[src/trunk]: src/lib/libm/noieee_src log2() for vax

[martin <martin%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/fcaa5f34ea86
branches:  trunk
changeset: 327376:fcaa5f34ea86
user:      martin <martin%NetBSD.org@localhost>
date:      Thu Mar 06 10:57:01 2014 +0000

description:
log2() for vax

diffstat:

 lib/libm/noieee_src/n_log2.c |  59 ++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 59 insertions(+), 0 deletions(-)

diffs (63 lines):

diff -r 0667ddff384c -r fcaa5f34ea86 lib/libm/noieee_src/n_log2.c
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/libm/noieee_src/n_log2.c      Thu Mar 06 10:57:01 2014 +0000
@@ -0,0 +1,59 @@
+/*      $NetBSD: n_log2.c,v 1.1 2014/03/06 10:57:01 martin Exp $ */
+/*-
+ * Copyright (c) 2014 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Martin Husemann <martin%NetBSD.org@localhost>.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* LOG2(X)
+ * RETURN THE BASE 10 LOGARITHM OF x
+ *
+ * Required kernel function:
+ *     log(x)
+ *
+ * Method :
+ *                         log(x)
+ *             log2(x) =  ---------
+ *                         log(2)
+ */
+
+#define _LIBM_STATIC
+#include "mathimpl.h"
+
+
+static const double ln2 = .6931471805599453094172321214581765680755;
+
+double
+log2(double x)
+{
+       return log(x)/ln2;
+}
+
+float
+log2f(float x)
+{
+       return logf(x)/ln2;
+}