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Re: [Bug math/887] Math library function "nextafter()" isinconsistent on PowerPC


Hi,

This is a proposed patch for nextafter() to fix the inconsistent result.
This has been verified only on PowerPC platform.

This patch has also attached with this email.

Regards,

Uttam

---------------------------------

diff -urN glibc-20041219T2331/ChangeLog
glibc-20041219T2331.mine/ChangeLog
--- glibc-20041219T2331/ChangeLog	2005-07-14 17:01:20.554039464 -0700
+++ glibc-20041219T2331.mine/ChangeLog	2005-07-14 23:14:00.708088632
-0700
@@ -1,3 +1,7 @@
+2005-07-10  Uttam Pawar  <uttamp@us.ibm.com>
+
+	* sysdeps/powerpc/fpu/s_nextafter.c: New file.
+
 2004-12-19  Roland McGrath  <roland@redhat.com>
 
 	* iconv/iconvconfig.c (nostdlib, output_file, output_file_len):
diff -urN glibc-20041219T2331/sysdeps/powerpc/fpu/s_nextafter.c
glibc-20041219T2331.mine/sysdeps/powerpc/fpu/s_nextafter.c
--- glibc-20041219T2331/sysdeps/powerpc/fpu/s_nextafter.c	1969-12-31
16:00:00.000000000 -0800
+++ glibc-20041219T2331.mine/sysdeps/powerpc/fpu/s_nextafter.c
2005-07-14 16:58:18.869098592 -0700
@@ -0,0 +1,131 @@
+/* @(#)s_nextafter.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+/*
+   Copyright (C) 2005 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.  */
+
+#if defined(LIBM_SCCS) && !defined(lint)
+static char rcsid[] = "$NetBSD: s_nextafter.c,v 1.8 1995/05/10 20:47:58
jtc Exp $";
+#endif
+
+/* IEEE functions
+ *	nextafter(x,y)
+ *	return the next machine floating-point number of x in the
+ *	direction toward y.
+ *   Special cases:
+ */
+
+/* Ugly hack so that the aliasing works.  */
+#define __nexttoward __internal___nexttoward
+#define nexttoward __internal_nexttoward
+
+#include "math.h"
+#include "math_private.h"
+#include <float.h>
+#include <fenv.h>
+
+#ifdef __STDC__
+	double __nextafter(double x, double y)
+#else
+	double __nextafter(x,y)
+	double x,y;
+#endif
+{
+	int32_t hx,hy,ix,iy;
+	u_int32_t lx,ly;
+
+	EXTRACT_WORDS(hx,lx,x);
+	EXTRACT_WORDS(hy,ly,y);
+	ix = hx&0x7fffffff;		/* |x| */
+	iy = hy&0x7fffffff;		/* |y| */
+
+	if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||   /* x is nan */
+	   ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)){    /* y is nan */
+           return x+y;
+        } else if(x==y) { 
+           return y;		/* x=y, return y */
+	} else if((ix|lx)==0) {			/* x == 0 */
+	    INSERT_WORDS(x,hy&0x80000000,1);	/* return +-minsubnormal */
+	    y = x*x;
+	    if(y==x) 
+                return y; 
+            else 
+                return x;	/* raise underflow flag */
+	} else 
+	if(hx>=0) {				/* x > 0 */
+	    if(hx>hy||((hx==hy)&&(lx>ly))) {	/* x > y, x -= ulp */
+		if(lx==0) hx -= 1;
+		lx -= 1;
+	    } else {				/* x < y, x += ulp */
+		lx += 1;
+		if(lx==0) hx += 1;
+	    }
+	} else {				/* x < 0 */
+	    if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
+		if(lx==0) hx -= 1;
+		lx -= 1;
+	    } else {				/* x > y, x += ulp */
+		lx += 1;
+		if(lx==0) hx += 1;
+	    }
+	}
+        
+        hy = hx&0x7ff00000;
+        if(hy>=0x7ff00000) {
+          int round_mode=fegetround();
+          fesetround(FE_TONEAREST);
+          asm ("" : : : "memory"); /* workaround to compiler (gcc)
optimization 
+                                   till #pragma is implemented */
+	  x = x+x;	/* overflow  */
+	  if (FLT_EVAL_METHOD != 0 && FLT_EVAL_METHOD != 1)
+	    asm ("" : "=m"(x) : "m"(x));
+	  asm ("" : : : "memory"); /* workaround to compiler (gcc)
optimization 
+                                   till #pragma is implemented */
+	  fesetround(round_mode);
+	  return x;	/* overflow  */
+	}
+	if(hy<0x00100000) {		/* underflow */
+	    y = x*x;
+	    if(y!=x) {		/* raise underflow flag */
+	        INSERT_WORDS(y,hx,lx);
+		return y;
+	    }
+	}
+	INSERT_WORDS(x,hx,lx);
+	return x;
+}
+weak_alias (__nextafter, nextafter)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__nextafter, __nextafterl)
+weak_alias (__nextafter, nextafterl)
+strong_alias (__nextafter, __nexttowardl)
+weak_alias (__nexttowardl, nexttowardl)
+#undef __nexttoward
+strong_alias (__nextafter, __nexttoward)
+#undef nexttoward
+weak_alias (__nextafter, nexttoward)
+#endif



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