1 files changed, 46 insertions, 0 deletions
diff --git a/src/powerof2.c b/src/powerof2.c
new file mode 100644
index 000000000..4283ee455
--- /dev/null
+++ b/src/powerof2.c
@@ -0,0 +1,46 @@
+/* mpfr_powerof2_raw -- test whether a floating-point number is a power of 2
+
+Copyright 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+Contributed by the Arenaire and Caramel projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU 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 3 of the License, or (at your
+option) any later version.
+
+The GNU 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 GNU MPFR Library; see the file COPYING.LESSER.  If not, see
+http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+#include "mpfr-impl.h"
+
+/* This is an internal function and one assumes that x is a real number. */
+
+int
+mpfr_powerof2_raw (mpfr_srcptr x)
+{
+  mp_limb_t *xp;
+  mp_size_t xn;
+
+  /* This is an internal function, and we may call it with some
+     wrong numbers (ie good mantissa but wrong flags or exp)
+     So we don't want to test if it is a pure FP.
+     MPFR_ASSERTN(MPFR_IS_PURE_FP(x)); */
+  xp = MPFR_MANT(x);
+  xn = (MPFR_PREC(x) - 1) / GMP_NUMB_BITS;
+  /*if (NOT_POW2(xp[xn]))*/
+  if (xp[xn] != MPFR_LIMB_HIGHBIT)
+    return 0;
+  while (xn > 0)
+    if (xp[--xn] != 0)
+      return 0;
+  return 1;
+}