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Re: [Bug math/887] Math library function "nextafter()" isinconsistent on PowerPC
- From: Uttam Pawar <uttamp at us dot ibm dot com>
- To: libc-alpha at sources dot redhat dot com
- Date: Thu, 14 Jul 2005 16:23:57 -0700
- Subject: 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