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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/generic/frexp.c
initial import
Diffstat (limited to 'sysdeps/generic/frexp.c')
-rw-r--r--sysdeps/generic/frexp.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/sysdeps/generic/frexp.c b/sysdeps/generic/frexp.c
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+++ b/sysdeps/generic/frexp.c
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+/* Copyright (C) 1991, 1992 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 Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <ansidecl.h>
+#include <errno.h>
+#include <math.h>
+
+/* Break VALUE into a normalized fraction and an integral power of 2. */
+double
+DEFUN(frexp, (value, exp), double value AND int *exp)
+{
+#ifdef NAN
+ if (__isinf (value))
+ {
+ errno = EDOM;
+ *exp = 0;
+ return __copysign (NAN, value);
+ }
+#endif
+
+ if (__isnan (value))
+ {
+ errno = EDOM;
+ *exp = 0;
+ return value;
+ }
+
+ if (value == 0)
+ {
+ *exp = 0;
+ return value;
+ }
+
+ /* Add one to the exponent of the number,
+ so we have one digit before the binary point. */
+ *exp = (int) __logb (value) + 1;
+ return ldexp (value, - *exp);
+}