1.0). So you may have a try of this


diff -uNrp glibc.old/sysdeps/arm/bits/endian.h glibc.new/sysdeps/arm/bits/endian.h
--- glibc.old/sysdeps/arm/bits/endian.h	1999-04-12 11:59:13.000000000 -0400
+++ glibc.new/sysdeps/arm/bits/endian.h	2004-02-12 09:15:13.000000000 -0500
@@ -9,4 +9,9 @@
 #else
 #define __BYTE_ORDER __LITTLE_ENDIAN
 #endif
+
+#ifdef __VFP_FP__
+#define __FLOAT_WORD_ORDER __BYTE_ORDER
+#else
 #define __FLOAT_WORD_ORDER __BIG_ENDIAN
+#endif
diff -uNrp glibc.old/sysdeps/arm/gmp-mparam.h glibc.new/sysdeps/arm/gmp-mparam.h
--- glibc.old/sysdeps/arm/gmp-mparam.h	2001-07-07 15:21:19.000000000 -0400
+++ glibc.new/sysdeps/arm/gmp-mparam.h	2004-02-12 09:15:13.000000000 -0500
@@ -26,5 +26,13 @@ MA 02111-1307, USA. */
 #define BITS_PER_SHORTINT 16
 #define BITS_PER_CHAR 8
 
-#define IEEE_DOUBLE_BIG_ENDIAN 0
-#define IEEE_DOUBLE_MIXED_ENDIAN 1
+#if defined(__ARMEB__)
+# define IEEE_DOUBLE_MIXED_ENDIAN 0
+# define IEEE_DOUBLE_BIG_ENDIAN 1
+#elif defined(__VFP_FP__)
+# define IEEE_DOUBLE_MIXED_ENDIAN 0
+# define IEEE_DOUBLE_BIG_ENDIAN 0
+#else
+# define IEEE_DOUBLE_BIG_ENDIAN 0
+# define IEEE_DOUBLE_MIXED_ENDIAN 1
+#endif
diff -uNrp glibc.old/sysdeps/arm/ieee754.h glibc.new/sysdeps/arm/ieee754.h
--- glibc.old/sysdeps/arm/ieee754.h	2001-07-07 15:21:19.000000000 -0400
+++ glibc.new/sysdeps/arm/ieee754.h	1969-12-31 19:00:00.000000000 -0500
@@ -1,115 +0,0 @@
-/* Copyright (C) 1992, 1995, 1996, 1998 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, write to the Free
-   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
-   02111-1307 USA.  */
-
-#ifndef _IEEE754_H
-
-#define _IEEE754_H 1
-#include <features.h>
-
-#include <endian.h>
-
-__BEGIN_DECLS
-
-union ieee754_float
-  {
-    float f;
-
-    /* This is the IEEE 754 single-precision format.  */
-    struct
-      {
-	unsigned int mantissa:23;
-	unsigned int exponent:8;
-	unsigned int negative:1;
-      } ieee;
-
-    /* This format makes it easier to see if a NaN is a signalling NaN.  */
-    struct
-      {
-	unsigned int mantissa:22;
-	unsigned int quiet_nan:1;
-	unsigned int exponent:8;
-	unsigned int negative:1;
-      } ieee_nan;
-  };
-
-#define IEEE754_FLOAT_BIAS	0x7f /* Added to exponent.  */
-
-
-union ieee754_double
-  {
-    double d;
-
-    /* This is the IEEE 754 double-precision format.  */
-    struct
-      {
-	unsigned int mantissa0:20;
-	unsigned int exponent:11;
-	unsigned int negative:1;
-	unsigned int mantissa1:32;
-      } ieee;
-
-    /* This format makes it easier to see if a NaN is a signalling NaN.  */
-    struct
-      {
-	unsigned int mantissa0:19;
-	unsigned int quiet_nan:1;
-	unsigned int exponent:11;
-	unsigned int negative:1;
-	unsigned int mantissa1:32;
-      } ieee_nan;
-  };
-
-#define IEEE754_DOUBLE_BIAS	0x3ff /* Added to exponent.  */
-
-
-/* The following two structures are correct for `new' floating point systems but
-   wrong for the old FPPC.  The only solution seems to be to avoid their use on
-   old hardware.  */
-
-union ieee854_long_double
-  {
-    long double d;
-
-    /* This is the IEEE 854 double-extended-precision format.  */
-    struct
-      {
-	unsigned int exponent:15;
-	unsigned int empty:16;
-	unsigned int negative:1;
-	unsigned int mantissa1:32;
-	unsigned int mantissa0:32;
-      } ieee;
-
-    /* This is for NaNs in the IEEE 854 double-extended-precision format.  */
-    struct
-      {
-	unsigned int exponent:15;
-	unsigned int empty:16;
-	unsigned int negative:1;
-	unsigned int mantissa1:32;
-	unsigned int mantissa0:30;
-	unsigned int quiet_nan:1;
-	unsigned int one:1;
-      } ieee_nan;
-  };
-
-#define IEEE854_LONG_DOUBLE_BIAS 0x3fff
-
-__END_DECLS
-
-#endif /* ieee754.h */

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
