Add MPFR_INT_CEIL_LOG2 macro and __gmpfr_int_ceil_log2 function

(don't use function but macro).


git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@2952 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 35 insertions, 0 deletions

diff --git a/int_ceil_log2.c b/int_ceil_log2.c
new file mode 100644
index 000000000..2e7b63d8e
--- /dev/null
+++ b/int_ceil_log2.c
@@ -0,0 +1,35 @@
+/* __gmpfr_int_ceil_log2 -- Integer ceil of log2(x)
+
+Copyright 2004 Free Software Foundation, Inc.
+
+This file is part of the MPFR Library.
+
+The MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#define MPFR_NEED_LONGLONG_H /* for count_leading_zeros */
+#include "mpfr-impl.h"
+
+int
+__gmpfr_int_ceil_log2 (unsigned long n)
+{
+  int b;
+  mp_limb_t limb = n;
+
+  MPFR_ASSERTD (limb == n);
+
+  count_leading_zeros (b, limb);
+  return BITS_PER_MP_LIMB-b;
+}