@@ -1,22 +1,24 @@
-/* @(#)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.
- * ====================================================
- */
+/* Compute radix independent exponent.
+ Copyright (C) 2011-2019 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
-/*
- * double logb(x)
- * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
- * Use ilogb instead.
- */
+ 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, see
+ <http://www.gnu.org/licenses/>. */
#include <math.h>
+
#include <math_private.h>
#include <libm-alias-double.h>
#include <fix-int-fp-convert-zero.h>
@@ -24,28 +26,23 @@
double
__logb (double x)
{
- int32_t lx, ix, rix;
+ int64_t ix, ex;
- EXTRACT_WORDS (ix, lx, x);
- ix &= 0x7fffffff; /* high |x| */
- if ((ix | lx) == 0)
+ EXTRACT_WORDS64 (ix, x);
+ ix &= UINT64_C(0x7fffffffffffffff);
+ if (ix == 0)
return -1.0 / fabs (x);
- if (ix >= 0x7ff00000)
+ ex = ix >> 52;
+ if (ex == 0x7ff)
return x * x;
- if (__glibc_unlikely ((rix = ix >> 20) == 0))
+ if (__glibc_unlikely (ex == 0))
{
- /* POSIX specifies that denormal number is treated as
- though it were normalized. */
- int ma;
- if (ix == 0)
- ma = __builtin_clz (lx) + 32;
- else
- ma = __builtin_clz (ix);
- rix -= ma - 12;
+ int m = __builtin_clzll (ix);
+ ex -= m - 12;
}
- if (FIX_INT_FP_CONVERT_ZERO && rix == 1023)
+ if (FIX_INT_FP_CONVERT_ZERO && ex == 1023)
return 0.0;
- return (double) (rix - 1023);
+ return (double) (ex - 1023);
}
#ifndef __logb
libm_alias_double (__logb, logb)
deleted file mode 100644
@@ -1,47 +0,0 @@
-/* Compute radix independent exponent.
- Copyright (C) 2011-2019 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
-
- 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, see
- <http://www.gnu.org/licenses/>. */
-
-#include <math.h>
-
-#include <math_private.h>
-#include <libm-alias-double.h>
-
-
-double
-__logb (double x)
-{
- int64_t ix, ex;
-
- EXTRACT_WORDS64 (ix, x);
- ix &= UINT64_C(0x7fffffffffffffff);
- if (ix == 0)
- return -1.0 / fabs (x);
- ex = ix >> 52;
- if (ex == 0x7ff)
- return x * x;
- if (__glibc_unlikely (ex == 0))
- {
- int m = __builtin_clzll (ix);
- ex -= m - 12;
- }
- return (double) (ex - 1023);
-}
-#ifndef __logb
-libm_alias_double (__logb, logb)
-#endif
- The resulting binary difference on 32 bits architecture is minimum. On i686-linux-gnu (with architecture optimization routine removed) there is no different using logb benchtests - It helps wordsize-64 architectures that use ldbl-opt. - It add some code simplification with reduction of duplicated implementations. Checked on powerpc-linux-gnu (built without --with-cpu, with --with-cpu=power4 and with --with-cpu=power5+ and --disable-multi-arch), powerpc64-linux-gnu (built without --with-cp and with --with-cpu=power5+ and --disable-multi-arch). * sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c: Move to ... * sysdeps/ieee754/dbl-64/s_logb.c: ... here. Add work around for powerpc32 integer 0 converting to -0. --- sysdeps/ieee754/dbl-64/s_logb.c | 61 ++++++++++----------- sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c | 47 ---------------- 2 files changed, 29 insertions(+), 79 deletions(-) delete mode 100644 sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c -- 2.17.1