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+/* __gmp_insert_double -- convert from array of mp_limb_t to double.
+
+Copyright (C) 1996, 1997, 1999, 2000 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP 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 MP 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 MP 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. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+#ifdef XDEBUG
+#undef _GMP_IEEE_FLOATS
+#endif
+
+#ifndef _GMP_IEEE_FLOATS
+#define _GMP_IEEE_FLOATS 0
+#endif
+
+double
+#if __STDC__
+__gmp_scale2 (double d, int exp)
+#else
+__gmp_scale2 (d, exp)
+ double d;
+ int exp;
+#endif
+{
+#if _GMP_IEEE_FLOATS
+ {
+#if defined (__alpha) && __GNUC__ == 2 && __GNUC_MINOR__ == 8
+ /* Work around alpha-specific bug in GCC 2.8.x. */
+ volatile
+#endif
+ union ieee_double_extract x;
+ x.d = d;
+ exp += x.s.exp;
+ x.s.exp = exp;
+ if (exp >= 2047)
+ {
+ /* Return +-infinity */
+ x.s.exp = 2047;
+ x.s.manl = x.s.manh = 0;
+ }
+ else if (exp < 1)
+ {
+ x.s.exp = 1; /* smallest exponent (biased) */
+ /* Divide result by 2 until we have scaled it to the right IEEE
+ denormalized number, but stop if it becomes zero. */
+ while (exp < 1 && x.d != 0)
+ {
+ x.d *= 0.5;
+ exp++;
+ }
+ }
+ return x.d;
+ }
+#else
+ {
+ double factor, r;
+
+ factor = 2.0;
+ if (exp < 0)
+ {
+ factor = 0.5;
+ exp = -exp;
+ }
+ r = d;
+ if (exp != 0)
+ {
+ if ((exp & 1) != 0)
+ r *= factor;
+ exp >>= 1;
+ while (exp != 0)
+ {
+ factor *= factor;
+ if ((exp & 1) != 0)
+ r *= factor;
+ exp >>= 1;
+ }
+ }
+ return r;
+ }
+#endif
+}