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Re: [Bug math/887] Math library function "logb" is inconsistent
- From: Uttam Pawar <uttamp at us dot ibm dot com>
- To: libc-alpha at sources dot redhat dot com
- Date: Thu, 14 Jul 2005 10:47:56 -0700
- Subject: Re: [Bug math/887] Math library function "logb" is inconsistent
- References: <20050428174956.887.uttamp@us.ibm.com> <20050429203831.2725.qmail@sourceware.org>
On Fri, 2005-04-29 at 20:38 +0000, uttamp at us dot ibm dot com wrote:
> ------- Additional Comments From uttamp at us dot ibm dot com 2005-04-29 20:38 -------
> Created an attachment (id=470)
> --> (http://sources.redhat.com/bugzilla/attachment.cgi?id=470&action=view)
> A propsed patch to fix bug in logb() function on powerpc arch.
>
>
Proposed patch for logb() function on PowerPC.
-----------------------------------------------------------------------
diff -urN glibc-20041219T2331/ChangeLog
glibc-20041219T2331.mine/ChangeLog
--- glibc-20041219T2331/ChangeLog 2005-06-16 15:37:04.236481392 -0700
+++ glibc-20041219T2331.mine/ChangeLog 2005-06-16 15:36:52.128457832
-0700
@@ -1,3 +1,8 @@
+2005-06-10 Steven Munroe <sjmunroe@us.ibm.com>
+
+ * sysdeps/powerpc/powerpc32/fpu/s_logb.c: New file.
+ * sysdeps/powerpc/powerpc32/fpu/s_logbf.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/powerpc32/fpu/s_logb.c
glibc-20041219T2331.mine/sysdeps/powerpc/powerpc32/fpu/s_logb.c
--- glibc-20041219T2331/sysdeps/powerpc/powerpc32/fpu/s_logb.c
2005-06-15 18:14:09.444408520 -0700
+++ glibc-20041219T2331.mine/sysdeps/powerpc/powerpc32/fpu/s_logb.c
2005-06-16 16:13:54.149435728 -0700
@@ -0,0 +1,75 @@
+/* @(#)s_logb.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_logb.c,v 1.8 1995/05/10 20:47:50 jtc
Exp $";
+#endif
+
+/*
+ * double logb(x)
+ * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
+ * Use ilogb instead.
+ */
+
+#include "math.h"
+#include "math_private.h"
+#include <fenv.h>
+
+#ifdef __STDC__
+ double __logb(double x)
+#else
+ double __logb(x)
+ double x;
+#endif
+{
+ int32_t lx,ix;
+ EXTRACT_WORDS(ix,lx,x);
+ ix &= 0x7fffffff; /* high |x| */
+ if((ix|lx)==0) return -1.0/fabs(x);
+ if(ix>=0x7ff00000) return x*x;
+ if((ix>>=20)==0) /* IEEE 754 logb */
+ return -1022.0;
+ else
+ {
+ double result;
+ int round_mode = fegetround();
+ fesetround(FE_TONEAREST);
+ result = (double) (ix-1023);
+ fesetround(round_mode);
+ return result;
+ }
+}
+weak_alias (__logb, logb)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__logb, __logbl)
+weak_alias (__logb, logbl)
+#endif
+
diff -urN glibc-20041219T2331/sysdeps/powerpc/powerpc32/fpu/s_logbf.c
glibc-20041219T2331.mine/sysdeps/powerpc/powerpc32/fpu/s_logbf.c
--- glibc-20041219T2331/sysdeps/powerpc/powerpc32/fpu/s_logbf.c
1969-12-31 16:00:00.000000000 -0800
+++ glibc-20041219T2331.mine/sysdeps/powerpc/powerpc32/fpu/s_logbf.c
2005-06-16 16:27:20.550450016 -0700
@@ -0,0 +1,67 @@
+/* s_logbf.c -- float version of s_logb.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support,
ian@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * 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_logbf.c,v 1.4 1995/05/10 20:47:51 jtc
Exp $";+#endif
+#endif
+#include "math.h"
+#include "math_private.h"
+#include <fenv.h>
+
+#ifdef __STDC__
+ float __logbf(float x)
+#else
+ float __logbf(x)
+ float x;
+#endif
+{
+ int32_t ix;
+ GET_FLOAT_WORD(ix,x);
+ ix &= 0x7fffffff; /* high |x| */
+ if(ix==0) return (float)-1.0/fabsf(x);
+ if(ix>=0x7f800000) return x*x;
+ if((ix>>=23)==0) /* IEEE 754 logb */
+ return -126.0;
+ else
+ {
+ float result;
+ int round_mode = fegetround();
+ fesetround(FE_TONEAREST);
+ result = (float) (ix-127);
+ fesetround(round_mode);
+ return result;
+ }
+}
+weak_alias (__logbf, logbf)
+
Regards,
Uttam